Genotype Frequencies of C1236t Polymorphism of the ABCB1 Gene in Various Ethnic Groups of Pakistan

Background and Objective: The ATP binding Cassette group B gene 1 (ABCB1) encodes for a P-glycoprotein (P-gp), which acts as an efflux pump for many drugs. Among the several single nucleotide polymorphisms (SNPs) reported for the ABCB1gene C1236T is a silent but functional polymorphism. This polymorphism is known to influence the expression and function of P-gp, and thus affect the pharmacokinetics and dynamics of the substrate drugs. The aim of the current study was to analyze and compare for the first time an existing silent ABCB1 C1236T polymorphism in six ethnic groups of Pakistan. Study design: A cross-sectional study. Place and Duration of study: Combined Military Hospital, Rawalpindi and Institute of Biomedical and Genetic Engineering, Islamabad in year 2012-2013 Methods: A total of four hundred and twenty six unrelated healthy subjects (220 females, 206 males) were included in this study. They were divided into six groups; Punjabi, Sindhi, Balouchi, Pathan, Kashmiri and Gilgit/Baltistanis. The genotyping of the C1236T SNP was performed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. Results: The genotype frequency of the analyzed SNP was as follows: 16.4% for CC, 44.1% for CT and 39.4% for TT. The distribution of C1236T genotype frequencies in our study groups was found to be similar between the six groups. There was no significant difference in the genotypes on the basis of ethnicity (p= 0.520). Conclusion: Our study provides a framework for future studies concerning the role of polymorphic variant of ABCB1gene. Our results for the Pakistani population could be relevant for further investigation of drugs that are substrates of P-gp and for studies of interethnic diversity in ABCB1polymorphism frequency.