Dr. Jacinda Sampson received her MD and a PhD in biochemistry from University of Alabama at Birmingham, and completed her neurology residency and neurogenetics fellowship at the University of Utah. She served at Columbia University Medical Center prior to joining Stanford University Medical Center in 2015. Her areas of interest include myotonic dystrophies, Duchenne muscular dystrophy, and neurogenetic disorders such as neurofibromatosis, hereditary spastic paraparesis, spinocerebellar ataxia, among others. She is interested in clinical trials for treatment of neurogenetic disorders, and is the clinical application of next-generation genomic sequencing to genetic testing.
Honors & Awards
Stephen Q. Shafer Award for Humanism in Neurology, Columbia University Neurology Residents (2014)
Fellowship: University of Utah School of Medicine Registrar (2006) UT
Board Certification: American Board of Psychiatry and Neurology, Neurology (2005)
Residency: University of Utah School of Medicine (2004) UT
Internship: University of Utah School of Medicine (2001) UT
Medical Education: University of Alabama at Birmingham (2000) AL
Fellowship, University of Utah School of Medicine, Neurogenetics (2006)
Residency, University of Utah School of Medicine, Neurology (2004)
Internship, University of Utah School of Medicine, Internal Medicine (2001)
PhD, University of Alabama, Biochemistry (1999)
MD, University of Alabama School of Medicine, Medical Degree (2000)
Safety, Tolerability and Pharmacokinetics of ERX-963 in Adults With Myotonic Dystrophy Type 1
Participants in this study will receive two treatments, placebo and ERX-963, on different days in a randomized fashion. The primary purpose of this study is to investigate the safety and tolerability of ERX-963 in participants diagnosed with Myotonic Dystrophy, Type 1 (DM1). The secondary purpose is to evaluate the potential of ERX-963 treatment to reduce excessive daytime sleepiness / hypersomnia and improve cognitive function in DM1 participants compared to placebo treatment.
Stanford is currently not accepting patients for this trial. For more information, please contact Mitchell Reddan, 650-725-4341.
The Effect of Exercise on Muscle Dysfunction in Cystinosis
Classification of activity tolerance is of importance in chronic progressive myopathies, not only to better understand functional implications of the disease state itself, but also for purposes of exercise prescription for health maintenance. Maximal exercise testing has been considered as the gold standard of assessing maximal aerobic capacity, however testing in individuals with neuromuscular disease is often limited due to pain, activity intolerance, musculoskeletal impairments, fatigue and other such related variables. Often, submaximal exercise testing can overcome some of these obstacles, and as such, is used frequently in the clinical environment. Non-ambulatory exercise testing utilizing an arm ergometer specifically has not been studied as heavily, especially in those with progressive myopathies. For this study, we will use maximal aerobic capacity testing for individuals with Cystinosis Myopathy utilizing a bike ergometer to allow testing of individuals regardless of their ambulatory status.
Stanford is currently not accepting patients for this trial. For more information, please contact Tina Duong, MPT, PHDc, 703-855-9677.
Genetic counselor roles in the undiagnosed diseases network research study: Clinical care, collaboration, and curation.
Journal of genetic counseling
Genetic counselors (GCs) are increasingly filling important positions on research study teams, but there is limited literature describing the roles of GCs in these settings. GCs on the Undiagnosed Diseases Network (UDN) study team serve in a variety of roles across the research network and provide an opportunity to better understand genetic counselor roles in research. To quantitatively characterize the tasks regularly performed and professional fulfillment derived from these tasks, two surveys were administered to UDN GCs in a stepwise fashion. Responses from the first, free-response survey elicited the scope of tasks which informed development of a second structured, multiple-select survey. In survey 2, respondents were asked to select which roles they performed. Across 19 respondents, roles in survey 2 received a total of 947 selections averaging approximately 10 selections per role. When asked to indicate what roles they performed, respondent selected a mean of 50 roles (range 22-70). Survey 2 data were analyzed via thematic coding of responses and hierarchical cluster analysis to identify patterns in responses. From the thematic analysis, 20 non-overlapping codes emerged in seven categories: clinical interaction and care, communication, curation, leadership, participant management, research, and team management. Three themes emerged from the categories that represented the roles of GCs in the UDN: clinical care, collaboration, and curation. Cluster analyses showed that responses were more similar among individuals at the same institution than between institutions. This study highlights the ways GCs apply their unique skill set in the context of a clinical translational research network. Additionally, findings from this study reinforce the wide applicability of core skills that are part of genetic counseling training. Clinical literacy, genomics expertise and analysis, interpersonal, psychosocial and counseling skills, education, professional practice skills, and an understanding of research processes make genetic counselors well suited for such roles and poised to positively impact research experiences and outcomes for participants.
View details for DOI 10.1002/jgc4.1493
View details for PubMedID 34374469
Characterization of HNRNPA1 mutations defines diversity in pathogenic mechanisms and clinical presentation.
2021; 6 (14)
Mutations in HNRNPA1 encoding heterogeneous nuclear ribonucleoprotein (hnRNP) A1 are a rare cause of amyotrophic lateral sclerosis (ALS) and multisystem proteinopathy (MSP). hnRNPA1 is part of the group of RNA-binding proteins (RBPs) that assemble with RNA to form RNPs. hnRNPs are concentrated in the nucleus and function in pre-mRNA splicing, mRNA stability, and the regulation of transcription and translation. During stress, hnRNPs, mRNA, and other RBPs condense in the cytoplasm to form stress granules (SGs). SGs are implicated in the pathogenesis of (neuro-)degenerative diseases, including ALS and inclusion body myopathy (IBM). Mutations in RBPs that affect SG biology, including FUS, TDP-43, hnRNPA1, hnRNPA2B1, and TIA1, underlie ALS, IBM, and other neurodegenerative diseases. Here, we characterize 4 potentially novel HNRNPA1 mutations (yielding 3 protein variants: *321Eext*6, *321Qext*6, and G304Nfs*3) and 2 known HNRNPA1 mutations (P288A and D262V), previously connected to ALS and MSP, in a broad spectrum of patients with hereditary motor neuropathy, ALS, and myopathy. We establish that the mutations can have different effects on hnRNPA1 fibrillization, liquid-liquid phase separation, and SG dynamics. P288A accelerated fibrillization and decelerated SG disassembly, whereas *321Eext*6 had no effect on fibrillization but decelerated SG disassembly. By contrast, G304Nfs*3 decelerated fibrillization and impaired liquid phase separation. Our findings suggest different underlying pathomechanisms for HNRNPA1 mutations with a possible link to clinical phenotypes.
View details for DOI 10.1172/jci.insight.148363
View details for PubMedID 34291734
A variant of uncertain significance in SDHAF1, the succinate dehydrogenase chaperone protein, in an adult patient with spastic paraparesis and leukoencephalopathy.
Multiple sclerosis and related disorders
2021; 54: 103132
Succinate dehydrogenase (SDH), or respiratory complex II, consists of four nuclear-encoded subunits. The chaperone protein succinate dehydrogenase assembly factor 1 (SDHAF1) plays an essential role in the assembly of SDH, and in the incorporation of iron-sulfur clusters into the SDHB subunit. SDHB couples the oxidation of succinate to fumarate with the reduction of ubiquinone (coenzyme Q) to ubiquinol. Previously reported mutations in SDHAF1 have been associated with infantile leukoencephalopathy. We report an adult case with a homozygous variant of uncertain significance (VUS) mutation in SDHAF1, presenting with dementia, spastic paraparesis, and cardiomyopathy, initially diagnosed as multiple sclerosis.
View details for DOI 10.1016/j.msard.2021.103132
View details for PubMedID 34289436
- Advances in the therapy of Spinal Muscular Atrophy. The Journal of pediatrics 2021
Dominant and Recessive Congenital Myasthenic Syndromes Caused by SYT2 Mutations.
Muscle & nerve
INTRODUCTION: We studied a patient with a congenital myasthenic syndrome (CMS) caused by a dominant mutation in the synaptotagmin 2 gene (SYT2) and compared the clinical features of this patient with those of a previously described patient with a recessive mutation in the same gene.METHODS: We performed electrodiagnostic (EDX) studies, genetic studies, muscle biopsy, microelectrode recordings and electron microscopy (EM).RESULTS: Both patients presented with muscle weakness and bulbar deficits, which were worse in the recessive form. EDX studies showed presynaptic failure, which was more prominent in the recessive form. Microelectrode studies in the dominant form showed a marked reduction of the quantal content, which increased linearly with higher frequencies of nerve stimulation. The MEPP frequencies were normal at rest but increased markedly with higher frequencies of nerve stimulation. The EM demonstrated overdeveloped postsynaptic folding, and abundant endosomes, multivesicular bodies and degenerative lamellar bodies inside small nerve terminals.DISCUSSION: The recessive form of CMS caused by a SYT2 mutation showed far more severe clinical manifestations than the dominant form. The pathogenesis of the dominant form likely involves a dominant-negative effect due to disruption of the dual function of synaptotagmin as a Ca2+ -sensor and modulator of synaptic vesicle exocytosis. This article is protected by copyright. All rights reserved.
