Early diagnosis and treatment of homocystinuria.

Homocystinuria was diagnosed in a newborn infant by detection of homocystine in urine on the fourth day of life, and by the demonstration of a marked elevation of serum methionine concentration on the fifth day. Treatment with a special low-methionine diet has reduced the concentrations of methionine in blood to near-normal levels. This metabolic disease should be searched for by routine screening of newborn infants, and may possibly respond favorably to dietary therapy.