skip to main content

Mitochondrial Myopathy – Genetics — SCE Neurology MCQ

Instant feedback + full explanation. One question, done properly.

HardNeurogeneticsMitochondrial Myopathy – GeneticsSCE Neurology

A patient has chronic progressive external ophthalmoplegia, proximal myopathy and ragged-red fibres. Blood testing is unrevealing. Which molecular strategy is most appropriate next?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Analyse mitochondrial DNA in an informative tissue such as muscle for deletions and sequence variants

The best answer is “Analyse mitochondrial DNA in an informative tissue such as muscle for deletions and sequence variants”. Heteroplasmic mtDNA variants or deletions may be missed in blood, so muscle can be the most informative tissue; nuclear causes also need consideration. “Stop genetic evaluation because a negative blood test excludes mitochondrial disease” can be reasonable in another presentation, but it does not account for the defining feature here. “Test only for DMPK repeat expansion” can be reasonable in another presentation, but it does not account for the defining feature here. “Use chromosome microarray as the definitive mitochondrial test” can be reasonable in another presentation, but it does not account for the defining feature here. “Test BRCA1 and BRCA2 because ophthalmoplegia is neoplastic” can be reasonable in another presentation, but it does not account for the defining feature here.

Reference: GeneReviews: Primary mitochondrial disorders overview: https://www.ncbi.nlm.nih.gov/books/NBK1224/