View details for DOI 10.1002/mus.27332
View details for PubMedID 34037996
A resource of lipidomics and metabolomics data from individuals with undiagnosed diseases
2021; 8 (1): 114
Every year individuals experience symptoms that remain undiagnosed by healthcare providers. In the United States, these rare diseases are defined as a condition that affects fewer than 200,000 individuals. However, there are an estimated 7000 rare diseases, and there are an estimated 25-30 million Americans in total (7.6-9.2% of the population as of 2018) affected by such disorders. The NIH Common Fund Undiagnosed Diseases Network (UDN) seeks to provide diagnoses for individuals with undiagnosed disease. Mass spectrometry-based metabolomics and lipidomics analyses could advance the collective understanding of individual symptoms and advance diagnoses for individuals with heretofore undiagnosed disease. Here, we report the mass spectrometry-based metabolomics and lipidomics analyses of blood plasma, urine, and cerebrospinal fluid from 148 patients within the UDN and their families, as well as from a reference population of over 100 individuals with no known metabolic diseases. The raw and processed data are available to the research community so that they might be useful in the diagnoses of current or future patients suffering from undiagnosed disorders.
View details for DOI 10.1038/s41597-021-00894-y
View details for Web of Science ID 000642148100001
View details for PubMedID 33883556
View details for PubMedCentralID PMC8060404
Variants in PRKAR1B cause a neurodevelopmental disorder with autism spectrum disorder, apraxia, and insensitivity to pain
GENETICS IN MEDICINE
We characterize the clinical and molecular phenotypes of six unrelated individuals with intellectual disability and autism spectrum disorder who carry heterozygous missense variants of the PRKAR1B gene, which encodes the R1β subunit of the cyclic AMP-dependent protein kinase A (PKA).Variants of PRKAR1B were identified by single- or trio-exome analysis. We contacted the families and physicians of the six individuals to collect phenotypic information, performed in vitro analyses of the identified PRKAR1B-variants, and investigated PRKAR1B expression during embryonic development.Recent studies of large patient cohorts with neurodevelopmental disorders found significant enrichment of de novo missense variants in PRKAR1B. In our cohort, de novo origin of the PRKAR1B variants could be confirmed in five of six individuals, and four carried the same heterozygous de novo variant c.1003C>T (p.Arg335Trp; NM_001164760). Global developmental delay, autism spectrum disorder, and apraxia/dyspraxia have been reported in all six, and reduced pain sensitivity was found in three individuals carrying the c.1003C>T variant. PRKAR1B expression in the brain was demonstrated during human embryonal development. Additionally, in vitro analyses revealed altered basal PKA activity in cells transfected with variant-harboring PRKAR1B expression constructs.Our study provides strong evidence for a PRKAR1B-related neurodevelopmental disorder.
View details for DOI 10.1038/s41436-021-01152-7
View details for Web of Science ID 000638059400001
View details for PubMedID 33833410
Exome testing most useful for people with recessive CMT
WILEY. 2021: 141–42
View details for Web of Science ID 000626893200065
Commonalities across computational workflows for uncovering explanatory variants in undiagnosed cases.
Genetics in medicine : official journal of the American College of Medical Genetics
PURPOSE: Genomic sequencing has become an increasingly powerful and relevant tool to be leveraged for the discovery of genetic aberrations underlying rare, Mendelian conditions. Although the computational tools incorporated into diagnostic workflows for this task are continually evolving and improving, we nevertheless sought to investigate commonalities across sequencing processing workflows to reveal consensus and standard practice tools and highlight exploratory analyses where technical and theoretical method improvements would be most impactful.METHODS: We collected details regarding the computational approaches used by a genetic testing laboratory and 11 clinical research sites in the United States participating in the Undiagnosed Diseases Network via meetings with bioinformaticians, online survey forms, and analyses of internal protocols.RESULTS: We found that tools for processing genomic sequencing data can be grouped into four distinct categories. Whereas well-established practices exist for initial variant calling and quality control steps, there is substantial divergence across sites in later stages for variant prioritization and multimodal data integration, demonstrating a diversity of approaches for solving the most mysterious undiagnosed cases.CONCLUSION: The largest differences across diagnostic workflows suggest that advances in structural variant detection, noncoding variant interpretation, and integration of additional biomedical data may be especially promising for solving chronically undiagnosed cases.
View details for DOI 10.1038/s41436-020-01084-8
View details for PubMedID 33580225
Transcriptome alterations in myotonic dystrophy frontal cortex.
2021; 34 (3): 108634
Myotonic dystrophy (DM) is caused by expanded CTG/CCTG repeats, causing symptoms in skeletal muscle, heart, and central nervous system (CNS). CNS issues are debilitating and include hypersomnolence, executive dysfunction, white matter atrophy, and neurofibrillary tangles. Here, we generate RNA-seq transcriptomes from DM and unaffected frontal cortex and identify 130 high-confidence splicing changes, most occurring only in cortex, not skeletal muscle or heart. Mis-spliced exons occur in neurotransmitter receptors, ion channels, and synaptic scaffolds, and GRIP1 mis-splicing modulates kinesin association. Optical mapping of expanded CTG repeats reveals extreme mosaicism, with some alleles showing >1,000 CTGs. Mis-splicing severity correlates with CTG repeat length across individuals. Upregulated genes tend to be microglial and endothelial, suggesting neuroinflammation, and downregulated genes tend to be neuronal. Many gene expression changes strongly correlate with mis-splicing, suggesting candidate biomarkers of disease. These findings provide a framework for mechanistic and therapeutic studies of the DM CNS.
View details for DOI 10.1016/j.celrep.2020.108634
View details for PubMedID 33472074
Meta-analyses of ataluren randomized controlled trials in nonsense mutation Duchenne muscular dystrophy.
Journal of comparative effectiveness research
Aim: Assess the totality of efficacy evidence for ataluren inpatients withnonsense mutation Duchenne muscular dystrophy (nmDMD). Materials & methods: Data from the two completed randomized controlled trials (ClinicalTrials.gov: NCT00592553; NCT01826487) of ataluren in nmDMD were combined to examine the intent-to-treat (ITT) populations and two patient subgroups (baseline 6-min walk distance [6MWD] ≥300-<400 or <400m). Meta-analyses examined 6MWD change from baseline to week 48. Results: Statistically significant differences in 6MWD change with ataluren versus placebo were observed across all three meta-analyses. Least-squares mean difference (95% CI): ITT (n=342), +17.2 (0.2-34.1) m, p=0.0473; ≥300-<400m (n=143), +43.9 (18.2-69.6) m, p=0.0008; <400m (n=216), +27.7 (6.4-49.0) m, p=0.0109. Conclusion: These meta-analyses support previous evidence for ataluren in slowing disease progression versus placebo in patients with nmDMDover 48weeks. Treatment benefit was most evident in patients with a baseline 6MWD ≥300-<400m (the ambulatory transition phase), thereby informing future trial design.
View details for DOI 10.2217/cer-2020-0095
View details for PubMedID 32851872
Diagnosis of Myotonic Dystrophy Based on Resting State fMRI Using Convolutional Neural Networks.
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
2020; 2020: 1714–17
Myotonic dystrophies (DM) are neuromuscular conditions that cause widespread effects throughout the body. There are brain white matter changes on MRI in patients with DM that correlate with neuropsychological functional changes. How these brain alterations causally relate to the presence and severity of cognitive symptoms remains largely unknown. Deep neural networks have significantly improved the performance of image classification of huge datasets. However, its application in brain imaging is limited and not well described, due to the scarcity of labeled training data. In this work, we propose an approach for the diagnosis of DM based on a spatio-temporal deep learning paradigm. The obtained accuracy (73.71%) and sensitivities and specificities showed that the implemented approach based on 4-D convolutional neural networks leads to a compact, discriminative, and fast computing DM-based clinical medical decision support system.Clinical relevance- Many adults with DM experience cognitive and neurological effects impacting their quality of life, and ability to maintain employment. A robust and reliable DM-based clinical decision support system may help reduce the long diagnostic delay common to DM. Furthermore, it can help neurologists better understand the pathophysiology of the disease and analyze effects of new drugs that aim to address the neurological symptoms of DM.
View details for DOI 10.1109/EMBC44109.2020.9176455
View details for PubMedID 33018327
- Revised Recommendations for the Treatment of Infants Diagnosed with Spinal Muscular Atrophy Via Newborn Screening Who Have 4 Copies of SMN2. Journal of neuromuscular diseases 2020
Diagnosis of Myotonic Dystrophy Based on Resting State fMRI Using Convolutional Neural Networks
IEEE. 2020: 1714–17
View details for Web of Science ID 000621592202014
Successful liver transplantation in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).
