The search for disorders of metabolism among the mentally retarded is tedious and not infrequently appears to be unrewarding, yet on a number of occasions it has yielded discoveries which have illuminated knowledge of normal metabolism and have led to new methods for the prevention and treatment of disease. The following two papers describe such an event.
In 1961, Drs. Mary Efron and Emily Bixby began a metabolic screening program of the 2,000 patients at the Wrentham State School. As part of this, in order to assess the frequency of homocystinuria, they performed the cyanide-nitroprusside test on urine samples of all the patients. Five tests were positive. In four instances, the results were due to cystinuria; no patients with homocystinuria were discovered. However, the fifth patient proved to be of even greater interest since here the positive nitroprusside reaction was due to a new sulfur-containing amino acid which, as it