Tyrosinemia

Abstract

Abstract In 1932 the term tyrosinemia was first used to describe a single patient with constant urinary excretion of large quantities of tyrosine and the tyrosine metabolites, p-hydroxy phenyllactic (p-HPLA) and p-hydroxy phenylpyruvic acids (p-HPPA),1 which together are called tyrosyluria. Subsequent to this description, several conditions resulting from different defects were found to produce the biochemical features of tyrosinemia and tyrosyluria. So far, five defects in the catabolic pathway of tyrosine metabolism have been described (Fig. 40–1). All of these defects are transmitted as autosomal recessive traits. Apart from tyrosinemia types I, II, and III, alkaptonuria and maleylacetoacetate isomerase (MAA) deficiency have been described, the last being reported in one paper, the problems corresponding with tyrosinemia type I. Therefore, this chapter does not describe the problems related to MAA deficiency.