Molecular genetics and metabolism
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a fatal disorder characterized by progressive gastrointestinal dysmotility, peripheral neuropathy, leukoencephalopathy, skeletal myopathy, ophthalmoparesis, and ptosis. MNGIE stems from deficient thymidine phosphorylase activity (TP) leading to toxic elevations of plasma thymidine. Hematopoietic stem cell transplant (HSCT) restores TP activity and halts disease progression but has high transplant-related morbidity and mortality. Liver transplant (LT) was reported to restore TP activity in two adult MNGIE patients. We report successful LT in four additional MNGIE patients, including a pediatric patient. Our patients were diagnosed between ages 14 months and 36 years with elevated thymidine levels and biallelic pathogenic variants in TYMP. Two patients presented with progressive gastrointestinal dysmotility, and three demonstrated progressive peripheral neuropathy with two suffering limitations in ambulation. Two patients, including the child, had liver dysfunction and cirrhosis. Following LT, thymidine levels nearly normalized in all four patients and remained low for the duration of follow-up. Disease symptoms stabilized in all patients, with some manifesting improvements, including intestinal function. No patient died, and LT appeared to have a more favorable safety profile than HSCT, especially when liver disease is present. Follow-up studies will need to document the long-term impact of this new approach on disease outcome. Take Home Message: Liver transplantation is effective in stabilizing symptoms and nearly normalizing thymidine levels in patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and may have an improved safety profile over hematopoietic stem cell transplant.
View details for DOI 10.1016/j.ymgme.2020.03.001
View details for PubMedID 32173240
Clinical sites of the Undiagnosed Diseases Network: unique contributions to genomic medicine and science.
Genetics in medicine : official journal of the American College of Medical Genetics
The NIH Undiagnosed Diseases Network (UDN) evaluates participants with disorders that have defied diagnosis, applying personalized clinical and genomic evaluations and innovative research. The clinical sites of the UDN are essential to advancing the UDN mission; this study assesses their contributions relative to standard clinical practices.We analyzed retrospective data from four UDN clinical sites, from July 2015 to September 2019, for diagnoses, new disease gene discoveries and the underlying investigative methods.Of 791 evaluated individuals, 231 received 240 diagnoses and 17 new disease-gene associations were recognized. Straightforward diagnoses on UDN exome and genome sequencing occurred in 35% (84/240). We considered these tractable in standard clinical practice, although genome sequencing is not yet widely available clinically. The majority (156/240, 65%) required additional UDN-driven investigations, including 90 diagnoses that occurred after prior nondiagnostic exome sequencing and 45 diagnoses (19%) that were nongenetic. The UDN-driven investigations included complementary/supplementary phenotyping, innovative analyses of genomic variants, and collaborative science for functional assays and animal modeling.Investigations driven by the clinical sites identified diagnostic and research paradigms that surpass standard diagnostic processes. The new diagnoses, disease gene discoveries, and delineation of novel disorders represent a model for genomic medicine and science.
View details for DOI 10.1038/s41436-020-00984-z
View details for PubMedID 33093671
De novo EIF2AK1 and EIF2AK2 Variants Are Associated with Developmental Delay, Leukoencephalopathy, and Neurologic Decompensation.
American journal of human genetics
EIF2AK1 and EIF2AK2 encode members of the eukaryotic translation initiation factor 2 alpha kinase (EIF2AK) family that inhibits protein synthesis in response to physiologic stress conditions. EIF2AK2 is also involved in innate immune response and the regulation of signal transduction, apoptosis, cell proliferation, and differentiation. Despite these findings, human disorders associated with deleterious variants in EIF2AK1 and EIF2AK2 have not been reported. Here, we describe the identification of nine unrelated individuals with heterozygous de novo missense variants in EIF2AK1 (1/9) or EIF2AK2 (8/9). Features seen in these nine individuals include white matter alterations (9/9), developmental delay (9/9), impaired language (9/9), cognitive impairment (8/9), ataxia (6/9), dysarthria in probands with verbal ability (6/9), hypotonia (7/9), hypertonia (6/9), and involuntary movements (3/9). Individuals with EIF2AK2 variants also exhibit neurological regression in the setting of febrile illness or infection. We use mammalian cell lines and proband-derived fibroblasts to further confirm the pathogenicity of variants in these genes and found reduced kinase activity. EIF2AKs phosphorylate eukaryotic translation initiation factor 2 subunit 1 (EIF2S1, also known as EIF2α), which then inhibits EIF2B activity. Deleterious variants in genes encoding EIF2B proteins cause childhood ataxia with central nervous system hypomyelination/vanishing white matter (CACH/VWM), a leukodystrophy characterized by neurologic regression in the setting of febrile illness and other stressors. Our findings indicate that EIF2AK2 missense variants cause a neurodevelopmental syndrome that may share phenotypic and pathogenic mechanisms with CACH/VWM.
View details for DOI 10.1016/j.ajhg.2020.02.016
View details for PubMedID 32197074
Multiomics Approach to Diagnosing Undiagnosed Patients
NATURE PUBLISHING GROUP. 2019: 1163–64
View details for Web of Science ID 000489313900224
Connexin43 is Dispensable for Early Stage Human Mesenchymal Stem Cell Adipogenic Differentiation But is Protective against Cell Senescence.
2019; 9 (9)
In the last couple of decades, there has been a growing optimism surrounding the potential transformative use of human mesenchymal stem cells (MSCs) and human-induced pluripotent stem cells (iPSCs) for regenerative medicine and disease treatment. In order for this to occur, it is first essential to understand the mechanisms underpinning their cell-fate specification, which includes cell signaling via gap junctional intercellular communication. Here, we investigated the role of the prototypical gap junction protein, connexin43 (Cx43), in governing the differentiation of iPSCs into MSCs and MSC differentiation along the adipogenic lineage. We found that control iPSCs, as well as iPSCs derived from oculodentodigital dysplasia patient fibroblasts harboring a GJA1 (Cx43) gene mutation, successfully and efficiently differentiated into LipidTox and perilipin-positive cells, indicating cell differentiation along the adipogenic lineage. Furthermore, the complete CRISPR-Cas9 ablation of Cx43 from iPSCs did not prevent their differentiation into bona fide MSCs or pre-adipocytes, strongly suggesting that even though Cx43 expression is upregulated during adipogenesis, it is expendable. Interestingly, late passage Cx43-ablated MSCs senesced more quickly than control cells, resulting in failure to properly differentiate in vitro. We conclude that despite being upregulated during adipogenesis, Cx43 plays no detectable role in the early stages of human iPSC-derived MSC adipogenic differentiation. However, Cx43 may play a more impactful role in protecting MSCs from premature senescence.
View details for DOI 10.3390/biom9090474
View details for PubMedID 31514306
Explaining RLS families using risk SNPs from GWAS
NATURE PUBLISHING GROUP. 2019: 658–59
View details for Web of Science ID 000489313105076
- Extracutaneous manifestations in phacomatosis cesioflammea and cesiomarmorata: Case series and literature review AMERICAN JOURNAL OF MEDICAL GENETICS PART A 2019; 179 (6): 966–77
- A Patient with Sjogren's Syndrome and Subsequent Diagnosis of Inclusion Body Myositis and Light-Chain Amyloidosis JOURNAL OF GENERAL INTERNAL MEDICINE 2019; 34 (6): 1058–62
Nusinersen Efficacy in Adults with Spinal Muscular Atrophy
LIPPINCOTT WILLIAMS & WILKINS. 2019
View details for Web of Science ID 000475965907110
Treatment Algorithm for Infants Diagnosed with Spinal Muscular Atrophy Through Newborn Screening
LIPPINCOTT WILLIAMS & WILKINS. 2019
View details for Web of Science ID 000475965900291
- Developing a genomics rotation: Practical training around variant interpretation for genetic counseling students JOURNAL OF GENETIC COUNSELING 2019; 28 (2): 466–76
- A toolkit for genetics providers in follow-up of patients with non-diagnostic exome sequencing JOURNAL OF GENETIC COUNSELING 2019; 28 (2): 213–28
Extracutaneous manifestations in phacomatosis cesioflammea and cesiomarmorata: Case series and literature review.
American journal of medical genetics. Part A
Phacomatosis pigmentovascularis (PPV) comprises a family of rare conditions that feature vascular abnormalities and melanocytic lesions that can be solely cutaneous or multisystem in nature. Recently published work has demonstrated that both vascular and melanocytic abnormalities in PPV of the cesioflammea and cesiomarmorata subtypes can result from identical somatic mosaic activating mutations in the genes GNAQ and GNA11. Here, we present three new cases of PPV with features of the cesioflammea and/or cesiomarmorata subtypes and mosaic mutations in GNAQ or GNA11. To better understand the risk of potentially occult complications faced by such patients we additionally reviewed 176 cases published in the literature. We report the frequency of clinical findings, their patterns of co-occurrence as well as published recommendations for surveillance after diagnosis. Features assessed include: capillary malformation; dermal and ocular melanocytosis; glaucoma; limb asymmetry; venous malformations; and central nervous system (CNS) anomalies, such as ventriculomegaly and calcifications. We found that ocular findings are common in patients with phacomatosis cesioflammea and cesiomarmorata. Facial vascular involvement correlates with a higher risk of seizures (p=.0066). Our genetic results confirm the role of mosaic somatic mutations in GNAQ and GNA11 in phacomatosis cesioflammea and cesiomarmorata. Their clinical and molecular findings place these conditions on a clinical spectrum encompassing other GNAQ and GNA11 related disorders and inform recommendations for their management.
