- Clinical Genetics
Honors & Awards
Pfizer/ACMGF Next Generation Clinical Laboratory Biochemical Genetics Fellowship Award, American College of Medical Genetics (2021)
Henry Christian Award, American Federation for Medical Research (AFMR) (2020)
Outstanding Recent Biochemistry Undergraduate Alumni Award, Virginia Tech (2018)
J. Edmund and Kathryn S. Bradley Award for Excellence in Pediatrics, University of Maryland School of Medicine (2018)
Commencement Speaker for Epidemiology and Human Genetics Graduate Program, University of Maryland School of Medicine (2016)
2016 PhD Thesis of the Year Award, Graduate Program in Life Sciences, University of Maryland School of Medicine (2016)
Short Bones, Renal Stones, and Diagnostic Moans: Hypercalcemia in a Girl Found to Have Coffin-Lowry Syndrome.
Journal of investigative medicine high impact case reports
2022; 10: 23247096221101844
Pathogenic variants in RPS6KA3 are associated with Coffin-Lowry syndrome (CLS), an X-linked semidominant disorder characterized by intellectual disability, stimulus-induced drop attacks, distinctive facial features, progressive kyphoscoliosis, and digit anomalies in hemizygous males. Heterozygous females may also have features of CLS; however, there can be considerable phenotypic variation, often attributed to ratios of X-inactivation in various tissue types. Although skeletal anomalies and short stature are hallmarks of CLS, hypercalcemia has not been reported. Here we describe a 30-month-old girl with gross motor delays, short stature, dysmorphic features, bilateral duplicated renal collecting systems, and no family history of hypercalcemia who required multiple admissions for idiopathic hypercalcemia necessitating bisphosphonate infusions at 12.5 and 15 months of age. A maternally inherited likely-pathogenic variant in RPS6KA3 was identified by trio exome sequencing, consistent with the diagnosis of CLS in the proband and her mother. Maternal history was notable only for decreased height compared to first-degree relatives, bilateral genu valgum, and a bicornuate uterus; she was later found to also have a partially duplicated left renal collecting system. Subsequent X-inactivation studies in blood aligned with the phenotypic variation between mother and daughter. Although hypercalcemia is not a reported feature in CLS, there is evidence of interrupted osteoblast differentiation, providing a potential mechanism for hypercalcemia in this genetic condition. The hypercalcemia in this case may represent a severe presentation of an unrecognized clinical feature in CLS that resolves with age. This case further highlights the intrafamilial phenotypic variation of CLS among females, suggesting X-inactivation as the underlying mechanism, and demonstrates the value of exome sequencing in patients for whom a genetic disorder is highly suspected but not identified despite thorough evaluation.
View details for DOI 10.1177/23247096221101844
View details for PubMedID 35638718
MITOCHONDRIAL-ATP6-ASSOCIATED DISEASE PRESENTS WITH DISTINCT PATTERN ON NEWBORN SCREENING: SHOULD IT BE INCLUDED AS A SECONDARY CONDITION?
ACADEMIC PRESS INC ELSEVIER SCIENCE. 2022: 247-248
View details for Web of Science ID 000772339900011
SUCCESSFUL CARDIAC TRANSPLANTATION AND LONG-TERM FOLLOW-UP IN DNAJC19-ASSOCIATED DILATED CARDIOMYOPATHY WITH ATAXIA
ACADEMIC PRESS INC ELSEVIER SCIENCE. 2022: 302
View details for Web of Science ID 000772339900104
- Biochem for the Win! The added value of biochemical genetic testing for diagnosis and variant interpretation in the genomic era ELSEVIER SCIENCE INC. 2022: S24
- Medical genetics training in the COVID-19 era: A resident's perspective. American journal of medical genetics. Part A 2021
Profound neonatal lactic acidosis and renal tubulopathy in a patient with glycogen storage disease type IXɑ2 secondary to a de novo pathogenic variant in PHKA2.
