Abstract
Results of a urine and blood screening study of 2 groups of profoundly, severely, and moderately retarded patients (except for mongoloids) in Finland are reported. The 1st group consisted of a statistically selected sample and the 2nd group of institutionalized patients taken at random. The most important finding was the very low prevalence of phenylketonuria (0.096%) for the mentally retarded population. The corresponding figures for 5 other abnormalities, detected by the means of amino acid chromatography, are also given. Among these, cystinuria and peptiduria were equally prevalent and had the highest frequency. Of the disorders of carbohydrate metabolism, only cases of diabetes mellitus and renal glyco-suria were found.