View details for PubMedID 30920161
Dynamic regulation of connexins in stem cell pluripotency.
Stem cells (Dayton, Ohio)
Characterization of the pluripotent "ground state" has led to a greater understanding of species-specific stem cell differences and has imparted an appreciation of the pluripotency continuum that exists in stem cells in vitro. Pluripotent stem cells are functionally coupled via connexins that serve in gap junctional intercellular communication (GJIC) and here we report that the level of connexin expression in pluripotent stem cells depends upon the state in which stem cells exist in vitro. Human and mouse pluripotent stem cells stabilized in a developmentally primitive or "naïve" state exhibit significantly less connexin expression compared with stem cells which are "primed" for differentiation. This dynamic connexin expression pattern may be governed, in part, by differential regulation by pluripotency transcription factors expressed in each cell state. Species-specific differences do exist however, with mouse stem cells expressing several additional connexin transcripts not found in human pluripotent stem cells. Moreover, pharmacological inhibition of GJIC shows limited impact on naïve human stem cell survival, self-renewal, and pluripotency but plays a more significant role in primed human pluripotent stem cells. However, CRISPR-Cas9 gene ablation of Cx43 in human and mouse primed and naïve pluripotent stem cells reveals that Cx43 is dispensable in each of these four pluripotent stem cell types. Stem Cells 2019.
View details for DOI 10.1002/stem.3092
View details for PubMedID 31646713
Genomics in medicine: a novel elective rotation for internal medicine residents.
Postgraduate medical journal
It is well recognised that medical training globally and at all levels lacks sufficient incorporation of genetics and genomics education to keep up with the rapid advances and growing application of genomics to clinical care. However, the best strategy to implement these desired changes into postgraduate medical training and engage learners is still unclear. We developed a novel elective rotation in 'Genomic Medicine and Undiagnosed Diseases' for categorical Internal Medicine Residents to address this educational gap and serve as an adaptable model for training that can be applied broadly across different specialties and at other institutions. Key curriculum goals achieved include increased understanding about genetic testing modalities and tools available for diagnosis and risk analysis, the role of genetics-trained allied health professionals, and indications and limitations of genetic and genomic testing in both rare and common conditions.
View details for DOI 10.1136/postgradmedj-2018-136355
View details for PubMedID 31439813
A toolkit for genetics providers in follow-up of patients with non-diagnostic exome sequencing.
Journal of genetic counseling
2019; 28 (2): 213–28
There are approximately 7,000 rare diseases affecting 25-30 million Americans, with 80% estimated to have a genetic basis. This presents a challenge for genetics practitioners to determine appropriate testing, make accurate diagnoses, and conduct up-to-date patient management. Exome sequencing (ES) is a comprehensive diagnostic approach, but only 25%-41% of the patients receive a molecular diagnosis. The remaining three-fifths to three-quarters of patients undergoing ES remain undiagnosed. The Stanford Center for Undiagnosed Diseases (CUD), a clinical site of the Undiagnosed Diseases Network, evaluates patients with undiagnosed and rare diseases using a combination of methods including ES. Frequently these patients have non-diagnostic ES results, but strategic follow-up techniques identify diagnoses in a subset. We present techniques used at the CUD that can be adopted by genetics providers in clinical follow-up of cases where ES is non-diagnostic. Solved case examples illustrate different types of non-diagnostic results and the additional techniques that led to a diagnosis. Frequent approaches include segregation analysis, data reanalysis, genome sequencing, additional variant identification, careful phenotype-disease correlation, confirmatory testing, and case matching. We also discuss prioritization of cases for additional analyses.
View details for PubMedID 30964584
A Patient with Sjogren's Syndrome and Subsequent Diagnosis of Inclusion Body Myositis and Light-Chain Amyloidosis.
Journal of general internal medicine
We discuss a challenging case of a 58-year-old Vietnamese-American woman who presented to her new primary care provider with an 8-year history of slowly progressive dysphagia, hoarseness, muscle weakness with associated frequent falls, and weight loss. She eventually reported dry eyes and dry mouth, and she was diagnosed with Sjogren's syndrome. Subsequently, she was additionally diagnosed with inclusion body myositis and gastric light-chain (AL) amyloidosis. Although inclusion body myositis has been previously associated with Sjogren's syndrome, inclusion body myositis is rare in non-Caucasians, and the trio of Sjogren's syndrome, inclusion body myositis, and AL amyloidosis has not been previously reported. Sjogren's syndrome is a systemic autoimmune condition characterized by ocular and oral dryness. It is one of the most common rheumatologic disorders in the USA and worldwide. Early diagnosis of Sjogren's is particularly important given the frequency and variety of associated autoimmune diseases and extraglandular manifestations. Furthermore, although inclusion body myositis has a low prevalence, it is the most common inflammatory myopathy in older adults and is unfortunately associated with long delays in diagnosis, so knowledge of this disorder is also crucial for practicing internists.
View details for PubMedID 30887439
Identification of rare-disease genes using blood transcriptome sequencing and large control cohorts.
It is estimated that 350 million individuals worldwide suffer from rare diseases, which are predominantly caused by mutation in a single gene1. The current molecular diagnostic rate is estimated at 50%, with whole-exome sequencing (WES) among the most successful approaches2-5. For patients in whom WES is uninformative, RNA sequencing (RNA-seq) has shown diagnostic utility in specific tissues and diseases6-8. This includes muscle biopsies from patients with undiagnosed rare muscle disorders6,9, and cultured fibroblasts from patients with mitochondrial disorders7. However, for many individuals, biopsies are not performed for clinical care, and tissues are difficult to access. We sought to assess the utility of RNA-seq from blood as a diagnostic tool for rare diseases of different pathophysiologies. We generated whole-blood RNA-seq from 94 individuals with undiagnosed rare diseases spanning 16 diverse disease categories. We developed a robust approach to compare data from these individuals with large sets of RNA-seq data for controls (n = 1,594 unrelated controls and n = 49 family members) and demonstrated the impacts of expression, splicing, gene and variant filtering strategies on disease gene identification. Across our cohort, we observed that RNA-seq yields a 7.5% diagnostic rate, and an additional 16.7% with improved candidate gene resolution.
View details for DOI 10.1038/s41591-019-0457-8
View details for PubMedID 31160820
Developing a genomics rotation: Practical training around variant interpretation for genetic counseling students.
Journal of genetic counseling
With the wide adoption of next-generation sequencing (NGS)-based genetic tests, genetic counselors require increased familiarity with NGS technology, variant interpretation concepts, and variant assessment tools. The use of exome and genome sequencing in clinical care has expanded the reach and diversity of genetic testing. Regardless of the setting where genetic counselors are performing variant interpretation or reporting, most of them have learned these skills from colleagues, while on the job. Though traditional, lecture-based learning around these topics is important, there has been growing need for the inclusion of case-based, experiential training of genomics and variant interpretation for genetic counseling students, with the goal of creating a strong foundation in variant interpretation for new genetic counselors, regardless of what area of practice they enter. To address this need, we established a genomics and variant interpretation rotation for Stanford's genetic counseling training program. In response to changes in the genomics landscape, this has now evolved into three unique rotation experiences, each focused on variant interpretation in the context of various genomic settings, including clinical laboratory, research laboratory, and healthy genomic analysis studies. Here, we describe the goals and learning objectives that we have developed for these variant interpretation rotations, and illustrate how these concepts are applied in practice.
View details for PubMedID 30706981
Consensus-based care recommendations for adults with myotonic dystrophy type 1
2018; 8 (6): 507–20
Myotonic dystrophy type 1 (DM1) is a severe, progressive genetic disease that affects between 1 in 3,000 and 8,000 individuals globally. No evidence-based guideline exists to inform the care of these patients, and most do not have access to multidisciplinary care centers staffed by experienced professionals, creating a clinical care deficit.The Myotonic Dystrophy Foundation (MDF) recruited 66 international clinicians experienced in DM1 patient care to develop consensus-based care recommendations. MDF created a 2-step methodology for the project using elements of the Single Text Procedure and the Nominal Group Technique. The process generated a 4-page Quick Reference Guide and a comprehensive, 55-page document that provides clinical care recommendations for 19 discrete body systems and/or care considerations.The resulting recommendations are intended to help standardize and elevate care for this patient population and reduce variability in clinical trial and study environments.
