Metabolic Study of an Alkaptonuric Infant.

Alkaptonuria is an extremely rare condition, which is due to a defect in protein metabolism. The most probable explanation is that it is due to the absence of the particular enzyme which normally effects a particular stage in the complete destruction of tyrosine and phenyl-alanine. Alkapton is the intermediate product beyond which metabolism can no further go, and it is excreted as such in the urine. The d-fect is congenital and it is inherited, although the line of inheritance is difficult to trace. Transmission is seldom direct from parent to child, but several children in one family may be affected. Consanguinity between parents seems to have some responsibility for its occurrence. It is probably a Mendelian recessive characteristic. It is more common in males than in females. It may give rise to pigmentation of the cartilages and to arthritis. Very little has been written on the subject since the publication of Sir Archibald Garrod'sl book on ' Inborn Errors of Metabolism ' in 1923. There he recounts the development of the knowledge of this metabolic disorder since the discovery in 1858 by Bodeker of a second reducing substance in the urine of a diabetic. He called it alkapton. In 1891, Wolkow and Baumann showed that the reducing substance was homogentisic acid, with the empirical formula C8H804. This has been confirmed by several other workers, and its constitution definitely proved to be that of hydroquinone-acetic acid, with the following formula: