Bilirubin concentrations in thalassemia heterozygotes in university students

Objectives:  To investigate the difference of bilirubin concentrations between α‐ and β‐thalassemia carriers and the role of variation status in the UDP‐glucuronosyltransferase (UGT) 1A1 gene on such a difference. Methods:  A total of 2713 university freshmen who attended a regular physical examination were enrolled in underwent screenings for thalassemias. Finally, 123 subjects whose mean corpuscular volume was ≤80 fL and who had no iron deficiency anemia were tested by PCR and PCR–restriction fragment length polymorphism (RFLP) for α‐ and β‐thalassemias, respectively, and tested by PCR–RFLP for the five known variations of the UGT1A1 gene. Results:  Among the 123 subjects, 76 and 47 were diagnosed with heterozygous α‐thalassemia and with heterozygous β‐thalassemia, respectively. Between the α‐ and β‐thalassemia heterozygotes, variation status of the UGT1A1 gene was not statistically different ( P  =   0.898), while hemoglobin and bilirubin concentrations differed significantly ( P  =   0.005 and 0.001, respectively). Bilirubin concentrations were significantly higher among individuals with compound heterozygous variations/homozygous variation in the UGT1A1 gene than in those possessing the wild type and heterozygous variation ( P  <   0.001 for both α‐ and β‐thalassemia heterozygotes). Compound heterozygous variations/homozygous variation in the UGT1A1 gene and anemia were the main causes of hyperbilirubinemia in α‐ and β‐thalassemia heterozygotes, respectively. Conclusions:  The difference in bilirubin concentrations between α‐ and β‐thalassemia heterozygotes may be attributable to more bilirubin being produced in β‐thalassemia heterozygotes than in α‐thalassemia heterozygotes, while variation status of the UGT1A1 gene affects bilirubin concentrations in both α‐ and β‐thalassemia heterozygotes.