View details for DOI 10.1212/CPJ.0000000000000531
View details for Web of Science ID 000456290100016
View details for PubMedID 30588381
View details for PubMedCentralID PMC6294540
- Minimally Invasive Thymectomy and Lung Volume Reduction in a Patient With Myasthenia Gravis ANNALS OF THORACIC SURGERY 2018; 106 (6): E313–E315
- Effect of Genetic Diagnosis on Patients with Previously Undiagnosed Disease NEW ENGLAND JOURNAL OF MEDICINE 2018; 379 (22): 2131–39
C-terminal proline deletions in KCNC3 cause delayed channel inactivation and an adult-onset progressive SCA13 with spasticity
2018; 17 (5): 692–97
Mutations in the potassium channel gene KCNC3 (Kv3.3) cause the autosomal dominant neurological disease, spinocerebellar ataxia 13 (SCA13). In this study, we expand the genotype-phenotype repertoire of SCA13 by describing the novel KCNC3 deletion p.Pro583_Pro585del highlighting the allelic heterogeneity observed in SCA13 patients. We characterize adult-onset, progressive clinical symptoms of two afflicted kindred and introduce the symptom of profound spasticity not previously associated with the SCA13 phenotype. We also present molecular and electrophysiological characterizations of the mutant protein in mammalian cell culture. Mechanistically, the p.Pro583_Pro585del protein showed normal membrane trafficking with an altered electrophysiological profile, including slower inactivation and decreased sensitivity to the inactivation-accelerating effects of the actin depolymerizer latrunculin B. Taken together, our results highlight the clinical importance of the intracellular C-terminal portion of Kv3.3 and its association with ion channel function.
View details for PubMedID 29949095
- Experience using Spinraza to treat adults with spinal muscular atrophy PERGAMON-ELSEVIER SCIENCE LTD. 2018: S81
FGFR3 Antibodies in Neuropathy: What to Do With Them?
Journal of clinical neuromuscular disease
2018; 20 (1): 35–40
OBJECTIVES: To describe the variability of fibroblast growth factor receptor 3 (FGFR3) antibody titers in a small series of patients.METHODS: We performed a retrospective review of patients with neuropathy and positive FGFR3 antibodies.RESULTS: We report 7 patients (3 women) with an age range 44-81 years. Symptoms were acute onset in 3 and subacute onset in 4 patients. Five had neuropathic pain. Examination revealed normal large fiber function to mild/moderate predominantly sensory neuropathy and ataxia in one patient. Electrodiagnostic studies revealed normal large fiber function (3), demyelinating neuropathy (1), and mild/moderate axonal neuropathy (3). Four patients had high and 3 patients had low FGFR3 titers. Repeat testing revealed absence of antibodies in 2 patients and a significant reduction in one patient without any intervening immunotherapy.CONCLUSIONS: Our case series highlights the variability and inconsistency in FGFR3 antibody titers through enzyme-linked immunosorbent assay testing. These antibody titers should always be interpreted with caution in clinical context.
View details for DOI 10.1097/CND.0000000000000221
View details for PubMedID 30124558
Minimally Invasive Thymectomy and Lung Volume Reduction in a Patient with Myasthenia Gravis.
The Annals of thoracic surgery
We describe the case of a patient with myasthenia gravis and severe pulmonary emphysema who underwent concomitant bilateral video/robotic-assisted thymectomy with unilateral lung volume reduction surgery. We review the important pathophysiological considerations that must be appreciated to ensure safe surgery in this unusual situation with two diseases that independently affect the respiratory system - each of which requires preoperative optimization.
View details for PubMedID 29807007
FGFR3 Antibodies in Neuropathy. What to do with them?
LIPPINCOTT WILLIAMS & WILKINS. 2018
View details for Web of Science ID 000453090800443
Nusinersen Efficacy in Adults with Spinal Muscular Atrophy
LIPPINCOTT WILLIAMS & WILKINS. 2018
View details for Web of Science ID 000453090806001
Nusinersen versus Sham Control in Later-Onset Spinal Muscular Atrophy
NEW ENGLAND JOURNAL OF MEDICINE
2018; 378 (7): 625–35
Nusinersen is an antisense oligonucleotide drug that modulates pre-messenger RNA splicing of the survival motor neuron 2 ( SMN2) gene. It has been developed for the treatment of spinal muscular atrophy (SMA).We conducted a multicenter, double-blind, sham-controlled, phase 3 trial of nusinersen in 126 children with SMA who had symptom onset after 6 months of age. The children were randomly assigned, in a 2:1 ratio, to undergo intrathecal administration of nusinersen at a dose of 12 mg (nusinersen group) or a sham procedure (control group) on days 1, 29, 85, and 274. The primary end point was the least-squares mean change from baseline in the Hammersmith Functional Motor Scale-Expanded (HFMSE) score at 15 months of treatment; HFMSE scores range from 0 to 66, with higher scores indicating better motor function. Secondary end points included the percentage of children with a clinically meaningful increase from baseline in the HFMSE score (≥3 points), an outcome that indicates improvement in at least two motor skills.In the prespecified interim analysis, there was a least-squares mean increase from baseline to month 15 in the HFMSE score in the nusinersen group (by 4.0 points) and a least-squares mean decrease in the control group (by -1.9 points), with a significant between-group difference favoring nusinersen (least-squares mean difference in change, 5.9 points; 95% confidence interval, 3.7 to 8.1; P<0.001). This result prompted early termination of the trial. Results of the final analysis were consistent with results of the interim analysis. In the final analysis, 57% of the children in the nusinersen group as compared with 26% in the control group had an increase from baseline to month 15 in the HFMSE score of at least 3 points (P<0.001), and the overall incidence of adverse events was similar in the nusinersen group and the control group (93% and 100%, respectively).Among children with later-onset SMA, those who received nusinersen had significant and clinically meaningful improvement in motor function as compared with those in the control group. (Funded by Biogen and Ionis Pharmaceuticals; CHERISH ClinicalTrials.gov number, NCT02292537 .).
View details for PubMedID 29443664
Increased EEG Theta Spectral Power in Sleep in Myotonic Dystrophy Type 1.
Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine
2018; 14 (2): 229–35
Myotonic dystrophy type 1 (DM1) is a multisystemic disorder that involves the central nervous system (CNS). Individuals with DM1 commonly present with sleep dysregulation, including excessive daytime sleepiness and sleep-disordered breathing. We aim to characterize electroencephalogram (EEG) power spectra from nocturnal polysomnography (PSG) in patients with DM1 compared to matched controls to better understand the potential CNS sleep dysfunction in DM1.A retrospective, case-control (1:2) chart review of patients with DM1 (n = 18) and matched controls (n = 36) referred for clinical PSG at the Stanford Sleep Center was performed. Controls were matched based on age, sex, apnea-hypopnea index (AHI), body mass index (BMI), and Epworth Sleepiness Scale (ESS). Sleep stage and respiratory metrics for the two groups were compared. Power spectral analysis of the EEG C3-M2 signal was performed using the fast Fourier transformation.Patients with DM1 had significantly increased theta percent power in stage N2 sleep compared to matched controls. Theta/beta and theta/alpha percent power spectral ratios were found to be significantly increased in stage N2, N3, all sleep stages combined, and all wake periods combined in patients with DM1 compared to controls. A significantly lower nadir O2saturation was also found in patients with DM1 versus controls.Compared to matched controls, patients with DM1 had increased EEG theta spectral power. Increased theta/beta and theta/alpha power spectral ratios in nocturnal PSG may reflect DM1 pathology in the CNS.
View details for PubMedID 29394960
Treatment Algorithm for Infants Diagnosed with Spinal Muscular Atrophy through Newborn Screening.
Journal of neuromuscular diseases
2018; 5 (2): 145–58
BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by the degeneration of alpha motor neurons in the spinal cord, leading to muscular atrophy. SMA is caused by deletions or mutations in the survival motor neuron 1 gene (SMN1). In humans, a nearly identical copy gene, SMN2, is present. Because SMN2 has been shown to decrease disease severity in a dose-dependent manner, SMN2 copy number is predictive of disease severity.OBJECTIVE: To develop a treatment algorithm for SMA-positive infants identified through newborn screening based upon SMN2 copy number.METHODS: A working group comprised of 15 SMA experts participated in a modified Delphi process, moderated by a neutral third-party expert, to develop treatment guidelines.RESULTS: The overarching recommendation is that all infants with two or three copies of SMN2 should receive immediate treatment (n = 13). For those infants in which immediate treatment is not recommended, guidelines were developed that outline the timing and appropriate screens and tests to be used to determine the timing of treatment initiation.CONCLUSIONS: The identification SMA affected infants via newborn screening presents an unprecedented opportunity for achievement of maximal therapeutic benefit through the administration of treatment pre-symptomatically. The recommendations provided here are intended to help formulate treatment guidelines for infants who test positive during the newborn screening process.
