[Biochemical diagnosis and mass screening for hereditary amino acid disorders].

During the past 50 years, the development of both organic and analytical chemistry has greatly contributed to the discovery of new hereditary amino acid disorders. As a result, more than 80 new amino acid disorders have been discovered. More recently, the development of protein chemistry has made it easily to investigate the biochemical basis of these disorders. In this paper we present the status of biochemical diagnosis as well as mass-screening for amino acid disorders. The result of neonatal mass-screening for 4 amino acid disorders (PKU, MSUD, homocystinuria and histidinemia) from 1977 to 1990 revealed that the incidence of PKU is extremely rare in Japan when compared to European Countries, and the incidence of MSUD and homocystinuria are also less common in Japan. On the other hand, the incidence of histidinemia is higher in Japan than in Europe, however, a follow up study of more than 1,500 patients showed almost all cases developed normally without any dietary treatment.