Gilbert syndrome associated with beta-thalassemia

Area of Science:

• Genetics
• Hematology
• Biochemistry

Background:

• Beta-thalassemia is a group of inherited blood disorders characterized by reduced or absent synthesis of beta-globin chains.
• Significant variability in serum bilirubin levels (STB) is observed in patients with transfusion-dependent beta-thalassemia, beta-thal intermedia, and heterozygous beta-thalassemia.
• Gilbert syndrome (GS) is a common genetic condition affecting bilirubin metabolism.

Purpose of the Study:

• To investigate the potential association between Gilbert syndrome and the variability of serum bilirubin levels in different forms of beta-thalassemia.
• To analyze the promoter region of the bilirubin UDP-glucuronosyltransferase gene (UGT1A1) in beta-thalassemia individuals and controls.

Main Methods:

• Genotyping of the UGT1A1 promoter region [A(TA)nTAA] was performed.
• The study included 128 beta-thalassemia individuals (108 transfusion-dependent, 20 intermedia) and 33 beta-thalassemia heterozygotes.
• A control group of 70 healthy children was also analyzed.

Main Results:

• The frequency of the Gilbert syndrome genotype (TA)7/(TA)7 did not significantly differ across the studied groups.
• Significant differences in serum bilirubin levels were observed between GS genotypes (TA)7/(TA)7 and (TA)6/(TA)7, and between (TA)7/(TA)7 and (TA)6/(TA)6.
• These associations were consistent across all examined groups.

Conclusions:

• The (TA)7/(TA)7 Gilbert syndrome genotype is a contributing factor to hyperbilirubinemia in transfusion-dependent beta-thalassemia, beta-thal intermedia, and heterozygous beta-thalassemia.
• This finding helps explain the variability in serum bilirubin levels observed in these patient populations.