Effects of SLC22A2 (rs201919874) and SLC47A2 (rs138244461) genetic variants on Metformin Pharmacokinetics in Pakistani T2DM patients

Objective: To determine the frequencies of single nucleotide polymorphisms rs201919874 and rs138244461 in genes SLC22A2 and SLC47A2 respectively in Pakistani diabetes patients in order to characterise the genetic variants and determine their association with the pharmacokinetics of metformin. Methods: The case-control study was conducted at the International Islamic University, Islamabad, Pakistan, from June 2016 to June 2017, and comprised genotypes of diabetic cases and matching controls which were determined following allele-specific polymerase chain reaction. Cases were further divided into Group A and Group B. The former consisted of diabetics who were on monotherapy of metformin, while the latter consisted of diabetics treated with a combination of metformin and sulfonylureas. In-silico analysis was performed to verify the effect of single nucleotide polymorphisms rs201919874 and rs138244461 on the structure of genes. Association was statistically determined using SPSS 18. Results: Of the 1200 subjects, 800(66.6%) were cases and 400(33.3%) were controls. Among the cases, 400(50%) each were in Group A and Group B. Significant difference was observed in the distribution of rs201919874 between Group A and controls (p<0.05) and between Group B and controls (p<0.05) for heterozygous genotypic frequency and for allelic frequency. Conversely, statistically significant difference was observed in rs138244461 (p<0.05) for all genotypic and allelic frequencies. Genotypes were significantly associated with glycated haemoglobin, random and fasting glucose levels in Group A compared to Group B (p<0.05). In-silico analysis showed that both single nucleotide polymorphisms were expected to create significantly damaging structural changes in domains and helix (p<0.05 each). Conclusions: Both exonic single nucleotide polymorphisms were found to be associated with the pharmacokinetics of metformin.