Biochemical Approaches to Mental Handicap in Children:

This small book consists of seven papers which vary in subject matter, technique and quality. Some present new work; others review briefly the recent literature.

Dr. Nina A. J. Carson, the discoverer of homocystinuria, discusses again her survey of retarded persons in Northern Ireland. She has employed simple qualitative tests and amino acid two-dimensional chromatographic analysis of urine to screen for metabolic defects in retarded subjects. She concludes that the ferric chloride test for PKU, the phenylhydrazine test for keto acids, the cyanidenitroprusside test for sulfur-containing amino acids, and tests for urinary protein and sugar are most useful and should be combined with amino acid analysis. An important point which many have overlooked is the ease with which amino acid chromatographers can miss homocystine unless the qualitative test for sulfhydryl containing amino acids is also performed. Dr. Carson documents an incidence of PKU of 10 in