View details for PubMedID 29614695
Effect of Genetic Diagnosis on Patients with Previously Undiagnosed Disease.
The New England journal of medicine
Many patients remain without a diagnosis despite extensive medical evaluation. The Undiagnosed Diseases Network (UDN) was established to apply a multidisciplinary model in the evaluation of the most challenging cases and to identify the biologic characteristics of newly discovered diseases. The UDN, which is funded by the National Institutes of Health, was formed in 2014 as a network of seven clinical sites, two sequencing cores, and a coordinating center. Later, a central biorepository, a metabolomics core, and a model organisms screening center were added.We evaluated patients who were referred to the UDN over a period of 20 months. The patients were required to have an undiagnosed condition despite thorough evaluation by a health care provider. We determined the rate of diagnosis among patients who subsequently had a complete evaluation, and we observed the effect of diagnosis on medical care.A total of 1519 patients (53% female) were referred to the UDN, of whom 601 (40%) were accepted for evaluation. Of the accepted patients, 192 (32%) had previously undergone exome sequencing. Symptoms were neurologic in 40% of the applicants, musculoskeletal in 10%, immunologic in 7%, gastrointestinal in 7%, and rheumatologic in 6%. Of the 382 patients who had a complete evaluation, 132 received a diagnosis, yielding a rate of diagnosis of 35%. A total of 15 diagnoses (11%) were made by clinical review alone, and 98 (74%) were made by exome or genome sequencing. Of the diagnoses, 21% led to recommendations regarding changes in therapy, 37% led to changes in diagnostic testing, and 36% led to variant-specific genetic counseling. We defined 31 new syndromes.The UDN established a diagnosis in 132 of the 382 patients who had a complete evaluation, yielding a rate of diagnosis of 35%. (Funded by the National Institutes of Health Common Fund.).
View details for PubMedID 30304647
Increased EEG theta spectral power in polysomnography of myotonic dystrophy type 1 compared to matched controls.
LIPPINCOTT WILLIAMS & WILKINS. 2017
View details for Web of Science ID 000577381503279
Loss-of-Function Mutations in LGI4, a Secreted Ligand Involved in Schwann Cell Myelination, Are Responsible for Arthrogryposis Multiplex Congenita
AMERICAN JOURNAL OF HUMAN GENETICS
2017; 100 (4): 659-665
Arthrogryposis multiplex congenita (AMC) is a developmental condition characterized by multiple joint contractures resulting from reduced or absent fetal movements. Through genetic mapping of disease loci and whole-exome sequencing in four unrelated multiplex families presenting with severe AMC, we identified biallelic loss-of-function mutations in LGI4 (leucine-rich glioma-inactivated 4). LGI4 is a ligand secreted by Schwann cells that regulates peripheral nerve myelination via its cognate receptor ADAM22 expressed by neurons. Immunolabeling experiments and transmission electron microscopy of the sciatic nerve from one of the affected individuals revealed a lack of myelin. Functional tests using affected individual-derived iPSCs showed that these germline mutations caused aberrant splicing of the endogenous LGI4 transcript and in a cell-based assay impaired the secretion of truncated LGI4 protein. This is consistent with previous studies reporting arthrogryposis in Lgi4-deficient mice due to peripheral hypomyelination. This study adds to the recent reports implicating defective axoglial function as a key cause of AMC.
View details for DOI 10.1016/j.ajhg.2017.02.006
View details for PubMedID 28318499
- A 31-Year-Old Man With a Ring-Enhancing Brain Lesion. Journal of neuro-ophthalmology 2017
- Basal Ganglia Gliosis in a Case of Rapid-Onset Dystonia-Parkinsonism (DYT12) with a Novel Mutation in ATPase 1A3 (ATP1A3) MOVEMENT DISORDERS CLINICAL PRACTICE 2016; 3 (6): 618–20
Specific functional pathologies of Cx43 mutations associated with oculodentodigital dysplasia.
Molecular biology of the cell
2016; 27 (14): 2172-2185
Oculodentodigital dysplasia (ODDD) is a rare genetic disease that affects the development of multiple organs in the human body. More than 70 mutations in the gap junction connexin43 (Cx43) gene, GJA1, are associated with ODDD, most of which are inherited in an autosomal dominant manner. Many patients exhibit similar clinical presentations. However, there is high intrafamilial and interfamilial phenotypic variability. To better understand this variability, we established primary human dermal fibroblast cultures from several ODDD patients and unaffected controls. In the present study, we characterized three fibroblast lines expressing heterozygous p.L7V, p.G138R, and p.G143S Cx43 variants. All ODDD fibroblasts exhibited slower growth, reduced migration, and defective cell polarization, traits common to all ODDD fibroblasts studied so far. However, we found striking differences in overall expression levels, with p.L7V down-regulated at the mRNA and protein level. Although all of the Cx43 variants could traffic to the cell surface, there were stark differences in gap junction plaque formation, gap junctional intercellular communication, Cx43 phosphorylation, and hemichannel activity among Cx43 variants, as well as subtle differences in myofibroblast differentiation. Together these findings enabled us to discover mutation-specific pathologies that may help to predict future clinical outcomes.
View details for DOI 10.1091/mbc.E16-01-0062
View details for PubMedID 27226478
Basal Ganglia Gliosis in a Case of Rapid-Onset Dystonia-Parkinsonism (DYT12) with a Novel Mutation in ATPase 1A3 (ATP1A3).
Movement disorders clinical practice
2016; 3 (6): 618–20
View details for PubMedID 30838256
Manipulating Cx43 expression triggers gene reprogramming events in dermal fibroblasts from oculodentodigital dysplasia patients.
2015; 472 (1): 55-69
Oculodentodigital dysplasia (ODDD) is primarily an autosomal dominant disorder linked to over 70 GJA1 gene [connexin43 (Cx43)] mutations. For nearly a decade, our laboratory has been investigating the relationship between Cx43 and ODDD by expressing disease-linked mutants in reference cells, tissue-relevant cell lines, 3D organ cultures and by using genetically modified mouse models of human disease. Although salient features of Cx43 mutants have been revealed, these models do not necessarily reflect the complexity of the human context. To further overcome these limitations, we have acquired dermal fibroblasts from two ODDD-affected individuals harbouring D3N and V216L mutations in Cx43, along with familial controls. Using these ODDD patient dermal fibroblasts, which naturally produce less GJA1 gene product, along with RNAi and RNA activation (RNAa) approaches, we show that manipulating Cx43 expression triggers cellular gene reprogramming. Quantitative RT-PCR, Western blot and immunofluorescent analysis of ODDD patient fibroblasts show unusually high levels of extracellular matrix (ECM)-interacting proteins, including integrin α5β1, matrix metalloproteinases as well as secreted ECM proteins collagen-I and laminin. Cx43 knockdown in familial control cells produces similar effects on ECM expression, whereas Cx43 transcriptional up-regulation using RNAa decreases production of collagen-I. Interestingly, the enhanced levels of ECM-associated proteins in ODDD V216L fibroblasts is not only a consequence of increased ECM gene expression, but also due to an apparent deficit in collagen-I secretion which may further contribute to impaired collagen gel contraction in ODDD fibroblasts. These findings further illuminate the altered function of Cx43 in ODDD-affected individuals and highlight the impact of manipulating Cx43 expression in human cells.
View details for DOI 10.1042/BJ20150652
View details for PubMedID 26349540
Modeling Cx43-linked pathologies in the human context
AMER SOC CELL BIOLOGY. 2015
View details for Web of Science ID 000209928600480
Nuclear localization of SMN and FUS is not altered in fibroblasts from patients with sporadic ALS
AMYOTROPHIC LATERAL SCLEROSIS AND FRONTOTEMPORAL DEGENERATION
2014; 15 (7-8): 581-587
Abstract Sporadic amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with no established biological marker. Recent observation of a reduced number of gems (survival motor neuron protein (SMN)-positive nuclear bodies) in cells from patients with familial ALS and the mouse models suggests an involvement of SMN in ALS pathology. At a molecular level, fused in sarcoma (FUS), one of the familial ALS-linked proteins, has been demonstrated to directly interact with SMN, while impaired nuclear localization of mutated FUS causes defective gem formation. Our objective was to determine whether gems and/or nuclear FUS levels in skin derived fibroblasts from sporadic ALS patients are consistently reduced and thus could constitute a novel and readily available biomarker of the disease. Fibroblasts from 20 patients and 17 age-matched healthy controls were cultured and co-immunostained for SMN and FUS. Results showed that no difference was detected between the two groups in the number of gems and in expression pattern of FUS. The number of gems negatively correlated with the age at biopsy in both ALS and control subjects. In conclusion, the expression pattern of SMN and FUS in fibroblasts cannot serve as a biomarker for sporadic ALS. Donor age-dependent gem reduction is a novel observation that links SMN with cellular senescence.
