Leigh disease caused by the mitochondrial DNA G14459A mutation in unrelated families

Leigh disease can be caused by defects of both nuclear and mitochondrially encoded genes. One mitochondrial DNA mutation, G14459A, has been associated with both respiratory chain complex I deficiency and Leber's hereditary op tic neuropathy, with or without dystonia. Here, we report the occurrence of this mutation in 3 complex I-deficient patients from 2 separate pedigrees who presented with Leigh disease, with no evidence or family history of Leb er's hereditary optic neuropathy or dystonia.