GILBERT SYNDROME ASSOCIATED WITH β-THALASSEMIA

The authors investigated whether the considerable variability in serum bilirubin levels (STB) found in transfusion-dependent β-thalassemia, β-thal intermedia, and heterozygous β-thalassemia individuals could be related to the coexistence of Gilbert syndrome (GS). The promoter region [A(TA) n TAA] of the bilirubin UDP-glucuronosyltransferase gene (UGT1A1) was analyzed in a total of 128 β-thalassemia individuals (108 transfusion-dependent β-thal patients, 20 very mild β-thal intermedia) and in 33 β-thal heterozygotes. The control group consisted of 70 healthy children with no history of anemia. The frequency of GS genotype (TA) 7 /(TA) 7 did not differ significantly between the groups studied. A significant difference was observed between serum bilirubin levels (STB) and GS genotypes (TA) 7 /(TA) 7 and (TA) 6 /(TA) 7 and also between (TA) 7 /(TA) 7 and (TA) 6 /(TA) 6 for all groups examined. These results confirm that the (TA) 7 /(TA) 7 GS genotype is one of the factors accounting for the hyperbilirubinemia observed in β-thalassemia major, intermedia, and heterozygous individuals.