View details for DOI 10.3109/21678421.2014.907319
View details for Web of Science ID 000346926100017
View details for PubMedID 24809826
ATALUREN TREATMENT OF PATIENTS WITH NONSENSE MUTATION DYSTROPHINOPATHY
MUSCLE & NERVE
2014; 50 (4): 477-487
Dystrophinopathy is a rare, severe muscle disorder, and nonsense mutations are found in 13% of cases. Ataluren was developed to enable ribosomal readthrough of premature stop codons in nonsense mutation (nm) genetic disorders.Randomized, double-blind, placebo-controlled study; males ≥5 years with nm-dystrophinopathy received study drug orally 3 times daily, ataluren 10, 10, 20 mg/kg (N = 57); ataluren 20, 20, 40 mg/kg (N = 60); or placebo (N = 57) for 48 weeks. The primary endpoint was change in 6-Minute Walk Distance (6MWD) at Week 48.Ataluren was generally well tolerated. The primary endpoint favored ataluren 10, 10, 20 mg/kg versus placebo; the week 48 6MWD Δ = 31.3 meters, post hoc P = 0.056. Secondary endpoints (timed function tests) showed meaningful differences between ataluren 10, 10, 20 mg/kg, and placebo.As the first investigational new drug targeting the underlying cause of nm-dystrophinopathy, ataluren offers promise as a treatment for this orphan genetic disorder with high unmet medical need. Muscle Nerve 50: 477-487, 2014.
View details for DOI 10.1002/mus.24332
View details for Web of Science ID 000342634100002
View details for PubMedID 25042182
The G60S Cx43 mutant enhances keratinocyte proliferation and differentiation
2012; 21 (8): 612-618
Transient knock-down of the gap junction protein Cx43 by antisense and siRNA, or gap junction block with mimetic peptides, have been shown to enhance epidermal wound healing. However, patients with oculodentodigital dysplasia (ODDD) express mutant Cx43 that leads to a chronic reduction in gap junctional intercellular communication. To determine whether mutant Cx43 in keratinocytes would impact upon the wound healing process, we localized Cx43 in human and mouse skin tissue expressing mutant Cx43 and assessed the ability of primary keratinocytes derived from a mouse model of ODDD to proliferate, migrate and differentiate. In the epidermis from an ODDD patient and in the epidermis of mice expressing the G60S mutant or in keratinocytes obtained from mutant mice, Cx43 was frequently found within intracellular compartments and rarely localized to punctate sites of cell-cell apposition. Primary keratinocytes derived from G60S mutant mice proliferated faster but migrated similarly to keratinocytes derived from wild-type control mice. Keratinocytes derived from mutant mice expressed abundant Cx43 and higher levels of involucrin and loricrin under low calcium conditions. However, after calcium-induced differentiation, similar levels of Cx43, involucrin and loricrin were observed. Thus, we conclude that during wound healing, mutant Cx43 may enhance keratinocyte proliferation and promote early differentiation of keratinocytes.
View details for DOI 10.1111/j.1600-0625.2012.01532.x
View details for Web of Science ID 000306222700009
View details for PubMedID 22775996
Human Dermal Fibroblasts Derived from Oculodentodigital Dysplasia Patients Suggest That Patients May Have Wound-Healing Defects
2011; 32 (4): 456-466
Oculodentodigital dysplasia (ODDD) is primarily an autosomal dominant human disease caused by any one of over 60 mutations in the GJA1 gene encoding the gap junction protein Cx43. In the present study, wound healing was investigated in a G60S ODDD mutant mouse model and by using dermal fibroblasts isolated from two ODDD patients harboring the p.D3N and p.V216L mutants along with dermal fibroblasts isolated from their respective unaffected relatives. Punch biopsies revealed a delay in wound closure in the G60S mutant mice in comparison to wild-type littermates, and this delay appeared to be due to defects in the dermal fibroblasts. Although both the p.D3N and p.V216L mutants reduced gap junctional intercellular communication in human dermal fibroblasts, immunolocalization studies revealed that Cx43 gap junctions were prevalent at the cell surface of p.D3N expressing fibroblasts but greatly reduced in p.V216L expressing fibroblasts. Mutant expressing fibroblasts were further found to have reduced proliferation and migration capabilities. Finally, in response to TGFβ1, mutant expressing fibroblasts expressed significantly less alpha smooth muscle actin suggesting they were inefficient in their ability to differentiate into myofibroblasts. Collectively, our results suggest that ODDD patients may have subclinical defects in wound healing due to impaired function of dermal fibroblasts.
View details for DOI 10.1002/humu.21472
View details for Web of Science ID 000288464100018
View details for PubMedID 21305658
Nonsense Mutation-Associated Becker Muscular Dystrophy: Interplay Between Exon Definition and Splicing Regulatory Elements within the DMD Gene
2011; 32 (3): 299-308
Nonsense mutations are usually predicted to function as null alleles due to premature termination of protein translation. However, nonsense mutations in the DMD gene, encoding the dystrophin protein, have been associated with both the severe Duchenne Muscular Dystrophy (DMD) and milder Becker Muscular Dystrophy (BMD) phenotypes. In a large survey, we identified 243 unique nonsense mutations in the DMD gene, and for 210 of these we could establish definitive phenotypes. We analyzed the reading frame predicted by exons flanking those in which nonsense mutations were found, and present evidence that nonsense mutations resulting in BMD likely do so by inducing exon skipping, confirming that exonic point mutations affecting exon definition have played a significant role in determining phenotype. We present a new model based on the combination of exon definition and intronic splicing regulatory elements for the selective association of BMD nonsense mutations with a subset of DMD exons prone to mutation-induced exon skipping.
View details for DOI 10.1002/humu.21426
View details for Web of Science ID 000288034100007
View details for PubMedID 21972111
Clinical and genetic characterization of manifesting carriers of DMD mutations
2010; 20 (8): 499-504
Manifesting carriers of DMD gene mutations may present diagnostic challenges, particularly in the absence of a family history of dystrophinopathy. We review the clinical and genetic features in 15 manifesting carriers identified among 860 subjects within the United Dystrophinopathy Project, a large clinical dystrophinopathy cohort whose members undergo comprehensive DMD mutation analysis. We defined manifesting carriers as females with significant weakness, excluding those with only myalgias/cramps. DNA extracted from peripheral blood was used to study X-chromosome inactivation patterns. Among these manifesting carriers, age at symptom onset ranged from 2 to 47 years. Seven had no family history and eight had male relatives with Duchenne muscular dystrophy (DMD). Clinical severity among the manifesting carriers varied from a DMD-like progression to a very mild Becker muscular dystrophy-like phenotype. Eight had exonic deletions or duplications and six had point mutations. One patient had two mutations (an exonic deletion and a splice site mutation), consistent with a heterozygous compound state. The X-chromosome inactivation pattern was skewed toward non-random in four out of seven informative deletions or duplications but was random in all cases with nonsense mutations. We present the results of DMD mutation analysis in this manifesting carrier cohort, including the first example of a presumably compound heterozygous DMD mutation. Our results demonstrate that improved molecular diagnostic methods facilitate the identification of DMD mutations in manifesting carriers, and confirm the heterogeneity of mutational mechanisms as well as the wide spectrum of phenotypes.
View details for DOI 10.1016/j.nmd.2010.05.010
View details for Web of Science ID 000281347900003
View details for PubMedID 20630757
Identification of Uncommon Recurrent Potocki-Lupski Syndrome-Associated Duplications and the Distribution of Rearrangement Types and Mechanisms in PTLS
AMERICAN JOURNAL OF HUMAN GENETICS
2010; 86 (3): 462-470
Nonallelic homologous recombination (NAHR) can mediate recurrent rearrangements in the human genome and cause genomic disorders. Smith-Magenis syndrome (SMS) and Potocki-Lupski syndrome (PTLS) are genomic disorders associated with a 3.7 Mb deletion and its reciprocal duplication in 17p11.2, respectively. In addition to these common recurrent rearrangements, an uncommon recurrent 5 Mb SMS-associated deletion has been identified. However, its reciprocal duplication predicted by the NAHR mechanism had not been identified. Here we report the molecular assays on 74 subjects with PTLS-associated duplications, 35 of whom are newly investigated. By both oligonucleotide-based comparative genomic hybridization and recombination hot spot analyses, we identified two cases of the predicted 5 Mb uncommon recurrent PTLS-associated duplication. Interestingly, the crossovers occur in proximity to a recently delineated allelic homologous recombination (AHR) hot spot-associated sequence motif, further documenting the common hot spot features shared between NAHR and AHR. An additional eight subjects with nonrecurrent PTLS duplications were identified. The smallest region of overlap (SRO) for all of the 74 PTLS duplications examined is narrowed to a 125 kb interval containing only RAI1, a gene recently further implicated in autism. Sequence complexities consistent with DNA replication-based mechanisms were identified in four of eight (50%) newly identified nonrecurrent PTLS duplications. Our findings of the uncommon recurrent PTLS-associated duplication at a relative prevalence reflecting the de novo mutation rate and the distribution of 17p11.2 duplication types in PTLS reveal insights into both the contributions of new mutations and the different underlying mechanisms that generate genomic rearrangements causing genomic disorders.
