[Mitochondrial medicine for internists].

Human mitochondrial DNA (mtDNA) is a small, circular molecule, encoding for the translational machinery of the mitochondrion, as well as for 13 structural proteins that are all subunits of the respiratory chain. Point mutations, deletions, and copy-number variations are now functionally and genetically linked to human disease. Despite the fact that mtDNA is solely transmitted from the mother to the offspring, e.g. is maternally inherited, some mutations may occur spontaneously or may be acquired due to defects in nuclear DNA, e.g. are inherited in a mendelian fashion. The internist encounters predominantly myopathies, cardiomyopathies, lactic acidosis or diabetes mellitus but mtDNA-changes are also present with neurologic, hematologic and renal symptoms. Acquired mtDNA alterations are responsible for important drug side effects, such as ifosfamide, carboplatin, doxorubicin or nucleoside-analog reverse-transcriptase inhibitors. A specific mtDNA point-mutation predisposes to aminoglycoside-induced sensorineural deafness.