In 1957 Sakai and Kitagawa in Japan reported the clinical and biochemical findings in a patient with tyrosinemia, tyrosyluria, liver cirrhosis, and renal rickets. Subsequently, reports were published from various countries of other patients with hepatorenal tyrosinemia (HRT). 4-Hydroxyphenylpyruvate dioxygenase deficiency was originally proposed as the cause of HRT. However, in 1977 Lindblad et al. found that succinylacetone, which accumulates in the serum and urine from patients with HRT, inhibits delta-aminolevulinic acid (ALA) dehydratase in vitro. They suggested that the primary enzyme deficiency in patients with HRT was fumarylacetoacetate hydrolase, and this was soon confirmed. Thus, the elucidation of the pathogenesis of this disease has led to the possibility that, if a reliable newborn screening method could be developed, the prognosis of these patients would be improved. Early treatment would require a diet low in phenylalanine and tyrosine, administration of 2-(2-nitoro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC), and liver transplantation.

(Communicated by Kunihiko SUZUKI, M.J.A.)