Familial myopathy with elevated serum angiotensin-converting enzyme, creatine kinase and lactate dehydrogenase isoenzyme 5.

A family is reported in which two members presented with proximal myopathy associated with high serum levels of angiotensin-converting enzyme (SACE), creatine kinase (CK), and lactate dehydrogenase isoenzyme 5. Examination of three relatives revealed elevated SACE levels in all of them, but no myopathy. No evidence of sarcoidosis, the most common disease associated with high SACE levels, could be found. Muscle biopsies of the two affected men revealed myopathic features without granuloma formation. Extensive biochemical, metabolic, immunological, and microbiological studies were all non-contributory. Corticosteroid and, in one patient, azathioprine treatment resulted in an improvement of muscle weakness and in a decrease of SACE as well as CK levels.