Allele and genotype frequency of a genetic variant in ATM gene affecting glycemic response to metformin in South Indian population.Context:The novel polymorphism in ATM gene (rs11212617), which is implicated to have association with metformin response, exhibits inter-ethnic variability in the allele and genotype frequency distribution.Aims and Design:The objective of the present study is to establish the allele and genotype frequency of rs11212617 single nucleotide polymorphism in ATM gene, in South Indian population and to find if this variant has any role in the etiology of type 2 diabetes mellitus.Materials and Methods:The study was performed in 2 cohorts of populations, 112 healthy volunteers and 118 type 2 diabetes mellitus patients. Genomic deoxyribonucleic acid (DNA) was extracted from peripheral blood leucocytes by phenol-chloroform method and genotyping was performed by real-time polymerase chain reaction using TaqMan assay.Results:In South Indian population, the frequency of major A allele was 0.65 and the minor C allele was 0.35. AA and CC are the homozygous genotypes with frequency of 0.39 and 0.09 respectively. The frequency of heterozygous genotype AC (0.52) was found to be higher than the homozygotes. There was no significant difference in the frequency distribution in the diabetic population, which implies that this variant does not have any causative role in the disease etiology. The frequency distributions were found to be significantly different from the distributions in other ethnic populations such as Caucasians, Chinese, Japanese and Africans. But there was no significant difference when compared with the Gujarati Indians of Houston.Conclusion:The frequency distribution of this novel variant in South Indian population forms a framework for further gene disease association studies to establish the association of this variant with metformin response. Our study could not find any association of this variant with respect to the disease etiology.

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Background:Genetic polymorphisms of the angiotensin-renin pathway have been thought to influence the development of diabetic nephropathy. However, there are conflicting results regarding this association in previous studies on populations with varying ethnicity.Aims:Primary aim was to compare the frequency of distribution of angiotensin-converting enzyme (ACE) gene (insertion/deletion [I/D]) polymorphism in Tamilian Indian type 2 diabetic individuals with and without microalbuminuria. Secondary objective was to compare the frequency of distribution of the 3 genotypes in diabetic patients with urinary albumin/creatinine ratio (ACR) < 30 mg/dL, urinary ACR = 30 to 300 mg/dL, and urinary ACR > 300 mg/dL.Methods:A total of 179 consecutive diabetic individuals between 40 and 70 years, from Puducherry and Tamilnadu of Dravidian descent participated in the study conducted from 2012 to 2014. Inclusion criteria were as follows: age ≥ 40 years and duration of type 2 diabetes mellitus for ≥5 years. Patients were divided into 2 groups based on ACR values. Group 1 consisted of 50 individuals with urinary ACR < 30 mg/g of creatinine, and group 2 consisted of 129 individuals with urinary ACR > 30 mg/g. Angiotensin I–converting enzyme (ACE) gene polymorphism was determined by allele-specific polymerase chain reaction method using a primer pair flanking the polymorphic region of its intron 16. Furthermore, group 2 patients were subdivided into those with urinary ACR = 30 to 300 mg/g of creatinine and those with urinary ACR > 300 mg/g of creatinine, and distribution of ACE gene polymorphism was compared in the three groups.Statistics:Statistical analysis was done using SPSS version 17.0. Independent Student t test was used to compare mean values between the 2 groups. Odds ratio was calculated for testing association between ACE gene (I/D) polymorphism and presence of microalbuminuria. P < .05 was considered significant. Comparison of ACE genotypes among 3 groups of patients (ACR < 30 mg/g, ACR = 30-300 mg/g, and ACR > 300 mg/g) was done using 1-way analysis of variance with Bonferroni multiple comparison test as post hoc analysis.Conclusions:Heterozygous I/D genotype was more frequent in the study population (45.8%) than the other genotypes. There was no difference in the genotype distribution in patients with varying levels of albuminuria.

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