Mitochondrial Inheritance in a Mitochondrially Mediated Disease

Abstract

Mendelian inheritance involves the transmission to successive generations of DNA contained in genes in the nucleus, but DNA is also contained in mitochondria, where it is believed to be responsible for the encoding of certain mitochondrial enzymes. Since nearly all mitochondrial DNA is maternally transmitted, one might expect a nonmendelian pattern of inheritance in mitochondrial cytopathy, a syndrome in which there are abnormalities in mitochondrial structure and deficiencies in a variety of mitochondrial enzymes. We studied the pedigrees of 6 affected families whose members we had examined personally and of 24 families described in the literature. In 27 families, exclusively maternal transmission occurred; in 3 there was also paternal transmission in one generation. Altogether, 51 mothers but only 3 fathers had transmitted the condition.