K121Q ENPP1/PC-1 gene polymorphism is associated with insulin resistance in a North Indian population

Current Studies on Molecular Mechanisms of Insulin Resistance

Diabetes is a metabolic disease that raises the risk of microvascular and neurological disorders. Insensitivity to insulin is a characteristic of type II diabetes, which accounts for 85-90 percent of all diabetic patients. The fundamental molecular factor of insulin resistance may be impaired cell signal transduction mediated by the insulin receptor (IR). Several cell-signaling proteins, including IR, insulin receptor substrate (IRS), and phosphatidylinositol 3-kinase (PI3K), have been recognized as being important in the impaired insulin signaling pathway since they are associated with a large number of proteins that are strictly regulated and interact with other signaling pathways. Many studies have found a correlation between IR alternative splicing, IRS gene polymorphism, the complicated regulatory function of IRS serine/threonine phosphorylation, and the negative regulatory role of p85 in insulin resistance and diabetes mellitus. This review brings up-to-date knowledge of the roles of signaling proteins in insulin resistance in order to aid in the discovery of prospective targets for insulin resistance treatment.

Influence of Single Nucleotide Polymorphism of ENPP1 and ADIPOQ on Insulin Resistance and Obesity: A Case-Control Study in a Javanese Population

Single nucleotide polymorphisms (SNPs) in obesity-related genes, such as ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) and adiponectin (ADIPOQ), potentially increase the risk of insulin resistance, the most common metabolic dysregulation related to obesity. We investigated the association of ENPP1 SNP K121Q (rs1044498) with insulin resistance and ADIPOQ SNP + 267G > T (rs1501299) with circulating adiponectin levels in a case–control study involving 55 obese and 55 lean Javanese people residing in Yogyakarta, Indonesia. Allele frequency was determined by a chi squared test or Fisher’s exact test with an expected value less than 0.05. Odds ratios and 95% confidence intervals were estimated by regression logistic analysis. The presence of the Q121 allele of ENPP1 resulted in significantly higher fasting glucose, fasting insulin levels, and HOMA-IR, as compared to homozygous K121 carriers. The risk of insulin resistance was elevated in obese individuals carrying Q121 instead of homozygous K121. Adiponectin level was significantly lower in the obese group as compared to the lean group. Obese individuals carrying homozygous protective alleles (TT) of ADIPOQ tended to have lower adiponectin levels as compared to GT and GG carriers, however, we did not find statistically significant effects of the +276G > T SNP of the ADIPOQ gene on the plasma adiponectin levels or on the development of obesity.

Association of genetic polymorphism of PC-1 gene (rs1044498 Lys121Gln) with insulin-resistant type 2 diabetes mellitus in Punjabi Population of Pakistan

BACKGROUND

Insulin resistance (IR), known to reduce the response to insulin action, develops with obesity leading to type 2 diabetes mellitus (T2DM). The PC-1 gene has been associated with dyslipidemia, polycystic ovarian disease and T2DM in different regions of the world. The objective of the present study was to investigate the genetic association of PC-1 rs1044498 polymorphism with insulin resistance in type 2 diabetes in the Punjabi population of Pakistan.

METHODS

This study was carried out on 161 healthy controls and 161 patients of T2DM with insulin resistance. Whole blood was collected for DNA extraction and molecular studies. PCR-RFLP with AvaII was performed to determine the genotype in cases and controls. Chi-square and Hardy Weinberg analyses were carried out. Statistical analysis was performed by SPSS software.

RESULTS

The demographic data of cases and controls showed significant differences for different parameters like glucose, insulin, Homeostatic model assessment-insulin resistance (HOMA-IR) and lipid profiles (p < 0.000). Different statistical models revealed that all the dominant models were found associated in between alleles for disease risk (p < 0.001) while no association of PC-1 rs1044498 (K121Q) polymorphism was found with insulin-resistant parameters in T2DM cases.

CONCLUSION

Overall, the results indicate that the K121Q polymorphism was not found associated with insulin resistance in type 2 diabetes in a Pakistani Punjabi population. This is the first-ever report about the genotype of PC-1 gene in this population.

The Association of a Rare Variant of -93, -53 Promoter Gene Polymorphisms of Lipoprotein Lipase gene with Obesity and Insulin Resistance

Objectives

Obesity increases the risk of numerous chronic diseases. Obesity is classified clinically using body mass index (BMI), waist-to-hip ratio, and body fat percentage. The lipoprotein lipase (LPL) gene has been linked to lipoprotein metabolism and obesity. We performed a case-control study to determine the association between LPL gene polymorphisms and obesity-associated phenotypes such as insulin resistance (IR).

