[Molecular biology of mitochondrial DNA and mutations in mitochondrial cytopathy]

It has been clarified at the molecular and genetic levels that mitochondrial DNA (mt DNA) and/or nuclear DNA mutations are the cause of a group of diseases called mitochondrial cytopathies or mitochondrial myopathies. We review: (1) the characteristics of mtDNA and its inheritance, (2) the mtDNA deletions in Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia, (3) the point mutations in mtDNA tRNA(Leu(UUR)) gene at positions 3,243 and 3,271 in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), (4) the mtDNA deletions and point mutations in patients with dilated or hypertrophic cardiomyopathy, and (5) the mtDNA deletions or point mutation in three pedigrees with maternally transmitted non-insulin-dependent diabetes mellitus.