Mellman et al. (1963) found indolylacroyl glycinuria in 5 mentally retarded sibs. The mother also excreted the substance. Tryptophane loading orally or intravenously did not increase the excretion but oral neomycin caused disappearance of the substance from the ... Mellman et al. (1963) found indolylacroyl glycinuria in 5 mentally retarded sibs. The mother also excreted the substance. Tryptophane loading orally or intravenously did not increase the excretion but oral neomycin caused disappearance of the substance from the urine in 4 of the 5 sibs. The substance would appear to be derived from the bowel, where it is probably a product of bacterial action, and may find its way into the blood and urine because of a specific transmucosal transport defect as in Hartnup disease.