Molecular genetics and metabolism reports
2021; 27: 100765
The phenotype of individuals with glycogen storage disease (GSD) IX appears to be highly variable, even within subtypes. Features include short stature, fasting hypoglycemia with ketosis, hepatomegaly, and transaminitis. GSD IXɑ2 is caused by hemizygous pathogenic variants in PHKA2, and results in deficiency of the phosphorylase kinase enzyme, particularly in the liver. Like other GSDs, GSD IXɑ2 can present with hypoglycemia and post-prandial lactic acidosis, but has never been reported in a newborn, nor with lactic acidosis as the presenting feature. Here we describe the clinical presentation and course of a newborn boy with profound neonatal lactic and metabolic acidosis, renal tubulopathy, and sensorineural hearing loss (SNHL) diagnosed with GSD IXɑ2 through exome sequencing. Review of the literature suggests this case represents an atypical and severe presentation of GSD IXɑ2 and proposes expansion of the phenotype to include neonatal lactic acidosis and renal tubulopathy.
View details for DOI 10.1016/j.ymgmr.2021.100765
View details for PubMedID 34277355
View details for PubMedCentralID PMC8261893
Unexpected diagnoses in patients with abnormal newborn screening
ACADEMIC PRESS INC ELSEVIER SCIENCE. 2021: S354
View details for Web of Science ID 000639219800534
Aicardi-Goutières syndrome may present with positive newborn screen for X-linked adrenoleukodystrophy.
American journal of medical genetics. Part A
We report three unrelated probands, two male and one female, diagnosed with Aicardi-Goutières syndrome (AGS) after screening positive on California newborn screening (CA NBS) for X-linked adrenoleukodystrophy (X-ALD) due to elevated C26:0 lysophosphatidylcholine (C26:0-LPC). Follow-up evaluation was notable for elevated C26:0, C26:1, and C26:0/C22:0 ratio, and normal red blood cell plasmalogens levels in all three probands. Diagnoses were confirmed by molecular sequencing prior to 12 months of age after clinical evaluation was inconsistent with X-ALD or suggestive of AGS. For at least one proband, the early diagnosis of AGS enabled candidacy for enrollment into a therapeutic clinical trial. This report demonstrates the importance of including AGS on the differential diagnosis for individuals who screen positive for X-ALD, particularly infants with abnormal neurological features, as this age of onset would be highly unusual for X-ALD. While AGS is not included on the Recommended Universal Screening Panel, affected individuals can be identified early through state NBS programs so long as providers are aware of a broader differential that includes AGS. This report is timely, as state NBS algorithms for X-ALD are actively being established, implemented, and refined.
View details for DOI 10.1002/ajmg.a.62160
View details for PubMedID 33683010
Genetics of recurrent pregnancy loss: a review.
Current opinion in obstetrics & gynecology
Human reproduction is remarkably inefficient; with pregnancy loss occurring in 10-30% of clinically recognized pregnancies. Of those, 3-5% of couples experience recurrent pregnancy loss (RPL), more than 50% of who never receive an underlying diagnosis. Herein, we review evidence that genetic changes, including pathogenic variant(s) in highly penetrant genes, may provide an explanation for a proportion of couples with pregnancy loss.Genetic abnormalities that may predispose to pregnancy loss include chromosomal aneuploidy, copy number variants, single-gene changes and others. Although previously limited by the need for hypothesis-driven assessment, advancement of various molecular technologies have sheparded in the opportunity to identify molecular cause of highly heterogeneous conditions, including RPL. The identification of causative genetic aberrations associated with RPL demonstrates a promising area of further research.The journey of human development from a single-cell zygote to a term infant is complex process. Early research into copy number variants and highly penetrant single-gene changes may provide diagnosis for a proportion of couples with RPL as well as inform genes critical for early human development.
View details for DOI 10.1097/GCO.0000000000000695
View details for PubMedID 33605623
- Case 1: Rapidly Rising Bilirubin Level in a 3-day-old Term Infant. NeoReviews 2020; 21 (10): e687–e690
nonsense variants on DHEA homeostasis.
