Carmel Grace McCullough
MD Student with Scholarly Concentration in Molecular Basis of Medicine, expected graduation Spring 2025
Masters Student in Medicine, admitted Summer 2024
Education & Certifications
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Bachelor of Science, University of Southern California, Neuroscience (2019)
All Publications
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Common mitochondrial deletions in RNA-Seq: evaluation of bulk, single-cell, and spatial transcriptomic datasets
COMMUNICATIONS BIOLOGY
2024; 7 (1): 200
Abstract
Common mitochondrial DNA (mtDNA) deletions are large structural variants in the mitochondrial genome that accumulate in metabolically active tissues with age and have been investigated in various diseases. We applied the Splice-Break2 pipeline (designed for high-throughput quantification of mtDNA deletions) to human RNA-Seq datasets and describe the methodological considerations for evaluating common deletions in bulk, single-cell, and spatial transcriptomics datasets. A robust evaluation of 1570 samples from 14 RNA-Seq studies showed: (i) the abundance of some common deletions detected in PCR-amplified mtDNA correlates with levels observed in RNA-Seq data; (ii) RNA-Seq library preparation method has a strong effect on deletion detection; (iii) deletions had a significant, positive correlation with age in brain and muscle; (iv) deletions were enriched in cortical grey matter, specifically in layers 3 and 5; and (v) brain regions with dopaminergic neurons (i.e., substantia nigra, ventral tegmental area, and caudate nucleus) had remarkable enrichment of common mtDNA deletions.
View details for DOI 10.1038/s42003-024-05877-4
View details for Web of Science ID 001163774500004
View details for PubMedID 38368460
View details for PubMedCentralID PMC10874445
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Utilizing RNA and outlier analysis to identify an intronic splice-altering variant in AP4S1 in a sibling pair with progressive spastic paraplegia
HUMAN MUTATION
2020; 41 (2): 412-419
Abstract
We report a likely pathogenic splice-altering AP4S1 intronic variant in two sisters with progressive spastic paraplegia, global developmental delay, shy character, and foot deformities. Sequencing was completed on whole-blood messenger RNA (mRNA) and analyzed for gene expression outliers after exome sequencing analysis failed to identify a causative variant. AP4S1 was identified as an outlier and contained a rare homozygous variant located three bases upstream of exon 5 (NC_000014.8(NM_007077.4):c.295-3C>A). Confirmed by additional RNA-seq, reverse-transcription polymerase chain reaction, and Sanger sequencing, this variant corresponded with exon 5, including skipping, altered isoform usage, and loss of expression from the canonical isoform 2 (NM_001128126.3). Previously, loss-of-function variants within AP4S1 were associated with a quadriplegic cerebral palsy-6 phenotype, AP-4 Deficiency Syndrome. In this study, the inclusion of mRNA-seq allowed for the identification of a previously missed splice-altering variant, and thereby expands the mutational spectrum of AP-4 Deficiency Syndrome to include impacts to some tissue-dependent isoforms.
View details for DOI 10.1002/humu.23939
View details for Web of Science ID 000496346400001
View details for PubMedID 31660686