ENPP1/PC-1 K121Q polymorphism and genetic susceptibility to type 2 diabetes in North Indians

Phenotypic clusters of type 2 diabetes mellitus among North Indians reveal higher levels of insulin deficiency along with insulin resistance

BACKGROUND

Type 2 diabetes is now considered a heterogenous disease. Distinct clusters have been identified with patterns varying between Europeans and South Asians as well as between South Indians who have described a novel cluster; Combined Insulin-Resistant and Deficient Diabetes, and individuals from West and East India who have reported that insulin deficiency is the primary driver of heterogeneity. Therefore, North Indian patients may also have a distinct, novel clustering pattern due to unique genetic, epigenetic, and environmental factors. We aim to identify clusters of type 2 diabetes in North Indians and to describe the different characteristics of these clusters.

METHODS

The K value for the optimal number of clusters was obtained from two-step clustering. K means clustering was done with this K value using SPSS 29.0 software. Variables used for clustering were age, BMI, HbA1c, HOMA-beta, HOMA-IR, and waist circumference.

RESULTS

Four phenotypically different clusters were identified in 469 individuals with type 2 diabetes. Cluster 1 was severe insulin deficient diabetes (15%), Cluster 2 was severe insulin resistant diabetes (22%), Cluster 3 was moderate obesity-related diabetes (35%), and Cluster 4 was moderate age-related diabetes (27%). Clusters 1 and 2 were similar to earlier studies but in different proportions. Clusters 3 and 4 characteristics were different from earlier studies, with greater impairment in beta cell function and higher HbA1c levels. Significant insulin resistance was noted in all clusters.

CONCLUSION

The phenotypic clusters of type 2 diabetes identified in the present study were characterized by high levels of insulin deficiency along with important contributions from insulin resistance.

Pharmacogenomics and Personalized Medicine in Type 2 Diabetes Mellitus: Potential Implications for Clinical Practice

Type 2 diabetes mellitus (T2DM) is the most common form of diabetes, and is rising in incidence with widespread prevalence. Multiple gene variants are associated with glucose homeostasis, complex T2DM pathogenesis, and its complications. Exploring more effective therapeutic strategies for patients with diabetes is crucial. Pharmacogenomics has made precision medicine possible by allowing for individualized drug therapy based on a patient's genetic and genomic information. T2DM is treated with various classes of oral hypoglycemic agents, such as biguanides, sulfonylureas, thiazolidinediones, meglitinides, DPP4 inhibitors, SGLT2 inhibitors, α-glucosidase inhibitors, and GLP1 analogues, which exhibit various pharmacogenetic variants. Although genomic interventions in monogenic diabetes have been implemented in clinical practice, they are still in the early stages for complex polygenic disorders, such as T2DM. Precision DM medicine has the potential to be effective in personalized therapy for those suffering from various forms of DM, such as T2DM. With recent developments in genetic techniques, the application of candidate-gene studies, large-scale genotyping investigations, genome-wide association studies, and "multiomics" studies has begun to produce results that may lead to changes in clinical practice. Enhanced knowledge of the genetic architecture of T2DM presents a bigger translational potential. This review summarizes the genetics and pathophysiology of T2DM, candidate-gene approaches, genome-wide association studies, personalized medicine, clinical relevance of pharmacogenetic variants associated with oral hypoglycemic agents, and paths toward personalized diabetology.

Association of the ENPP1/ENTPD1 Polymorphisms in Hemodialysis Patients

Introduction

ENPP1 and ENTPD1 are two main enzymes involved in ATP-AMP-ADP-adenosine axis, which is associated with lipid metabolism, diabetes mellitus (DM) and renal fibrosis. The single nucleotide polymorphisms (SNPs) of ENPP1 and ENTPD1, rs1044498 and rs6584026, are associated with these factors. This retrospective study aimed to address the two SNPs variants in hemodialysis (HD) patients and analyzes their relations with clinical characteristics.

Methods

This study included 543 regular HD patients over 3 months at our center. Overnight fasting peripheral blood sample was taken from each subject to extract the DNA. The genotypes of rs1044498 and rs6584026 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The basic clinical data were noted such as sex, age, and HD-age, and the main causes of chronic kidney disease (CKD) and the clinical characteristics were collected on average at least three times in half a year. T-test and Chi-test were performed for the statistical analyses. Binary logistic regression was applied for the significant parameters by excluding the confounders, gender, age and HD-age. All statistical tests were considered significant for P<0.05.

