[Homocystinuria: effectiveness of the treatment with pyridoxine, folic acid, and betaine].

We present the results achieved with vitamin (pyridoxine and folic acid) and betaine (trimethyl-glycine) treatment of three patients with homocystinuria. Cases 1 and 2 were detected by having clinical findings suggestive of the disease (ocular and orthopedic alterations) and case 3 was diagnosed after a family metabolic screening was done. All presented a positive Brand's test and an abnormal elevation of plasma and urine homocysteine, as well as high methionine and low cystine levels in the plasma. Initially, when pyridoxine (600 mg/d) and folic acid (10 mg/d) were given for one month, a partial fall in the homocysteine levels was observed in cases 2 and 3, but not in case 1. When betaine was added (6 g/d), homocysteine disappeared from the plasma after the first month in cases 2 and 3, but only after the third month in case 1. Case 1 also showed a moderate clinical improvement in behavior and school performance. The treatment was maintained for two years in case 1, and for one year in cases 2 and 3. After betaine therapy, no disturbances were observed in the hepatic, renal and bone marrow functions, nor were there any clinically relevant ill-effects. These findings show that betaine offers a therapeutic alternative in the treatment of this disease, independent of the patient's response to pyridoxine.