HEREDITARY TYROSINEMIA

Summary The clinical and biochemical findings in the case of an infant with hereditary tyrosinemia followed from birth have been reported. The child received a low protein diet from birth and a formula diet restricted in phenylalanine and tyrosine when the diagnosis was established at 54 days of age. There was a steady progress of the disease and the baby died from liver failure complicated with septicemia when he was 5½ months old. The clinical course and the biochemical findings as well as the morphological changes were typical of the acute type of the disease. A 6½ year old brother suffers from the same disease of the chronic type and the two types of hereditary tyrosinemia therefore seem to belong to the same genotype. The biochemical data from the patient with hereditary tyrosinemia have been compared with those in a healthy looking baby with longstanding and pronounced transient tyrosinemia of early infancy. The patterns of amino acids in blood and of phenolic acids in urine were similar in the two patients and it is concluded that an early laboratory differential diagnosis between hereditary tyrosinemia and transient tyrosinemia may only be made by observing the biochemical response to a diet restricted in tyrosine and phenylalanine in combination with the results of phenylalanine tolerance tests. The clinical features of hereditary tyrosinemia can apparently not be attributed to a high serum‐tyrosine concentration or to the overproduction of phenolic acids; the lack of effect of early restriction in the intake of phenylalanine and tyrosine indicates a more complex pathogenesis of hereditary tyrosinemia than a primary deficiency of p‐hydroxyphenylpyruvate hydroxylase.