Implications of genetic variations, differential gene expression, and allele-specific expression on metformin response in drug-naïve type 2 diabetes.

PURPOSE: Metformin is widely used to treat type 2 diabetes mellitus (T2DM) individuals. Clinically, inter-individual variability of metformin response is of significant concern and is under interrogation. In this study, a targeted exome and whole transcriptome analysis were performed to identify predictive biomarkers of metformin response in drug-naïve T2DM individuals. METHODS: The study followed a prospective study design. Drug-naïve T2DM individuals (n = 192) and controls (n = 223) were enrolled. T2DM individuals were administered with metformin monotherapy and defined as responders and non-responders based on their glycated haemoglobin change over three months. 146 T2DM individuals were used for the final analysis and remaining samples were lost during the follow-up. Target exome sequencing and RNA-seq was performed to analyze genetic and transcriptome profile. The selected SNPs were validated by genotyping and allele specific gene expression using the TaqMan assay. The gene prioritization, enrichment analysis, drug-gene interactions, disease-gene association, and correlation analysis were performed using various tools and databases. RESULTS: rs1050152 and rs272893 in SLC22A4 were associated with improved response to metformin. The copy number loss was observed in PPARGC1A in the non-responders. The expression analysis highlighted potential differentially expressed targets for predicting metformin response (n = 35) and T2DM (n = 14). The expression of GDF15, TWISTNB, and RPL36A genes showed a maximum correlation with the change in HbA1c levels. The disease-gene association analysis highlighted MAGI2 rs113805659 to be linked with T2DM. CONCLUSION: The results provide evidence for the genetic variations, perturbed transcriptome, allele-specific gene expression, and pathways associated with metformin drug response in T2DM.

Genetic Variants Identified from GWAS for Predisposition to Type 2 Diabetes Predict Sulfonylurea Drug Response.

BACKGROUND: Several SNPs were identified through GWAS for their association with type 2 diabetes which has implications to pancreatic ß-cell physiology. OBJECTIVE: We aimed to study the role of risk alleles of TCF7L2, KCNJ11, CDKN2A, CDKAL1, IGF2BP2, SLC30A8 and KCNQ1 along with pharmacokinetic variants in response to sulfonylureas. METHOD: We performed a prospective study on 209 newly diagnosed subjects; treatment naive T2D subjects were recruited. Individuals were started with glibenclamide monotherapy and followed-up for 12 weeks. Genotyping was done, using PCR-RFLP and TETRA-ARMS PCR and confirmed by DNA sequencing. RESULTS: In univariate regression analysis, KCNJ11 (rs5219) was only the predictor for glibenclamide treatment failure. CONCLUSION: The present data suggests a possible role of KCNJ11 gene in altered response to glibenclamide.