Implication of critical pharmacokinetic gene variants on therapeutic response to metformin in Type 2 diabetes.

AIM: Metformin, an oral hypoglycemic drug is the first line of treatment for Type 2 diabetes individuals. We studied the effect of critical gene single nucleotide polymorphisms  on the glucose lowering effect of metformin. METHOD: We performed a prospective study on 221 newly diagnosed, treatment-naive Type 2 diabetes subjects. Individuals were started with metformin monotherapy and followed up for 12 weeks. RESULTS: Our association analysis revealed that SLC22A2 rs316019 and SLC47A2 rs12943590 were significantly associated with metformin drug response across co-dominant and dominant models, respectively. SLC22A2 rs316019 GG and SLC47A2 rs12943590 GA combined genotypes showed maximum average change in HbA1c level. CONCLUSION: The present study proposes a role of SLC22A2 rs316019 and SLC47A2 rs12943590 in the pharmacokinetic action of metformin.

Elevated homocysteine levels in type 2 diabetes induce constitutive neutrophil extracellular traps.

Constitutively active neutrophil extracellular traps (NETs) and elevated plasma homocysteine are independent risk factors for Type 2 Diabetes (T2D) associated vascular diseases. Here, we show robust NETosis due to elevated plasma homocysteine levels in T2D subjects and increased components of NETs such as neutrophil elastase and cell free DNA. Cooperative NETs formation was observed in neutrophils exposed to homocysteine, IL-6 and high glucose suggesting acute temporal changes tightly regulate constitutive NETosis. Homocysteine induced NETs by NADPH oxidase dependent and independent mechanisms. Constitutively higher levels of calcium and mitochondrial superoxides under hyperglycemic conditions were further elevated in response to homocysteine leading to accelerated NETosis. Homocysteine showed robust interaction between neutrophils and platelets by inducing platelet aggregation and NETosis in an interdependent manner. Our data demonstrates that homocysteine can alter innate immune function by promoting NETs formation and disturbs homeostasis between platelets and neutrophils which may lead to T2D associated vascular diseases.

Replication and Relevance of Multiple Susceptibility Loci Discovered from Genome Wide Association Studies for Type 2 Diabetes in an Indian Population.

AIM: Several genetic variants for type 2 diabetes (T2D) have been identified through genome wide association studies (GWAS) from Caucasian population; however replication studies were not consistent across various ethnicities. Objective of the current study is to examine the possible correlation of 9 most significant GWAS single nucleotide polymorphisms (SNPs) for T2D susceptibility as well as the interactive effect of these variants on the risk of T2D in an Indian population. METHODS: Case-control cohorts of 1156 individuals were genotyped for 9 SNPs from an Indian population. Association analyses were performed using logistic regression after adjusting for covariates. Multifactor dimensionality reduction (MDR) analysis was adopted to determine gene-gene interactions and discriminatory power of combined SNP effect was assessed by grouping individuals based on the number of risk alleles and by calculating area under the receiver-operator characteristic curve (AUC). RESULTS: We confirm the association of TCF7L2 (rs7903146) and SLC30A8 (rs13266634) with T2D. MDR analysis showed statistically significant interactions among four SNPs of SLC30A8 (rs13266634), IGF2BP2 (rs4402960), HHEX (rs1111875) and CDKN2A (rs10811661) genes. Cumulative analysis showed an increase in odds ratio against the baseline group of individuals carrying 5 to 6 risk alleles and discriminatory power of genetic test based on 9 variants showed higher AUC value when analyzed along with body mass index (BMI). CONCLUSION: These results provide a strong evidence for independent association between T2D and SNPs for in TCF7L2 and SLC30A8. MDR analysis demonstrates that independently non-significant variants may interact with one another resulting in increased disease susceptibility in the population tested.

Implications of critical PPARγ2, ADIPOQ and FTO gene polymorphisms in type 2 diabetes and obesity-mediated susceptibility to type 2 diabetes in an Indian population.

Peroxisome proliferator-activated receptors (PPARγ), adiponectin (ADIPOQ) and fat mass and obesity-associated gene (FTO) have been reported as a key candidate genes for obesity, type 2 diabetes (T2D) susceptibility and insulin resistance, and we hypothesize that in the background of obesity, the effect of PPARγ2 (rs1801282), ADIPOQ (rs16861194) and FTO (rs9939609) variant could potentially influence T2D susceptibility. To decipher a more accurate estimation toward its population-specific impact of these variants toward susceptibility to T2D, a case-control study, systematic review and a meta-analysis was performed in a South Asian population. A case-control analysis of 518 T2D cases and 518 controls of Karnataka origin were performed to analyze the association of PPARγ2 (rs1801282), ADIPOQ (rs16861194) and FTO (rs9939609) on the risk of T2D. In addition, a systematic review and meta-analysis for PPARγ2 (rs1801282) and FTO (rs9939609) was elucidated from Asian population. Our investigation showed that PPARγ2 (rs1801282) and FTO (rs9939609) are associated with T2D susceptibility. When T2D cohort was further stratified according to the obesity status, PPARγ2 (rs1801282) and FTO (rs9939609) showed association with T2D only in the obese diabetic group and ADIPOQ (rs16861194) showed no difference in risk of susceptibility to the disease. The meta-analysis of PPARγ2 (rs1801282) showed population-specific association for T2D susceptibility as opposed to FTO (rs9939609) which showed no difference in population effect toward T2D susceptibility. In conclusion, our study showed that PPARγ2 (rs1801282) and FTO (rs9939609) variants are associated with T2D susceptibility when associated with adiposity in Indian population.

Population specific impact of genetic variants in KCNJ11 gene to type 2 diabetes: a case-control and meta-analysis study.

BACKGROUND AND OBJECTIVES: Potassium inwardly rectifying channel, subfamily J, member 11 (KCNJ11) gene have a key role in insulin secretion and is of substantial interest as a candidate gene for type 2 diabetes (T2D). The current work was performed to delineate the genetic influence of KCNJ11 polymorphisms on risk of T2D in South Indian population through case-control association study along with systematic review and meta-analysis. METHODS: A case-control study of 400 T2D cases and controls of South Indian origin were performed to analyze the association of KCNJ11 polymorphisms (rs5219, rs5215, rs41282930, rs1800467) and copy number variations (CNV) on the risk of T2D. In addition a systematic review and meta-analysis for KCNJ11 rs5219 was conducted in 3,831 cases and 3,543 controls from 5 published reports from South-Asian population by searching various databases. Odds ratio with 95% confidence interval (CI) was used to assess the association strength. Cochran's Q, I2 statistics were used to study heterogeneity between the eligible studies. RESULTS: KCNJ11 rs5215, C-G-C-C haplotype and two loci analysis (rs5219 vs rs1800467) showed a significant association with T2D but CNV analysis did not show significant variation between T2D cases and control subjects. Lower age of disease onset (P = 0.04) and higher body mass index (BMI) (P = 0.04) were associated with rs5219 TT genotype in T2D patients. The meta-analysis of KCNJ11 rs5219 on South Asian population showed no association on susceptibility to T2D with an overall pooled OR = 0.98, 95% CI = 0.83-1.16. Stratification analysis showed East Asian population and global population were associated with T2D when compared to South Asians. CONCLUSION: KCNJ11 rs5219 is not independently associated with T2D in South-Indian population and our meta-analysis suggests that KCNJ11 polymorphism (rs5219) is associated with risk of T2D in East Asian population and global population but this outcome could not be replicated in South Asian sub groups.