[Arginase deficiency, congenital hypothyroidism and hepatic fibrosis].

A new case of arginase deficiency in a newborn is reported. In contrast with previous cases, this infant showed severe protein intolerance of early onset. Diagnosis was based on the assay of urea cycle enzymes in a postmortem liver sample and on arginase activity in erythrocytes of parents and sister of the patient. "Pedigree" shows that arginase deficiency in this family presents a dramatic course. Congenital hypothyroidism with athyreosis, moderate hepatic fibrosis and megamitochondria are present in the same subject. Possible significance of these findings is briefly discussed.