Autosomal dominant Kearns-Sayre syndrome.

External ophthalmoplegia, retinal pigmentary degeneration, and heart block constitute the Kearns-Sayre syndrome. Skeletal muscle weakness, deafness, ataxia and endocrine disturbances also may occur. We examined 15 members in two generations of a family with autosomal dominant Kearns-Sayre syndrome. Seven had external ophthalmoplegia, six had electrocardiographic abnormalities, six had limb weakness nad six patients were normal. A deltoid muscle biopsy specimen from one patient contained typical "ragged-red fibers," abnormal lipid accumulation, and mitochondria increased in size and number, containing inclusions. The study demonstrated: (1) the marked variability in genetic expression; (2) the need to examine family members to discover asymptomatic patients and to establish an otherwise unrecognized hereditary pattern; and (3) the absence of specific and consistent biochemical abnormalities.