Familial elevation of serum angiotensin converting enzyme.

We report here a familial clustering of elevated serum angiotensin converting enzyme (ACE) levels. The patient is a 58-year-old Japanese female who had been in excellent health until age 45 when she developed an occlusion of the left central retinal vein. She was otherwise in excellent health, and no laboratory abnormality except a marked elevation of serum ACE level (625 nmol/min/ml; normal range; 22-40 nmol/min/ml of serum) was found. Her blood pressure was within normal limits (140/80 mmHg). There was no evidence for the diagnosis of sarcoidosis, Gaucher's disease, leprosy, hyperthyroidism, diabetic retinopathy, or liver disease. One of her two sisters also showed a marked increase in serum ACE activity (303 nmol/min/ml), and remarkably high levels of serum ACE (276 and 294 nmol/min/ml) were demonstrated in both sons of this sister. All the members of this family have been in excellent health. The serum ACE activity was activated by chloride and cobalt ions, and inhibited by EDTA, captopril and rabbit antiserum to purified human plasma ACE. Thus our study showed a familial clustering of elevated serum ACE in individuals who did not have conventional disease patterns associated with elevated serum ACE.