Results

The rs1044498 genotypes showed in two types, A/A and A/C without C/C. The rs6584026 genotypes were C/C and C/T without T/T. The genotype frequency of rs1044498 (A/C) was 0.238, and the genotype frequency of rs6584026 (C/T) was 0.328. The age and the level of lipoprotein α showed statistical significance with rs1044498 variant (A/C, P<0.05). The rs6584026 variant (C/T) was frequently found in patients with nephritis (P<0.05). The albumin, alkaline phosphatase (ALP), lipoprotein α, cholesterol, apolipoprotein B (Apo B), Apo B/A1 and nephritis were independently associated with rs6584026 variant (C/T, P<0.05) in binary logistic regression model by controlling the confounders of gender, age and HD-age. High level of triglyceride and low level of urine nitrogen were related to rs6584026 variant (C/T, P<0.05).

Conclusion

The rs1044498 and rs6584026 SNPs were related to several high levels of lipids, and rs6584026 variant was related to nephritis and autoimmune disease. The rs6584026 SNP may contribute to the increased risks of cholesterol and ApoB/A1 in HD patients.

A review on interplay between obesity, lipoprotein profile and nutrigenetics with selected candidate marker genes of type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus, a rapidly growing epidemic, and its frequently related complications demand global attention. The two factors commonly attributed to the epidemic are genetic factors and environmental factors. Studies indicate that the genetic makeup at an individual level and the environmental aspects influence the occurrence of the disease. However, there is insufficiency in understanding the mechanisms through which the gene mutations and environmental components individually lead to T2DM. Also, discrepancies have often been noted in the association of gene variants and type 2 diabetes when the gene factor is examined as a sole attribute to the disease.

STUDY

In this review initially, we have focused on the proposed ways through which CAPN10, FABP2, GLUT2, TCF7L2, and ENPP1 variants lead to T2DM along with the inconsistencies observed in the gene-disease association. The article also emphasizes on obesity, lipoprotein profile, and nutrition as environmental factors and how they lead to T2DM. Finally, the main objective is explored, the environment-gene-disease association i.e. the influence of each environmental factor on the aforementioned specific gene-T2DM relationship to understand if the disease-causing capability of the gene variants is exacerbated by environmental influences.

CONCLUSION

We found that environmental factors may influence the gene-disease relationship. Reciprocally, the genetic factors may alter the environment-disease relationship. To precisely conclude that the two factors act synergistically to lead to T2DM, more attention has to be paid to the combined influence of the genetic variants and environmental factors on T2DM occurrence instead of studying the influence of the factors separately.

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.

ENPP1 in the Regulation of Mineralization and Beyond

ENPP1 is well known for its role in regulating skeletal and soft tissue mineralization. It primarily exerts its function through the generation of pyrophosphate, a key inhibitor of hydroxyapatite formation. Several previous studies have suggested that ENPP1 also contributes to a range of human diseases including diabetes, cancer, cardiovascular disease, and osteoarthritis. In this review, we summarize the pathological roles of ENPP1 in mineralization and these soft tissue disorders. We also discuss the underlying mechanisms through which ENPP1 exerts its pathological effects. A fuller understanding of the pathways through which ENPP1 acts may help to develop novel therapeutic strategies for these commonly diagnosed morbidities.

Association and in silico studies of ENPP1 gene variants with type 2 diabetes mellitus in a Northern Iranian population

In the current study, a sample population of Northern Iranians was selected to investigate the association of K121Q, rs1799774, rs7754561, and rs997509 ENPP1 gene variants and their haplotypes with T2DM. Genomic DNAs of 978 samples were extracted by Salting Out standard technique and then genotyped by the TaqMan assay. The results show significant differences between study groups for K121Q (p = 0.0004) under a Dominant and rs7754561 (p = 0.002) under a co-dominant hereditary model. Based on allele frequency, there was a significant difference between two study groups at K121Q and rs7754561 variants (p = 0.010 and p = 0.01, respectively). There was no evidence for an association between ENPP1 haplotypes and overall risk of T2DM. Genotype-phenotype sub-analyses showed no significant relationship of four studied polymorphisms with age, gender, FBS, and systolic and diastolic blood pressures. Homology modeling and molecular docking of ENPP1 in K173 and Q173 models with ATP, AMP, and 2'3'-cGAMP as ligands revealed that all ligands had a more binding affinity to Lys173 protein model, and 2'3'-cGAMP had a higher affinity to both ENPP1 protein models compared to ATP and AMP. These findings suggest that ENPP1 gene variants may have a potential impact on the occurrence of T2DM in Northern Iranians.

