Introduction
Interest in the detection of free amino acids in the urine has been stimulated by the development of chromatographic techniques.1-5 As a result, new genetically determined conditions have been described, such as glycinuria6 and "Hartnup" disease.7 A number of well-known diseases have been further characterized by the excretion of increased or abnormal amino acids in the urine, as in rickets, scurvy, galactosemia, Wilson's disease, lead poisoning, and burns. The detection of amino-aciduria in certain mentally disturbed children8,9 offers a new biochemical approach in the study of the basic disturbance and may even suggest genetic implications. Reference to the occurrence of amino-aciduria in patients with mental disturbances can be found in the studies on phenylketonuria10,11 and Lowe's syndrome,12 and in the reports by Allan et al.8 and by Sutton and Read.9 In this report we shall discuss the principles of paper chromatography, summarize