Crigler-Najjar syndrome type II. New observation of possible autosomal recessive inheritance.

The inheritance of Crigler-Najjar syndrome type II (CNS II) is still unclear. Both autosomal dominant transmission with variable penetrance and autosomal recessive transmission have been reported. We describe the diagnosis of CNS II in an adult patient with unconjugated serum bilirubin levels up to 19.6 mg/dl and no detectable activity of bilirubin UDP-glucuronosyltransferase in the liver biopsy. Serum bilirubin levels decreased markedly on phenobarbital treatment. The parents of our patient are first cousins. The mother and three of the patient's five sibs were jaundiced within a few days of birth. Our patient and her jaundiced siblings have 11 children, all healthy and anicteric. We conclude from these data that the inheritance of this very rare disease follows an autosomal recessive pattern, with pseudodominance in this family.