Heterogeneous phenotypes of mitochondrial encephalomyopathy in a single kindred

Five patients with mitochondrial disorders in a single family showed marked heterogeneity of clinical signs and symptoms. Two patients had the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes; one had blepharoptosis, seizures, and diabetes insipidus; and two had a nonspecific encephalomyopathic disorder. This family supports the concept of a "mitochondrial cytopathy."