Pyridoxine-Unresponsive Homocystinuria

HOMOCYSTINURIA due to cystathionine synthase deficiency was recognized as an entity in 1962.1 , 2 It is characterized by dislocation of the lenses, mental retardation, skeletal abnormalities and thromboembolic phenomena. Patients may have some or all of the symptoms and signs. Vascular accident is a frequent cause of death. Methionine, the precursor of homocystine, is also present in increased amounts in the blood and urine; it is formed by the remethylation of homocysteine. Attempts to lower the accumulation of methionine and homocysteine in the body by restriction of methionine intake and high doses of pyridoxine, a cofactor for cystathionine synthase, have been . . .