Association of single nucleotide variants of the SLCO1B1 gene with the Gilbert syndrome phenotype

The aim of the study is to investigate the association of rs2306283 and rs4149056 variants of the SLCO1B1 gene with benign unconjugated hyperbilirubinemia. Materials and methods . A case-control study design was employed. The group with the Gilbert syndrome (GS) phenotype comprised 414 individuals (mean age 36.7 ± 15.9 years, 49.8% men). The control group consisted of 429 individuals (mean age 38.5 ± 14.3 years, 52.2% men) randomly selected from DNA banks of MONICA project participants, young adults aged 25–44 years, and participants in a cross-sectional study of schoolchildren in Novosibirsk. Genotyping of the groups for nucleotide sequence variants rs2306283 and rs4149056 of the SLCO1B1 gene was performed using real-time polymerase chain reaction. Results . No statistically significant differences were found between the GS and control groups regarding the frequencies of genotypes and alleles of rs2306283 (p > 0.05). Carriers of the TT rs4149056 genotype were less common (OR = 0.67, 95% CI 0.51–0.89, p = 0.005), while carriers of the TC genotype were more prevalent (OR = 1.46, 95% CI 1.1–1,94, p = 0.009) in the GS group compared to the control group. The frequency of the C allele rs4149056 was higher in the GS group compared to the control group (OR = 1.35, 95% CI 1.07–1.7, p = 0.012). These differences persisted for carriers of the 6TA/7TA genotype but not for the 6TA/6TA and 7TA/7TA genotypes rs3064744 of the UGT1A gene. Conclusion . The single nucleotide variant rs2306283 of the SLCO1B1 gene is not associated with benign unconjugated hyperbilirubinemia. The TC genotype and C allele of the single nucleotide variant rs4149056 of the SLCO1B1 gene are the genotype and risk allele of Gilbert syndrome, while the TT variant genotype exhibits a protective effect against the development of the syndrome, particularly for carriers of the 6TA/7TA genotype rs3064744 of the UGT1A gene.