Association of rs3755319 and rs4148325 of the <i>UGT1A1</i> gene, rs2328136 of the <i>NUP153-AS</i> gene, and rs16928809 of the <i>SLC22A18</i> gene with benign unconjugated hyperbilirubinemia

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Background: Benign unconjugated hyperbilirubinemia, also known as Gilbert's syndrome, is a common in the population moderate increase in total and unconjugated bilirubin concentrations in individuals without liver disease or hemolysis. Aim: To identify associations of rs3755319, rs4148325 of the UGT1A1 gene, rs2328136 of the NUP153-AS gene, and rs16928809 of the SLC22A18 gene with benign unconjugated hyperbilirubinemia. Methods: This case-control study included a group of individuals with benign unconjugated hyperbilirubinemia (n = 414, mean age 36.7 ± 15.9 years, 49.8% men) and a control group (n = 381, mean age 39.1 ± 15.9 years, 52.5% men). The sample was randomly selected from the participants of the MONICA project, screening of young people aged 25–44 years and a cross-sectional study of schoolchildren in Novosibirsk. DNA was isolated from venous blood by phenol-chloroform extraction or an express assay (PROBA-RAPID-GENETICS, DNA-Technology, Russia). Genotyping of the groups by rs3755319, rs4148325 of the UGT1A1 gene, rs2328136 of the NUP153-AS gene, and rs16928809 of the SLC22A18 gene was performed by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results: No significant differences were found between the individuals with benign unconjugated hyperbilirubinemia and the control group by the genotypes and alleles of the nucleotide sequence variants of rs16928809 of the SLC22A18 gene (p 0.05). The CC genotype and the C allele of rs3755319 of the UGT1A1 gene were more common in the individuals with benign unconjugated hyperbilirubinemia, than in the control group (CC vs AC + AA: odds ratio (OR) = 21.1, 95% confidence interval (CI) 14.7–30.4, p 0.001; C vs A: OR = 12.4, 95% CI 9.4–16.4, p 0.001). The concentrations of total and unconjugated bilirubin were higher in the carriers of the CC genotype of rs3755319, compared to the carriers of the other two genotypes (p 0.05). rs4148325 of the UGT1A1 gene was in the linkage disequilibrium with the rs3064744 UGT1A1 variant. The GG genotype and the G allele rs2328136 of the NUP153-AS gene were more common in the individuals with benign unconjugated hyperbilirubinemia than in the control group (GG vs AG + AA: OR = 1.361, 95% CI 1.002–1.848, p = 0.048; G vs A: OR = 1.33, 95% CI 1.02–1.73, p = 0.034). Conclusion: The CC genotype and the C allele of rs3755319 of the UGT1A1 gene, the GG genotype and the G allele of rs2328136 of the NUP153-AS gene are the genotypes and alleles of risk for benign unconjugated hyperbilirubinemia. The rs16928809 of the SLC22A18 gene is not associated with benign unconjugated hyperbilirubinemia.