Molecular genetics and metabolism reports
2017; 10: 84-91
Sulfate is critical in the biotransformation of multiple compounds via sulfation. These compounds include neurotransmitters, proteoglycans, xenobiotics, and hormones such as dehydroepiandrosterone (DHEA). Sulfation reactions are thought to be rate-limited by endogenous sulfate concentrations. The gene, SLC13A1, encodes the sodium-sulfate cotransporter NaS1, responsible for sulfate (re)absorption in the intestines and kidneys. We previously reported two rare, non-linked, nonsense variants in SLC13A1 (R12X and W48X) associated with hyposulfatemia (P = 9 × 10- 20).To examine the effect of serum sulfate concentration and sulfate-lowering genotype on DHEA homeostasis.Retrospective cohort study.Academic research.Participants of the Amish Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study and the Amish Hereditary and Phenotype Intervention (HAPI) Study.DHEA, DHEA-S, and DHEA-S/DHEA ratio.Increased serum sulfate was associated with decreased DHEA-S (P = 0.03) and DHEA-S/DHEA ratio (P = 0.06) in males but not females. Female SLC13A1 nonsense variant carriers, who had lower serum sulfate (P = 9 × 10- 13 ), exhibited 14% lower DHEA levels (P = 0.01) and 7% higher DHEA-S/DHEA ratios compared to female non-carriers (P = 0.002). Consistent with this finding, female SLC13A1 nonsense variant carriers also had lower total testosterone levels compared to non-carrier females (P = 0.03).Our results demonstrate an inverse relationship between serum sulfate, and DHEA-S and DHEA-S/DHEA ratio in men, while also suggesting that the sulfate-lowering variants, SLC13A1 R12X and W48X, decrease DHEA and testosterone levels, and increase DHEA-S/DHEA ratio in women. While paradoxical, these results illustrate the complexity of the mechanisms involved in DHEA homeostasis and warrant additional studies to better understand sulfate's role in hormone physiology.
View details for DOI 10.1016/j.ymgmr.2017.01.005
View details for PubMedID 28154797
View details for PubMedCentralID PMC5278115
- Are Patients with Psychogenic Movement Disorders More Likely to be Healthcare Workers? MOVEMENT DISORDERS CLINICAL PRACTICE 2017; 4 (1): 62–67
From Genotype to Phenotype: Nonsense Variants in SLC13A1 Are Associated with Decreased Serum Sulfate and Increased Serum Aminotransferases
G3-GENES GENOMES GENETICS
2016; 6 (9): 2909-2918
Using genomic applications to glean insights into human biology, we systematically searched for nonsense single nucleotide variants (SNVs) that are rare in the general population but enriched in the Old Order Amish (Amish) due to founder effect. We identified two nonlinked, nonsense SNVs (R12X and W48X) in SLC13A1 (allele frequencies 0.29% and 0.74% in the Amish; enriched 1.2-fold and 3.7-fold, compared to the outbred Caucasian population, respectively). SLC13A1 encodes the apical sodium-sulfate cotransporter (NaS1) responsible for sulfate (re)absorption in the kidneys and intestine. SLC13A1 R12X and W48X were independently associated with a 27.6% (P = 2.7 × 10(-8)) and 27.3% (P = 6.9 × 10(-14)) decrease in serum sulfate, respectively (P = 8.8 × 10(-20) for carriers of either SLC13A1 nonsense SNV). We further performed the first exome- and genome-wide association study (ExWAS/GWAS) of serum sulfate and identified a missense variant (L348P) in SLC26A1, which encodes the basolateral sulfate-anion transporter (Sat1), that was associated with decreased serum sulfate (P = 4.4 × 10(-12)). Consistent with sulfate's role in xenobiotic detoxification and protection against acetaminophen-induced hepatotoxicity, SLC13A1 nonsense SNV carriers had higher aminotransferase levels compared to noncarriers. Furthermore, SLC26A1 L348P was associated with lower whole-body bone mineral density (BMD) and higher serum calcium, consistent with the osteochondrodysplasia exhibited by dogs and sheep with naturally occurring, homozygous, loss-of-function mutations in Slc13a1 This study demonstrates the power and translational potential of systematic identification and characterization of rare, loss-of-function variants and warrants additional studies to better understand the importance of sulfate in human physiology, disease, and drug toxicity.
