Gilbert's syndrome accounts for the phenotypic variability of congenital dyserythropoietic anemia type II (CDA-II)

The molecular basis for the considerable variation of serum bilirubin level s and the incidence of gallstone formation in patients with congenital dyse rythropoietic anemia (CDA) type II are unknown. We show that the combined e ffect of an increased bilirubin load caused by dyserythropoiesis in CDA II and decreased bilirubin conjugation caused by reduced expression of ur;dine diphosphate glucuronosyl transferase (UGT1A) would increase the risk of hy perbilirubinemia (P <.005) and gallstone formation (chi(2): P < .001). The rate of gallstone formation in patients with CDA II is 4.75-fold the rate o f patients without Gilbert's syndrome, and gallstone diagnosis occurs at a younger age (P < 0.01). These findings should be considered during the foll ow-up of patients with CDA II.