HEREDITARY TYROSINEMIA TYPE-I - A NEW CLINICAL CLASSIFICATION WITH DIFFERENCE IN PROGNOSIS ON DIETARY-TREATMENT

Hereditary tyrosinemia type I (McKusick 27670) is a heterogeneous dise ase with poor prognosis, yet there are few reports of the long-term pr ognosis. It is there fore difficult to decide on the treatment for ind ividual patients. We have conducted an international survey of patient s with tyrosinemia type I and examined the probability of survival on dietary treatment and the causes of death in 108 patients with tyrosin emia type I. The survival after the onset of symptoms varied with the age at onset; the earlier the symptoms developed the poorer the outloo k. Liver failure and recurrent bleeding (67%), hepatocellular carcinom a (17%) and the porphyria-like syndrome with respiratory failure (10%) were the most common causes of death. The 1-and 2-yr survival probabi lity after the onset of symptoms in patients in whom symptoms develope d before 2 mo, between 2 and 6 mo and after 6 mo were 38%/29%, 74%/74% and 96%/96%, respectively. On the basis of these survival rates, a ne w classification-which is important with respect to choices in treatme nt-is proposed: very early (onset of symptoms < 2 mo), early (2 to 6 m o) and late presenting form (> 6 mo).