ENPP1 121Q functional variant enhances susceptibility to coronary artery disease in South Indian patients with type 2 diabetes mellitus

Insulin resistance is associated with endothelial dysfunction and ensuing cardiovascular diseases in type 2 diabetes mellitus (T2DM) patients. ENPP1 is a key modulator of insulin signaling and its polymorphism, K121Q, increases the potency to competitively inhibit insulin receptor binding. We investigated the association of ENPP1 121Q variant with coronary artery disease (CAD) in patients with and without T2DM in South Indian population. Our study was conducted in 913 subjects: 198 patients with CAD, 284 patients in whom T2DM and CAD co-exists, 160 patients with T2DM and no CAD history, and 271 healthy volunteers. Genotyping was performed using PCR-RFLP and PCR-DNA sequencing. Genotype frequency of ENPP1 121Q was higher in disease groups compared to healthy subjects (p < 0.05). T2DM patients who carried polymorphic AC/CC genotypes were at 12.8-fold enhanced risk to CAD (95% CI 4.97-37.18, p < 0.01). Moreover we observed that 121Q, both in heterozygous and homozygous polymorphic states, was a risk factor for CAD without diabetes (OR 4.15, p < 0.01). 121Q variant was associated with T2DM patients with no CAD history too, but the risk was statistically insignificant after multivariate logistic regression analysis (OR 2.32, p > 0.05). We conclude that ENPP1 121Q variant is associated with increased risk for CAD in patients with T2DM in South Indian population. We also report that 121Q variant of ENPP1 was an independent risk factor for CAD irrespective of diabetic milieu. Factors which enhance insulin resistance increase the risk for onset and progression of coronary atherosclerosis irrespective of a diabetic background.

Therapeutic Strategies for Mitochondrial Dysfunction and Oxidative Stress in Age-Related Metabolic Disorders

Mitochondria are complex, intercellular organelles present in the cells and are involved in multiple roles including ATP formation, free radicals generation and scavenging, calcium homeostasis, cellular differentiation, and cell death. Many studies depicted the involvement of mitochondrial dysfunction and oxidative damage in aging and pathogenesis of age-related metabolic disorders and neurodegenerative diseases. Remarkable advancements have been made in understanding the structure, function, and physiology of mitochondria in metabolic disorders such as diabetes, obesity, cardiovascular diseases, and stroke. Further, much progress has been done in the improvement of therapeutic strategies, including lifestyle interventions, pharmacological, and mitochondria-targeted therapeutic approaches. These strategies were mainly focused to reduce the mitochondrial dysfunction caused by oxidative stress and to retain the mitochondrial health in various diseases. In this chapter, we have highlighted the involvement of mitochondrial dysfunction in the pathophysiology of various disorders and recent progress in the development of mitochondria-targeted molecules as therapeutic measures for metabolic disorders.

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.

Implications of ACE (I/D) Gene Variants to the Genetic Susceptibility of Coronary Artery Disease in Asian Indians

Angiotensin-1-converting enzyme (ACE) gene has established substantial attention in the recent years as a candidate gene for hypertension, cardiovascular diseases and type 2 diabetes. The aim of the present study was to investigate the association of ACE (I/D) polymorphism with coronary artery disease (CAD) in a north Indian population. A total of 662 subjects (330 CAD patients and 332 healthy controls) were examined for association of ACE gene (I/D) polymorphism and environmental risk factors. The mean age of the CAD patients and control subjects was 60.53 ± 8.6 years and 56.55 ± 7.7 years, respectively (p = 0.000). Anthropometric and demographic data showed BMI values significantly higher among CAD patients and control subjects (26.98 ± 4.9 vs 24.04 ± 4.7, p = 0.000). We observed pronounced central obesity in both CAD patients and controls, even at the lowest BMI values (<23 kg/m²). Dyslipidemia was highly prevalent in CAD patients compared to control subjects. Genotypic data showed significantly higher frequency of DD genotype in CAD patients than that of control subjects (40 vs 28.3 %). No significant difference was observed in the distribution of ID genotypes between CAD patients and control subjects. Logistic regression analysis of data demonstrate that DD genotype was associated with 1.8 fold increased risk of development of CAD in Asian Indians (OR 1.8; 95 % CI 1.22-2.66; p = 0.003). The frequency of D allele was significantly higher in CAD patients (p = 0.001). No significant difference was observed in the clinical and biochemical characteristics of CAD patients and controls when the data was stratified according to the genotypes of ACE gene. In conclusion, DD genotype of ACE gene may be associated with increased risk of CAD in Asian Indian population.

