Mitochondrial inheritance and heteroplasmy
Maternal inheritance of mtDNA, heteroplasmy, the threshold effect and the bottleneck, the classic syndromes (MELAS, MERRF, LHON, Leigh), drug hazards and Australian mitochondrial donation.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Each cell holds hundreds to thousands of copies of a 16.6 kb circular mtDNA encoding 13 respiratory chain proteins, 22 tRNAs and 2 rRNAs. The other ~1,500 mitochondrial proteins are nuclear-encoded.
- mtDNA is inherited only from the mother. Affected men never transmit; affected women transmit mtDNA to all children; with a heteroplasmic variant the mutant load each child receives varies, from none detectable to high.
- Heteroplasmy and the threshold effect explain why relatives with the same variant look so different.
Loading the rest of the note…
Finished reading?
Sources
- GeneReviews: Primary Mitochondrial Disorders OverviewUniversity of Washington, Seattle (NCBI Bookshelf NBK1224)
- McDermott JH et al. Clinical Pharmacogenetics Implementation Consortium guideline for the use of aminoglycosides based on MT-RNR1 genotype. Clin Pharmacol Ther 2022;111:366-72Clinical Pharmacology & Therapeutics, 2022
- Gorman GS et al. Prevalence of nuclear and mitochondrial DNA mutations related to adult mitochondrial disease. Ann Neurol 2015;77:753-9Annals of Neurology, 2015
- Mitochondrial Donation Law Reform (Maeve's Law) Act 2022AU/NZAustralian Government, Federal Register of Legislation, 2022
- mitoHOPE program: news and progressAU/NZMonash University, 2025
- McFarland R et al. Mitochondrial donation in a reproductive care pathway for mtDNA disease. N Engl J Med 2025;393:461-8New England Journal of Medicine, 2025
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback