TYROSINOSIS: A PATIENT WITHOUT LIVER OR RENAL DISEASE

A child institutionalized because of severe mental retardation was found to have biochemical evidence of tyrosinosis. He has had no evidence of hepatic disease. In addition, he has had no hyperaminoaciduria, glycosuria, or rickets. Plasma tyrosine concentrations while he was on a regular diet ranged from 16.0 to 25.6 mg per 100 ml. Urinary excretion of tyrosine and tyrosine metabolites, including p-hydroxyphenylpyruvic acid, p-hydroxyphenyllactic acid, and p-hydroxyphenyl-acetic acid, were markedly increased. This patient appears to have a primary defect in tyrosine metabolism and represents individuals with persisting tyrosinemia and tyrosyluria in whom no hepatorenal disease is found.