Infant with Features of Tyrosinosis

Tyrosinosis has been recognized with increasing frequency in recent years, and the disease is characterized by cirrhosis of the liver, renal tubular dysfunction, and hypophosphataemic rickets. These features are associated with a disturbance of tyrosine metabolism thought to be due to a deficiency of the enzyme p-hydroxyphenylpyruvic acid oxidase (La Du, 1967); there is hypertyrosinaemia and hyperphenylalaninaemia, and tyrosine and related phenolic acids are excreted in excessive amounts in the urine. In the acute form of the disease, high blood levels of methionine have also been reported. The exact metabolic cause of the hypermethioninaemia is not understood, and this finding has often been associated with a poor prognosis (Halvorsen et al., 1966; Larochelle et al., 1967; Sass-Kortsak et al., 1967a). Treatment with a low-tyrosine low-phenylalanine diet is usually followed by rapid and marked improvement in renal function, and subsequent healing of rickets (Halvorsen et al., 1966; SassKortsak et al., 1967c), but its effectiveness in preventing the development of hepatic cirrhosis has not yet been established. In all cases so far reported attempts to terminate the dietary treatment have been followed by rapid clinical and biochemical relapse, and it has been assumed that long-term treatment is therefore essential (Fairney et al., 1968; Aronsson et al., 1968). We here report an infant in whom the diagnosis was made at the age of 5 months, and who had hypermethioninaemia. Dietary treatment resulted in an excellent clinical and biochemical response and it was subsequently possible to reintroduce a normal diet without relapse.