Genetic disorder related to mitochondrial DNA
transmission (i.e., exclusively from mother to child, either male or
female). At least four mutations in mitochondrial DNA (including G11778A,
T14484C, and G3460A) are associated with this clinical abnormality.
Different family pedigrees show different mutations but with clinically
similar pictures. The pattern of transmission within a kindred are not in
accordance with mendelian principles, and it is apparent that a complex
mechanism of inheritance is in operation. The disease is never transmitted
by affected men; it is transmitted by affected women or, most frequently, by
female carriers of the gene.