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Mitochondrial inheritance – LHON — RACP Paediatrics MCQ

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ModerateGeneticsMitochondrial inheritance – LHONRACP Paediatrics

A family has Leber hereditary optic neuropathy (LHON, m.11778G>A mitochondrial DNA mutation). The affected mother asks about risk to her children. What is the inheritance pattern?

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Correct answer: C — Mitochondrial – maternal

LHON is caused by mitochondrial DNA mutations and follows maternal inheritance. All children of an affected mother will inherit the mutation (mitochondria are exclusively maternally inherited). However, penetrance is variable – only ~50% of males and ~10-15% of females with the mutation develop visual loss. An affected father CANNOT pass mtDNA mutations to any children.

Reference: RACP Paediatric Curriculum – Genetics; RCH Melbourne – 2023