Kawaljit Matharoo

The Interactive Effect of SIRT1 Promoter Region Polymorphism on Type 2 Diabetes Susceptibility in the North Indian Population

Our previous studies have implicated genes mainly involved in the activity of pancreatic β cells in type 2 diabetes (T2D) susceptibility in the North Indian population. Recent literature on the role of SIRT1 as a potential master switch modulating insulin secretion and regulating gene expression in pancreatic β cells has warranted an evaluation of SIRT1 promoter region polymorphisms in the North Indian population, which is the main focus of the present study. 1542 samples (692 T2D patients and 850 controls) were sequenced for the 1.46 kb region upstream the translation start site of the SIRT1 gene. We performed a functional characterization of the SIRT1 promoter region polymorphisms using luciferase assay and observed a single-nucleotide polymorphism (SNP), rs12778366, in association with SIRT1 expression. We propose that TT, the high-expressing genotype of SNP rs12778366 in the SIRT1 promoter region and present in >80% of the North Indian population, was favored under conditions of feast-famine cycles in evolution, which has turned out to be a cause of concern in the present sedentary lifestyle under ad libitum conditions. Case-control association analysis did not implicate rs12778366 in T2DM per se in the studied population. However, our earlier reported risk genotype combinations of mt-ND3, PGC1α, and UCP2-866, when compared with the protective genotype combinations, in the background of the high-expressing TT genotype of SIRT1 SNP rs12778366, showed a very high additive risk [corrected odd ratio (OR) = 8.91; p = 6.5×10−11]. The risk level was considerably low in the genotype backgrounds of TX (OR = 6.68; p = 2.71×10−12) and CX (OR = 3.74; p = 4.0×10−3). In addition, we screened other reported T2D-associated polymorphisms: PIK3R1 rs3730089, IRS1 rs1801278, and PPP1R3 rs1799999, which did not show any significant association in North Indian population. The present paper emphasizes the importance of gene interactions in the biological pathways of T2D, a complex lifestyle disease.

Association of adiponectin (AdipoQ) and sulphonylurea receptor (ABCC8) gene polymorphisms with Type 2 Diabetes in North Indian population of Punjab.

In Type 2 Diabetes (T2D), adiponectin (AdipoQ) and sulphonylurea receptor genes (ABCC8) are important targets for candidate gene association studies. The single nucleotide polymorphisms (SNPs) in these genes have been associated with features of the metabolic syndrome across various populations. The present case-control study undertaken in the population of Punjab, evaluates the association of +45T>G polymorphism in AdipoQ gene; and Exon16-3C>T as well as Exon18C>T polymorphisms in ABCC8 gene with T2D. These SNPs were genotyped in 200 T2D cases and 200 non-diabetic healthy controls using the PCR-RFLP method. The frequency of the minor G-allele for AdipoQ+45(T>G) polymorphism was significantly higher in T2D cases (29.0%) than in controls (21.5%) [P=0.02, OR=1.49 (1.07-2.04)]. The genetic model analysis revealed that the G-allele cumulatively provides nearly 1.59-1.78 fold increased risk to T2D under the additive (P=0.009; OR=1.59, 1.12-2.25 at 95% CI), dominant (TG/GG vs. TT) (P=0.034, OR=1.64, 1.04-2.56 at 95% CI) and codominant model (TG vs. TT/GG) (P=0.014; OR=1.78, 1.12-2.82 at 95% CI) after adjusting for confounding factors. However, no difference in the distribution of genotype and allele frequencies was observed for both the ABCC8 polymorphisms. The distribution of obesity profiles (BMI, WC and WHR) was also significantly different between cases and controls (P<0.05). Higher BMI and central obesity were observed to increase the risk of T2D. G-allele of +45(T>G) polymorphism in the adiponectin gene appears to be associated with increased risk of T2D, but the polymorphisms in sulphonylurea receptor gene do not seem to be associated with T2D in the population of Punjab.

