Mitochondrial inheritance

- maternal in origin
- both sexes can be affected

Examples
- Leber's optic atrophy
- MELAS (mitochondrial encephalopathy + lactic acidosis + stroke)
- MERRF (myoclonic epilepsy with ragged red fibre)
- Kearns-Sayre syndrome (oculocraniosomatic disease)
- progressive external ophthalmoplegia
- Pearson syndrome (lactic acidosis + pancreatic insufficiency + pancytopenia)
- some deafness
- some familial diabetes mellitus