Methods

We examined the different LPL gene variants for association in 642 individuals segregated by BMI and IR. Genotyping of the LPL gene -93 and -53 promoter gene polymorphisms were analyzed using polymerase chain reaction-restriction fragment length polymorphism.

Results

A substantial association was observed for -93 gene polymorphism of the LPL gene with obesity, while -53 promoter gene polymorphism showed association with IR.

Conclusions

We found a significant association between -93 and -53 promoter gene polymorphisms of the LPL gene with obesity and associated phenotypes in the studied population.

New Insights Regarding Genetic Aspects of Childhood Obesity: A Minireview

Introduction: Childhood obesity is occurring at alarming rates in both developed and developing countries. "Obesogenic" environmental factors must be associated with variants of different risk alleles to determine polygenic or common obesity, and their impact depends on different developmental stages.The interaction between obesogenic environment and genetic susceptibility results in the so-called polygenic forms of obesity. In contrast, monogenic and syndromic obesity are not influenced by environmental events. Therefore, this review aimed to underline the roles of some of the most studied genes in the development of monogenic and polygenic obesity in children. Results: Among the most common obesity related genes, we chose the fat mass and obesity-associated (FTO) gene, leptin gene and its receptor, tumor necrosis factor alpha (TNF-α), the melanocortin 4 receptor gene (MC4R), Ectoenzyme nucleotide pyrophosphate phosphodiesterase 1 (ENPP1), and others, such as peroxisome proliferator-activated receptor gamma (PPARG), angiotensin-converting enzyme (ACE), glutathione S-transferase (GST), and interleukin-6 (IL-6) genes. The roles of these genes are complex and interdependent, being linked to different cornerstones in obesity development, such as appetite behavior, control of food intake and energy balance, insulin signaling, lipid and glucose metabolism, metabolic disorders, adipocyte differentiation, and so on. Conclusions: Genetic predisposition is mandatory, but not enough to trigger obesity.Dietary interventions and proper lifestyle changes can prevent obesity development in genetically predisposed children. Further studies are needed to identify the precise role of both genetic and obesogenic factors in the development of childhood obesity in order to design effective preventive methods.

The ENPP1 K121Q polymorphism modulates developing of bone disorders in type 2 diabetes: A cross sectional study

BACKGROUND

Osteoporosis and osteopenia are common diseases in every population. Type 2 diabetes mellitus (T2DM) can lead to the development of various complications, such as bone disorders especially among elderly individuals. Studies suggested that ectonucleotide pyrophosphatase/phosphodiesterase1 (ENPP1) is contributed in insulin resistance and also the inhibition of bone mineralization. In this study, association of K121Q (rs1044498) polymorphism of the ENPP1 gene with T2DM and bone disorders is evaluated.

METHODS

Four-hundred-and-ninety females who were classified based on bone mineral density (BMD) at lumbar spine and femur were included in this study. In addition, participants were classified according to their diabetes status. K121Q polymorphism was evaluated by the PCR-PFLF technique. One-way ANOVA was used for comparison of various analyzed factors in diseases subgroups and K121Q genotypes. Association of K121Q polymorphism with diabetes and bone disorders was evaluated by logistic regression.

RESULTS

Significant association was observed between K121Q polymorphism with osteoporosis and osteopenia (p=0.041, p=0.029, respectively), but a similar pattern was not observed in T2DM status (p=0.723). Moreover, in diabetic patients, K121Q polymorphism showed a better prediction potential for the development of bone disorders in comparison to non-diabetic subjects (p=0.018; OR=4.63, p=0.540; OR=1.31). There were no significant differences between K121Q genotypes with FBS, Ca, P, vitamin D, PTH and BMD status.

CONCLUSIONS

The present study implies that K121Q polymorphism of ENPP1 gene is able to modulate the development of bone disorders in T2DM. Therefore in diabetic patients screening of this polymorphism is suggested for the monitoring of these persons.

Common Genetic Variant of insig2 Gene rs7566605 Polymorphism Is Associated with Severe Obesity in North India

Background:

Obesity is a very common disorder resulting from an imbalance between food intake and energy expenditure, and it has a substantial impact on the development of chronic diseases. The aim of this study was to examine the association of INSIG2 (rs7566605) gene polymorphism with obesity and obesity associated phenotypes in North Indian subjects.

Methods:

The variants were investigated for association in 642 obese and non-obese individuals. The genotyping of INSIG2 (rs7566605) single nucleotide polymorphism was analyzed by the TaqMan allelic discrimination protocol.

Results:

A significant association was observed for INSIG2 (rs7566605) single nucleotide polymorphism with obesity and obesity-related phenotypes. Furthermore, a significant relationship was found between the rs7566605 and insulin, homeostasis model of assessment-insulin resistance, the percentage of body fat, fat mass, leptin, and adiponectin.

