[2 familial cases of homocystinuria one of which revealed by fatal hypertensive encephalopathy].

Two cases in the same sibship are reported. The elder patient, who had posterior dislocation of the lens resulting in glaucoma and significant psychomotor retardation, died at the age of 13 with malignant arterial hypertension. Death was caused by thrombotic events (left carotid artery, coronary vessels, renal arteries and arterioles with fibrous endarteritis). The sister, aged 10, had psychomotor retardation and anomalies of both lenses. Chromatographic studies of serum and urine amino acids confirmed the diagnosis of homocystinuria. The form was pyridoxine-sensitive as shown by the results of therapy with pyridoxine and folates. We suggest that homocystinuria, although infrequent, should be routinely looked for in every child with a thrombotic event since a pyridoxine-folate combination is successful in half the cases, preventing the development of complications especially when initiated early.