Association of −2518A>G Promoter Polymorphism in the Monocyte Chemoattractant Protein-1 (MCP-1) Gene with Type 2 Diabetes and Coronary Artery Disease

AIMS Inflammatory markers play an important role in the development of diseases related to metabolic syndrome, such as type 2 diabetes (T2D) and coronary artery disease (CAD). The present study evaluates the association of -2518A>G polymorphism in the monocyte chemoattractant protein-1 (MCP-1) gene with T2D and CAD. RESULTS The frequency of the G allele is greater in CAD cases (35%) as compared to T2D (24.6%) and controls (31%), while the frequency of the A allele is higher in T2D cases (75.4%) as compared to CAD cases (65%) and controls (69%). The analysis has revealed that in comparison to T2D cases, the G allele increases the risk of CAD by 1.9-fold (p=0.008; odds ratio [OR]=1.9, 1.18-3.06 at 95% confidence interval [CI]) but in comparison to controls the G-allele provided protection against T2D (p=0.011; OR=0.55, 0.35-0.87 at 95% CI), both under the dominant model (AG+GG vs. AA). CONCLUSION Results of the present study suggests that G-allele of MCP-1 -2518A>G polymorphism is associated with reduced risk of T2D and increased risk of CAD in the population of Punjab. The results indicate that there is a difference in the association of risk alleles with phenotypes of metabolic syndrome. Body mass index and waist circumference are important risk factors for T2D in the population of Punjab.

A Study of Angiotensin Converting Enzyme (ACE) Gene Polymorphism in Essential Hypertension among a Business Community in Punjab

Abstract The present study was carried out to investigate the association of the angiotensin-converting enzyme deletion/insertion polymorphism with hypertension and its role in increasing the susceptibility to hypertension among Bania population in Punjab. The study blood samples consisted of 50 normal (28 males and 22 females) healthy individuals and 50 hypertensive, age and sex matched (28 males and 22 females) individuals. The genotype frequencies were found to be 0.22, 0.32 and 0.46 for II, DD, ID genotype in hypertensives. The same has been found for normotensives to be 0.26, 0.18 and 0.56 for II, DD and ID respectively. The observed overall genotype distributions were consistent with Hardy-Weinberg equilibrium. The present analysis suggested that the genetic variation at the ACE gene may be associated with some determinants for blood pressure.

TNF-α (g.−308 G > A) and ADIPOQ (g. + 45 T > G) Gene Polymorphisms in Type 2 Diabetes and Microvascular Complications in the Region of Punjab (North–West India)

Abstract Aims: The present study aims to examine the association of tumor necrosis factor-α (TNF-α) g.−308 G > A and adiponectin (ADIPOQ) g. + 45 T > G gene polymorphisms in type 2 diabetes (T2D) and its microvascular complications diabetic retinopathy (DR) and diabetic nephropathy (DN). Materials and Methods: A total of 672 individuals were analysed from the North–West population of Punjab. Genotyping was accomplished by a combination of allele specific amplification refractory mutation system and restriction digestion for TNF-α g. − 308 G > A and ADIPOQ g. + 45 T > G polymorphisms, respectively. Further, in silico modeling was done to predict secondary structure of mRNA for g. + 45 T > G polymorphism in the ADIPOQ gene by RNA fold. Results: The minor allele frequency observed in the controls for the TNF-α G > A and ADIPOQ T > G polymorphisms were 0.07 and 0.10, respectively. The results show no significant association with TNF-α g. − 308 G > A polymorphism in T2D as well as in any of the microvascular complication. However, the ADIPOQ g. + 45 T > G polymorphism shows significant association in T2D (p = 0.048) and DR (p = 0.001) but in DN patients, no association was observed. Interactive analysis revealed that the two polymorphisms jointly conferred a 1.45-fold risk towards the occurrence of T2D [p = 0.031; OR = 1.45 (1.03–2.05)]. In the secondary structure of mRNA, slight free energy change was observed between the wild ( − 1370.28 kcal/mol) and variant allele (−1369.08 kcal/mol). Conclusions: Our results indicated a higher risk of T2D and DR in the background of ADIPOQ TT genotype. Further, the ADIPOQ g. + 45 T > G and TNF-α g. − 308 G > A polymorphisms jointly give 1.45-fold risk towards T2D.

