Inherited conditions affecting the proteins of hair

Abstract

Hair abnormalities attracted attention quite early in the study of inborn errors of metabolism. The frequent occurrence of blonde hair in phenylketonuria is an obvious feature, and abnormal hair has been reported in argininosuccinic aciduria, citrullinaemia, argininaemia, homocystinuria, tyrosinaemia, Hartnup disease, and others. Before the mechanism of protein synthesis was clearly understood, it was considered possible that excess of an amino acid in tissue fluids could result in the synthesis of abnormal proteins with excess of that particular amino acid, and various proteins from phenylketonurics were analysed with this in mind (Block, Jervis, Bolling and Webb, 1940). It is now obvious that with a few exceptions (such as the substitution of unnatural fluoro analogues for the correct amino acid) the composition of proteins cannot be changed in this way. Hair is a peculiar tissue, however, and interest in its composition in inborn errors of metabolism has continued. This is partly because of direct clinical observation of hair texture and colour changes during treatment in a number of these conditions, and perhaps also because of possible analagies with the selective accumulation of some trace metals.