Allele-Specific Detection of SLC22A2 rs316019 Variants Associated with Metformin Disposition through the Kidney

Background: Metformin is prescribed as a first-line drug to treat type 2 diabetes. It is excreted directly and primarily through the SLC22A2 gene-encoded OCT2 transporter in the kidney. rs316019 (c.808G>T, p.270A>S) is the most common variant of SLC22A2, which affects its capacity to clear metformin from the body. Metformin increases the plasma lactate level in a concentration-dependent manner by inhibiting mitochondrial respiration and may lead to a condition known as metformin-associated lactic acidosis (MALA). MALA is a potentially life-threatening complication that can occur within the clinical doses of metformin. Therefore, dose adjustments based on the SLC22A2 rs316019 variants may be beneficial to maximize the efficacy and minimize the toxicity of metformin. Objective: This study was carried out to develop a simple and fast method to define genotype at the rs316019 locus. This method was applied to estimate the rs316019 allele frequencies in the Bangladeshi population. Methods: We designed allele-specific primers to determine genotype at the rs316019 locus using allele-specific polymerase chain reaction (AS-PCR). AS-PCR data were confirmed by targeted sequencing of randomly selected samples. Results: The DNA sequence chromatograms showed the exact genotypes predicted through the AS-PCR method. A proportion of 79.62, 18.01, and 2.37% of Bangladeshi individuals have GG, GT, and TT genotypes, respectively. Conclusion: We report here a simple and fast method to define genotypes at the rs316019 locus in diabetic patients who are under metformin regimen. Allele frequencies at the rs316019 locus in the Bangladeshi population are close to those reported in other populations.