C-reactive protein + 1059 G>C polymorphism in type 2 diabetes and coronary artery disease patients.

Human C-reactive protein (CRP) is an acute phase reactant involved in chronic and acute inflammation. CRP is associated with metabolic syndrome, obesity, atherosclerosis, unstable angina, insulin resistance and diabetes. The present study evaluates the association of + 1059 G>C silent polymorphism in exon 2 of CRP gene in 581 cases [CAD (206), T2D (266), T2D with CAD (109)] and 235 controls in the population of Punjab (North-West India). The frequency of + 1059 G allele is highest in CAD (98.3%) followed by T2D (98.1%), T2D + CAD cases (97.7%) and controls (94.7%). G-allele is associated with increased risk of T2D [P = 0.003, OR = 2.93 (1.39–6.17)] and CAD [P = 0.004, OR = 3.25 (1.39–7.60)] in comparison to controls. Recessive model shows that GG genotype increases the risk of CAD by 4 fold (P = 0.003, OR = 4.19, 1.62–10.80), T2D by 3 fold (P = 0.008, OR = 3.23, 1.36–7.60) and T2D + CAD by 3.5 fold (P = 0.029, OR = 3.64, 1.14–11.66). Factor analyses show that BMI, WC, and WHR are core predictors for CAD and T2D, whereas CHO, TG and VLDL for T2D + CAD. The present study concludes that GG genotype of CRP + 1059 G>C polymorphism and clustering of obesity and dyslipidemia underlie the risk towards CAD, T2D and T2D + CAD in the North-West Indian population of Punjab.

Genomic diversity and affinities in population groups of North West India: An analysis of Alu insertion and a single nucleotide polymorphism

The North West region of India is extremely important to understand the peopling of India, as it acted as a corridor to the foreign invaders from Eurasia and Central Asia. A series of these invasions along with multiple migrations led to intermixture of variable populations, strongly contributing to genetic variations. The present investigation was designed to explore the genetic diversities and affinities among the five major ethnic groups from North West India; Brahmin, Jat Sikh, Bania, Rajput and Gujjar. A total of 327 individuals of the abovementioned ethnic groups were analyzed for 4 Alu insertion marker loci (ACE, PV92, APO and D1) and a Single Nucleotide Polymorphism (SNP) rs2234693 in the intronic region of the ESR1 gene. Statistical analysis was performed to interpret the genetic structure and diversity of the population groups. Genotypes for ACE, APO, ESR1 and PV92 loci were found to be in Hardy-Weinberg equilibrium in all the ethnic groups, while significant departures were observed at the D1 locus in every investigated population after Bonferronis correction. The average heterozygosity for all the loci in these ethnic groups was fairly substantial ranging from 0.3927 ± 0.1877 to 0.4333 ± 0.1416. Inbreeding coefficient indicated an overall 10% decrease in heterozygosity in these North West Indian populations. The gene differentiation among the populations was observed to be of the order of 0.013. Genetic distance estimates revealed that Gujjars were close to Banias and Jat Sikhs were close to Rajputs. Overall the study favored the recent division of the populations of North West India into largely endogamous groups. It was observed that the populations of North West India represent a more or less homogenous genetic entity, owing to their common ancestral history as well as geographical proximity.

Association of Transforming Growth Factor Beta-1 (TGF-β1) Genetic Variation with Type 2 Diabetes and End Stage Renal Disease in Two Large Population Samples from North India