Conclusion:

The present study observed significant association between INSIG2 (rs7566605) single nucleotide polymorphism and obesity, as well as obesity-associated phenotypes in North Indian population.

The ENPP1 K121Q polymorphism is associated with type 2 diabetes and related metabolic phenotypes in a Taiwanese population

Increased risk of developing type 2 diabetes (T2D) has been associated with a single nucleotide polymorphism (SNP), rs1044498 (K121Q), in the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene, but this association is unclear among Asians. In this replication study, we reassessed whether the ENPP1 rs1044498 SNP is associated with T2D, obesity, and T2D/obesity-related metabolic traits in a Taiwanese population. A total of 1513 Taiwanese subjects were assessed in this study. The ENPP1 rs1044498 SNP was genotyped by the Taqman assay. T2D/Obesity-related quantitative traits, such as waist circumference and fasting glucose, were measured. Our data showed a significant association of the ENPP1 rs1044498 SNP with T2D (P < 0.001) among the subjects. Moreover, the ENPP1 rs1044498 SNP was significantly associated with T2D/obesity-related metabolic traits, such as waist circumference (P = 0.002) and fasting glucose (P < 0.001), among the subjects. However, we found no association of ENPP1 rs1044498 with obesity (BMI ≧ 27 kg/m(2)). Our study indicates that the ENPP1 rs1044498 SNP is associated with T2D, waist circumference, and fasting glucose in Taiwanese subjects.

Association of FTO rs9939609 SNP with Obesity and Obesity- Associated Phenotypes in a North Indian Population

OBJECTIVES

Obesity is a common disorder that has a significant impact on morbidity and mortality. Twin and adoption studies support the genetic influence on variation of obesity, and the estimates of the heritability of body mass index (BMI) is significantly high (30 to 70%). Variants in the fat mass and obesity-associated (FTO) gene have been associated with obesity and obesity-related phenotypes in different populations. The aim of this study was to examine the association of FTO rs9939609 with obesity and related phenotypes in North Indian subjects.  .

METHODS

Gene variants were investigated for association with obesity in 309 obese and 333 non-obese patients. Genotyping of the FTO rs9939609 single nucleotide polymorphism (SNP) was analyzed using Restriction Fragment Length Polymorphism Analysis of PCR-Amplified Fragments. We also measured participants fasting glucose and insulin levels, lipid profile, percentage body fat, fat mass and fat free mass.  .

RESULTS

Waist to hip ratio, systolic blood pressure, diastolic blood pressure, percentage body fat, fat mass, insulin concentration, and homeostasis model assessment index (HOMA-Index) showed a significant difference between the study groups. Significant associations were found for FTO rs9939609 SNP with obesity and obesity-related phenotypes. The significant associations were observed between the rs9939609 SNP and blood pressure, fat mass, insulin, and HOMA-index under a different model.  .

CONCLUSION

This study presents significant association between FTO rs9939609 and obesity defined by BMI and also established the strong association with several measures of obesity in North Indian population.

Association of adiponectin gene polymorphism with adiponectin levels and risk for insulin resistance syndrome

Background:

Adiponectin is an abundant adipose tissue–derived protein with anti-atherogenic, anti-inflammatory and antidiabetic properties. Plasma adiponectin levels are decreased in obesity, type 2 diabetes, and coronary artery disease and low adiponectin levels also predict insulin resistance (IR).

Methods:

Case-control study in which 642 male and female subjects were participated from the North Indian population. Lipid, insulin, leptin and adiponectin level were estimated using standard protocols by commercially available test kits. Single nucleotide polymorphisms +45T>G and +276G>T of the AMP1 (adiponectin) gene was genotyped by polymerase chain reaction restriction fragment length polymorphism method.

Results:

Levels of adiponectin, insulin, homeostasis model assessment-IR index (HOMA-IR index), systolic blood pressure and fat mass showed significant differences between male and female subjects. Serum adiponectin level showed highly significant association with both the +45 and the +276 genotypes. The common haplotype triglyceride (TG) showed a significantly lower adiponectin value than other haplotypes (P = 0.0001). A clear trend of decreasing adiponectin levels per copy of the common haplotype was observed. Nonobese insulin sensitive subjects showed a higher adiponectin value (P = 0.0006) than nonobese insulin resistant subjects. The values of blood pressure, adiponectin, insulin, HOMA-IR, total-cholesterol, and low-density lipoprotein-cholesterol significantly associated with TG haplotype.

Conclusions:

We observed the very strong association of the adiponectin 45-276 genotypes and haplotypes with adiponectin levels in healthy north Indian population and TG haplotypes also associated with metabolic parameters of the IR syndrome.