mtDNA variants

mtDNA

Mitochondria carry their own circular genome of about 16,500 bases. Variants in it can cause energy-metabolism disorders, often involving muscle and the nervous system. Genome checks the mitochondrial sequence for known and novel variants.

Heteroplasmy and threshold

Each cell contains hundreds to thousands of mtDNA copies. A pathogenic variant must reach a sufficiently high fraction before energy production visibly suffers. The fraction can vary between tissues, so a blood finding does not represent all organs.

How Genome analyses

Genome calls mtDNA variants from the reads and pairs them with the mitochondrial disease context, for example MITOMAP entries. The report separates the technical variant review from interpretation and avoids diagnostic overclaims.

What Genome measures. Mitochondrial DNA variants against the reference (rCRS), with heteroplasmy fraction where coverage allows, and a match against the mitochondrial disease context.

Related topics

mtDNA haplogroups

Sources

  1. 1Gorman et al., 2016 Mitochondrial diseases. Nature Reviews Disease Primers 2:16080. doi.org/10.1038/nrdp.2016.80
  2. 2Lott et al., 2013 mtDNA variation and analysis using MITOMAP and MITOMASTER. Current Protocols in Bioinformatics 44:1.23.1–1.23.26. doi.org/10.1002/0471250953.bi0123s44
  3. 3Stewart & Chinnery, 2015 The dynamics of mitochondrial DNA heteroplasmy: implications for human health and disease. Nature Reviews Genetics 16:530–542. doi.org/10.1038/nrg3966