View details for DOI 10.1016/j.ajhg.2010.02.001
View details for Web of Science ID 000275678800018
View details for PubMedID 20188345
Mutational Spectrum of DMD Mutations in Dystrophinopathy Patients: Application of Modern Diagnostic Techniques to a Large Cohort
2009; 30 (12): 1657-1666
Mutations in the DMD gene, encoding the dystrophin protein, are responsible for the dystrophinopathies Duchenne Muscular Dystrophy (DMD), Becker Muscular Dystrophy (BMD), and X-linked Dilated Cardiomyopathy (XLDC). Mutation analysis has traditionally been challenging, due to the large gene size (79 exons over 2.2 Mb of genomic DNA). We report a very large aggregate data set comprised of DMD mutations detected in samples from patients enrolled in the United Dystrophinopathy Project, a multicenter research consortium, and in referral samples submitted for mutation analysis with a diagnosis of dystrophinopathy. We report 1,111 mutations in the DMD gene, including 891 mutations with associated phenotypes. These results encompass 506 point mutations (including 294 nonsense mutations) and significantly expand the number of mutations associated with the dystrophinopathies, highlighting the utility of modern diagnostic techniques. Our data supports the uniform hypermutability of CGA>TGA mutations, establishes the frequency of polymorphic muscle (Dp427m) protein isoforms and reveals unique genomic haplotypes associated with "private" mutations. We note that 60% of these patients would be predicted to benefit from skipping of a single DMD exon using antisense oligonucleotide therapy, and 62% would be predicted to benefit from an inclusive multiexonskipping approach directed toward exons 45 through 55.
View details for DOI 10.1002/humu.21114
View details for Web of Science ID 000272796400007
View details for PubMedID 19937601
Paraneoplastic myopathy: response to intravenous immunoglobulin
2007; 17 (5): 404-408
Necrotizing myopathy is an unusual and severe form of paraneoplastic myopathy in which inflammation is minimal or absent. We report two cases of necrotizing myopathy which demonstrated significant response to intravenous immunoglobulin (IVIG) (one in spite of tumor progression). A third case represents the first association of anti-signal recognition particle (anti-SRP) syndrome with large-cell lung cancer. These cases highlight the role of histopathologic diagnosis in directing the treatment of paraneoplastic myopathy, and the role for IVIG in treatment of the syndrome.
View details for DOI 10.1016/j.nmd.2007.01.004
View details for Web of Science ID 000247041000007
View details for PubMedID 17336069
Inhibition of human surfactant protein a function by oxidation intermediates of nitrite
FREE RADICAL BIOLOGY AND MEDICINE
2002; 33 (12): 1703-1713
NitraNitration of protein tyrosine residues by peroxynitrite (ONOO - ) has been implicated in a variety of inflammatory diseases such as acute respiratory distress syndrome (ARDS). Pulmonary surfactant protein A (SP-A) has multiple functions including host defense. We report here that a mixture of hypochlorous acid (HOCl) and nitrite (NO 2 - ) induces nitration, oxidation, and chlorination of tyrosine residues in human SP-A and inhibits SP-A's ability to aggregate lipids and bind mannose. Nitration and oxidation of SP-A was not altered by the presence of lipids, suggesting that proteins are preferred targets in lipid-rich mixtures such as pulmonary surfactant. Moreover, both horseradish peroxidase and myeloperoxidase (MPO) can utilize NO 2 - and hydrogen peroxide (H 2 O 2 ) as substrates to catalyze tyrosine nitration in SP-A and inhibit its lipid aggregation function. SP-A nitration and oxidation by MPO is markedly enhanced in the presence of physiological concentrations of Cl - and the lipid aggregation function of SP-A is completely abolished. Collectively, our results suggest that MPO released by activated neutrophils during inflammation utilizes physiological or pathological levels of NO 2 - to nitrate proteins, and may provide an additional mechanism in addition to ONOO - formation, for tissue injury in ARDS and other inflammatory diseases associated with upregulated *NO and oxidant production.
View details for Web of Science ID 000179840700010
View details for PubMedID 12488138
Liposome-delivered superoxide dismutase prevents nitric oxide-dependent motor neuron death induced by trophic factor withdrawal
FREE RADICAL BIOLOGY AND MEDICINE
2000; 28 (3): 437-446
Inhibition of nitric oxide synthesis prevents rat embryonic motor neurons from undergoing apoptosis when initially cultured without brain-derived neurotrophic factor. Using an improved cell culture medium, we found that the partial withdrawal of trophic support even weeks after motor neurons had differentiated into a mature phenotype still induced apoptosis through a process dependent upon nitric oxide. However, nitric oxide itself was not directly toxic to motor neurons. To investigate whether intracellular superoxide contributed to nitric oxide-dependent apoptosis, we developed a novel method using pH-sensitive liposomes to deliver Cu, Zn superoxide dismutase intracellularly into motor neurons. Intracellular superoxide dismutase prevented motor neuron apoptosis from trophic factor withdrawal, whereas empty liposomes, inactivated superoxide dismutase in liposomes or extracellular superoxide dismutase did not. Neither hydrogen peroxide nor nitrite added separately or in combination affected motor neuron survival. Our results suggest that a partial reduction in trophic support induced motor neuron apoptosis by a process requiring the endogenous production of both nitric oxide and superoxide, irrespective of the extent of motor neuron maturation in culture.
View details for Web of Science ID 000085619000016
View details for PubMedID 10699756
Myeloperoxidase and horseradish peroxidase catalyze tyrosine nitration in proteins from nitrite and hydrogen peroxide
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
1998; 356 (2): 207-213
Nitration of tyrosine residues in proteins occurs in a wide range of inflammatory diseases involving neutrophil and macrophage activation. We report that both myeloperoxidase (MPO) and horseradish peroxidase (HRP) utilize nitrite (NO2-) and hydrogen peroxide (H2O2) as substrates to catalyze tyrosine nitration in proteins. MPO was approximately 10 times more effective than HRP as a nitration catalyst of bovine serum albumin (BSA). Nitration of BSA by MPO did not require chloride as a cofactor. Physiologic levels of chloride did not significantly inhibit nitration by MPO. Oxidation of chloride to hypochlorous acid (HOCl) is catalyzed by MPO but not by HRP, yet HRP also catalyzed nitration from hydrogen peroxide plus nitrite. Therefore, HOCl formation was not obligatory for tyrosine nitration. Although HOCl plus nitrite can nitrate the amino acid tyrosine in simple solutions, protein nitration by HOCl plus nitrite was not observed in heart homogenates, probably due to the presence of multiple alternative targets of both HOCl and HOCl plus nitrite. In contrast, MPO catalyzed nitration of many proteins in rat heart homogenates using NO2- plus H2O2, suggesting that peroxidase-catalyzed nitration of tyrosine could occur in the presence of competing substrates in vivo. HOCl could substitute for H2O2 as the oxidizing substrate for nitration of either BSA or tissue homogenates catalyzed by either peroxidase. Activated neutrophils may generate nitrotyrosine by several mechanisms, including peroxynitrite, HOCl plus nitrite, and a chloride-independent mechanism involving MPO, nitrite, and hydrogen peroxide.
View details for Web of Science ID 000075362000013
View details for PubMedID 9705211
DIFFERENTIAL MODULATION OF ASTROCYTE CYTOKINE GENE-EXPRESSION BY TGF-BETA
JOURNAL OF IMMUNOLOGY
1994; 153 (11): 5210-5221
In this study, we demonstrate that TGF-beta inhibits TNF-alpha expression, and induces/enhances IL-6 expression by primary rat astrocytes. Treatment of astrocytes with TGF-beta alone had no effect on TNF-alpha mRNA or protein expression; however, TGF-beta suppressed induction of TNF-alpha expression by three different stimuli (IFN-gamma/LPS, IFN-gamma/IL-1 beta, TNF-alpha) at both the protein and mRNA level. The extent of TGF-beta-mediated inhibition was greatest when astrocytes were pretreated with TGF-beta for 6 to 24 h, then exposed to the inducing stimuli. Inhibition of TNF-alpha mRNA steady-state levels by TGF-beta was a result of inhibition of TNF-alpha gene transcription, rather than degradation of the TNF-alpha message. In contrast, TGF-beta alone induced expression of IL-6 by astrocytes and synergized with two other cytokines, IL-1 beta and TNF-alpha, for enhanced IL-6 expression. TGF-beta-induced/enhanced IL-6 expression was mediated by transcriptional activation of the IL-6 gene. These results indicate that TGF-beta is an important regulator of cytokine production by astrocytes under inflammatory conditions in the brain.
View details for Web of Science ID A1994PT30100039
View details for PubMedID 7963576