View details for DOI 10.1534/g3.116.032979
View details for Web of Science ID 000384021400022
View details for PubMedID 27412988
View details for PubMedCentralID PMC5015947
Educational Innovations in Clinical Pharmacogenomics
CLINICAL PHARMACOLOGY & THERAPEUTICS
2016; 99 (6): 582-584
Genetic and genomic discovery is revolutionizing medicine at an extraordinary pace, leading to a better understanding of disease and improved treatments for patients. This advanced pace of discovery presents an urgency to expand medical school curricula to include genetic and genomic testing (including pharmacogenomics), and integration of genomic medicine into clinical practice. Consequently, organizations and healthcare authorities have charged medical schools with training future physicians to be competent in their knowledge of genomic implementation.
View details for DOI 10.1002/cpt.352
View details for Web of Science ID 000376246600016
View details for PubMedID 26875057
Pharmacometabolomics reveals that serotonin is implicated in aspirin response variability.
CPT: pharmacometrics & systems pharmacology
While aspirin is generally effective for prevention of cardiovascular disease, considerable variation in drug response exists, resulting in some individuals displaying high on-treatment platelet reactivity. We used pharmacometabolomics to define pathways implicated in variation of response to treatment. We profiled serum samples from healthy subjects pre- and postaspirin (14 days, 81 mg/day) using mass spectrometry. We established a strong signature of aspirin exposure independent of response (15/34 metabolites changed). In our discovery (N = 80) and replication (N = 125) cohorts, higher serotonin levels pre- and postaspirin correlated with high, postaspirin, collagen-induced platelet aggregation. In a third cohort, platelets from subjects with the highest levels of serotonin preaspirin retained higher reactivity after incubation with aspirin than platelets from subjects with the lowest serotonin levels preaspirin (72 ± 8 vs. 61 ± 11%, P = 0.02, N = 20). Finally, ex vivo, serotonin strongly increased platelet reactivity after platelet incubation with aspirin (+20%, P = 4.9 × 10(-4), N = 12). These results suggest that serotonin is implicated in aspirin response variability.
View details for DOI 10.1038/psp.2014.22
View details for PubMedID 25029353
View details for PubMedCentralID PMC4120016
Pharmacogenomics of Anti-platelet and Anti-coagulation Therapy
CURRENT CARDIOLOGY REPORTS
2013; 15 (7)
Arterial thrombosis is a major component of vascular disease, especially myocardial infarction (MI) and stroke. Current anti-thrombotic therapies such as warfarin and clopidogrel are effective in inhibiting cardiovascular events; however, there is great inter-individual variability in response to these medications. In recent years, it has been recognized that genetic factors play a significant role in drug response, and, subsequently, common variants in genes responsible for metabolism and drug action have been identified. These discoveries along with new diagnostic targets and therapeutic strategies hold promise for more effective individualized anti-coagulation and anti-platelet therapy.
View details for DOI 10.1007/s11886-013-0381-3
View details for Web of Science ID 000345083100009
View details for PubMedID 23797323
View details for PubMedCentralID PMC3809070
Pharmacogenomics of anti-platelet therapy: how much evidence is enough for clinical implementation?
JOURNAL OF HUMAN GENETICS
2013; 58 (6): 339-345
Pharmacogenomics, the study of the genomics of drug response and adverse effects, holds great promise for more effective individualized (personalized) medicine. Recent evidence supports a role of loss-of-function (LOF) variants in the cytochrome P450 enzyme CYP2C19 as a determinant of clopidogrel response. Patients given clopidogrel after percutaneous coronary intervention who carry LOF variants do not metabolize clopidogrel, a prodrug, into its active form resulting in decreased inhibition of platelet function and a higher likelihood of recurrent cardiovascular events. Despite a large body of evidence supporting clinical utility, adoption of anti-platelet pharmacogenetics into clinical practice has been slow. In this review, we summarize the pharmacokinetic, pharmacodynamic and clinical evidence, identify gaps in knowledge and other barriers that appear to be slowing adoption, and describe CYP2C19 pharmacogenetics implementation projects currently underway. Only when we surmount these barriers will clinicians be able to use pharmacogenetic information in conjunction with the history, physical examination and other medical tests and information to choose the most efficacious anti-platelet therapy for each individual patient.
View details for DOI 10.1038/jhg.2013.41
View details for Web of Science ID 000320843600007
View details for PubMedID 23697979
View details for PubMedCentralID PMC3715315