The effect of UGT1A1 promoter polymorphism on bilirubin response to hydroxyurea therapy in hemoglobinopathies

Abstract

Objectives Hydroxyurea is known to reduce ineffective erythropoiesis and thereby hemolysis leading to a reduction in bilirubin levels in patients with hemoglobinopathies. However, the effect of hydroxyurea on hyperbilirubinemia in relation to the UGT1A1 gene promoter polymorphism is not known in Indian patients with different hemoglobinopathies. Design and methods We studied 112 patients (77 sickle cell anemia, 22 β-thalassemia intermedia and 13 HbE-β-thalassemia) who were on hydroxyurea therapy for 2 years for their response towards hyperbilirubinemia associated with UGT1A1 promoter polymorphism. Results The patients with (TA) 7/(TA) 7 repeats had significantly higher serum bilirubin levels than those with (TA) 6/(TA) 6 repeats in all the groups and the reduction in serum bilirubin after hydroxyurea therapy was still higher among patients with (TA) 7/(TA) 7 repeats when compared with (TA) 6/(TA) 6 repeats. Conclusions Higher bilirubin levels were associated with the (TA) 7/(TA) 7 sequence however they did not come down to normal levels after hydroxyurea therapy.