Geographic and ethnic differences impart an immense influence on the genetic susceptibility to Type 2 diabetes (T2D) and diabetic nephropathy (DN). Transforming growth factor-beta1 (TGF-β1), a ubiquitously expressed pro-fibrotic cytokine plays a pivotal role in mediating the hypertrophic and fibrotic manifestations of DN. The present study is aimed to study the association of TGF-β1 g.869T>C (rs1800470) and g.-509C>T (rs1800469) polymorphism in T2D and end stage renal disease (ESRD) cases from the two geographically and ethnically different populations from North India. A total of 1313 samples comprising 776 samples from Punjab (204 with ESRD, 257 without ESRD, and 315 healthy controls) and 537 samples from Jammu and Kashmir (150 with ESRD, 187 without ESRD, and 200 controls) were genotyped for TGF-β1 (rs1800470 and rs1800469) using ARMS-PCR. The CC genotype of rs1800470 increased ESRD risk by 3.1-4.5-fold in both populations. However, for rs1800469, the TT genotype provided 5.5-fold risk towards ESRD cases from Jammu and Kashmir and no risk for the cases from Punjab. The haplotype C-T conferred nearly a 2-3-fold risk towards T2D and ESRD and diplotype CC-CT conferred a 4-fold risk towards ESRD. Our results conclude that TGF-β1 (rs1800470) may increase the risk of both ESRD and T2D in both populations, but TGF-β1 (rs1800469) provided risk for only ESRD in the population of Jammu and Kashmir. The present study is one of the large sample sized genetic association studies of T2D and ESRD from Indian population and adds to the scholarship on global health omics.

Association Study of Angiotensin-Converting Enzyme Ins/Del Polymorphism with Hypertension in Punjabi Population

Abstract Angiotensin-converting enzyme (ACE) is the key enzyme of the Renin-angiotensin system (RAS) which maintains the blood pressure homeostasis in our body. The association of the ACE insertion (I) or deletion (D) with essential hypertension has been demonstrated by many studies. The present study is aimed to determine the association, if any, of ACE I/D polymorphism with essential hypertension in Punjabi population. The ACE I/D polymorphism genotype frequencies were calculated by comparing essential hypertensive patients with ethnically similar normotensive controls. The samples were collected from the outpatient departments of various hospitals of Punjab. The subjects who had systolic blood pressure (SBP) of 140 mmHg or greater, and diastolic blood pressure (DBP) of 90 mmHg or greater, or were using any antihypertensive medication were considered as hypertensive. The DNA samples from the patients (100) and controls (100) were isolated, amplified by PCR and analyzed on agarose gel. When all the genotypes were compared in patients and controls, the chi square value was 0.444, which was not significant at 5% level. The age, height and weight were analyzed in the three different categories DD, ID, II which did not show any significant relationship with the disease. A consistent increase was seen in the SBP and DBP in all the three genotypes from DD, ID to II respectively. This increase was statistically significant for DBP especially in case of DD vs II at 5% level (t=2.34, p<0.05).

Association of genetic variants in INS (rs689), INSR (rs1799816) and PP1G.G (rs1799999) with type 2 diabetes (T2D): a case–control study in three ethnic groups from North-West India

Genetic contributions towards Type 2 diabetes (T2D) have been assessed through association studies across different world populations with inconsistencies. The majority of the T2D susceptibility loci are common across different races or populations but show ethnicity-specific differences. The pathogenesis of T2D involves genetic variants in the candidate genes. The interactions between the genes involved in insulin signaling and secretory pathways are believed to play an important role in determining an individual’s susceptibility towards T2D. Therefore, the present study was initiated to examine the differences, if any, in the contribution of polymorphisms towards T2D susceptibility in the background of different ethnic specifications. The present case–control study included a total of 1216 T2D cases and healthy controls from three ethnic groups (Jat Sikhs, Banias and Brahmins) of North-West India. Polymorphisms were selected on the basis of information available in the literature for INS (rs689), INSR (rs1799816) and PP1G.G (rs1799999) in context to T2D. The genotyping was done using PCR–RFLP method. Statistical analysis was done using SPSS 16.0. The analyses revealed that INS (rs689) polymorphism conferred risk towards T2D susceptibility in all the three ethnic groups whereas INSR (rs1799816) polymorphism conferred risk towards T2D in Brahmins only and PP1G.G (rs1799999) polymorphism indicated T2D risk in Jat Sikhs only. Furthermore, interaction analyses indicated the cumulative role of three genetic variants in modulating T2D susceptibility in the three ethnic groups. In conclusion, our results substantiated the evidences for the role of ethnicity in differential susceptibility to T2D in the background of same genetic variants.