Mitochondrial Myopathy – Genetic Testing — SCE Neurology MCQ
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Correct answer: C — Mitochondrial-DNA sequencing with deletion analysis
The best answer is “Mitochondrial-DNA sequencing with deletion analysis”. The phenotype is a mitochondrial myopathy such as CPEO; mtDNA point variants and large-scale deletions should be assessed, and blood may miss heteroplasmic or deletion disease so muscle or another informative tissue can be required. “BRCA1 and BRCA2 hereditary-cancer gene testing” is less appropriate because BRCA testing addresses hereditary cancer susceptibility “HTT CAG-repeat analysis for Huntington disease” is less appropriate because HTT expansion causes Huntington disease “Chromosomal microarray for copy-number variant detection” is less appropriate because microarray does not reliably detect heteroplasmic mtDNA variants or common deletion patterns “NOTCH3 sequencing for hereditary small-vessel disease” is less appropriate because NOTCH3 variants cause CADASIL rather than ophthalmoplegic myopathy
Reference: GeneReviews: Primary Mitochondrial Disorders Overview. https://www.ncbi.nlm.nih.gov/books/NBK1224/