Familial mitochondrial myopathy with cataract.

A 62-year-old female had severe progressive ophthalmoplegia associated with facial, pharyngeal and limb muscle involvement. When 40, she had undergone surgery for bilateral cataract present for about 20 years. Biopsies of skeletal muscles indicated myopathy; histochemistry and electron microscopy gave evidence of abnormal mitochondria in type I fibres. Bilateral cataract needing surgical treatment at 32 was the prominent symptom in her daughter, then with only mild facial weakness. Despite absence of ophthalmoplegia, similar pathological changes were observed in an inferior oblique muscle. The child of the former, a 10-year-old clinically healthy boy, had been surgically treated for a bilateral cataract at the age of 3. As indicated by a review of literature, cataract is not an exceptional occurrence in this particular type of ocular myopathy and therefore should be included within its multisystem associations. The same HLA haplotype (A2-B21) was found in the three patients.