Meta-analysis of association studies between five candidate genes and type 2 diabetes in Chinese Han population

The multiple small-scale association studies of candidate genes for type 2 diabetes mellitus in the Chinese Han population have shown inconsistent results. Here, we performed a meta-analysis to evaluate the contribution of five candidate genes to the pathogenesis of type 2 diabetes in the Chinese Han population. We searched for relevant published papers and used STATA v.11.0 to perform a meta-analysis on six single-nucleotide polymorphisms in five genes-ADIPOQ-rs2241766 (SNP45) and -rs1501299 (SNP276), ADRB3-rs4994 (Trp64Arg), CAPN10-rs3792267 (SNP43), ENPP1-rs1044498 (K121Q), and PPARGC1A-rs8192678 (Gly482Ser)-in the Chinese Han population under an additive genetic model. The pooled odds ratios (95% confidence intervals and P-values) were 0.71 (0.60-0.83; P < 0.001) for ADIPOQ-rs2241766, 0.79 (0.64-0.97; P = 0.027) for ADIPOQ-rs1501299, 1.27 (1.07-1.51; P = 0.006) for ADRB3-rs4994, 0.79 (0.57-1.10; P = 0.163) for CAPN10-rs3792267, 1.41 (1.13-1.76; P = 0.003) for ENPP1-rs1044498, and 1.54 (1.34-1.81; P < 0.001) for PPARGC1A-rs8192678. There was high heterogeneity for ADIPOQ-rs2241766, ADIPOQ-rs1501299, and CAPN10-rs3792267 (I² = 74.9, 69.4, and 75.8%, respectively), but not for ADRB3-rs4994, ENPP1-rs1044498, and PPARGC1A-rs8192678 (I² = 0.0, 43.4, and 23.3%, respectively). Under an additive genetic model, the C allele of ADRB3-rs4994, the C allele of ENPP1-rs1044498, and the A allele of PPARGC1A-rs8192678 increase the risk of type 2 diabetes in the Chinese Han population.

Contribution of common variants of ENPP1, IGF2BP2, KCNJ11, MLXIPL, PPARγ, SLC30A8 and TCF7L2 to the risk of type 2 diabetes in Lebanese and Tunisian Arabs

BACKGROUND

While several type 2 diabetes mellitus (T2DM) susceptibility loci identified through genome-wide association studies (GWAS) have been replicated in many populations, their association in Arabs has not been reported. For this reason, the present study looked at the contribution of ENNP1 (rs1044498), IGF2BP2 (rs1470579), KCNJ11 (rs5219), MLXIPL (rs7800944), PPARγ (rs1801282), SLC30A8 (rs13266634) and TCF7L2 (rs7903146) SNPs to the risk of T2DM in Lebanese and Tunisian Arabs.

METHODS

Study subjects (case/controls) were Lebanese (751/918) and Tunisians (1470/838). Genotyping was carried out by the allelic discrimination method.

RESULTS

In Lebanese and Tunisians, neither ENNP1 nor MLXIPL was associated with T2DM, whereas TCF7L2 was significantly associated with an increased risk of T2DM in both the Lebanese [P < 0.001; OR (95% CI): 1.38 (1.20-1.59)] and Tunisians [P < 0.001; OR (95% CI): 1.36 (1.18-1.56)]. Differential associations of IGF2BP2, KCNJ11, PPARγ and SLC30A8 with T2DM were noted in the two populations. IGF2BP2 [P = 1.3 × 10(-5); OR (95% CI): 1.66 (1.42-1.94)] and PPARγ [P = 0.005; OR (95% CI): 1.41 (1.10-1.80)] were associated with T2DM in the Lebanese, but not Tunisians, while KCNJ11 [P = 8.0 × 10(-4); OR (95% CI): 1.27 (1.09-1.47)] and SLC30A8 [P = 1.6 × 10(-5); OR (95% CI): 1.37 (1.15-1.62)] were associated with T2DM in the Tunisians, but not Lebanese, after adjusting for gender and body mass index.

CONCLUSION

T2DM susceptibility loci SNPs identified through GWAS showed differential associations with T2DM in two Arab populations, thus further confirming the ethnic contributions of these variants to T2DM susceptibility.

ENPP1 K121Q polymorphism and type 2 diabetes mellitus in the Chinese population: a meta-analysis including 11,855 subjects

Ectoenzyme nucleotide pyrophosphate phosphodiesterase 1 (ENPP1) K121Q gene polymorphism has been suggested to be associated with the increased risk of developing type 2 diabetes mellitus (T2D), but relevant research results are still contradictory. To explore the relationship between ENPP1 K121Q gene polymorphism and T2D in the Chinese population, a meta-analysis was performed. Fourteen independent studies involving 11 855 subjects were retrieved from electronic databases. The pooled odds ratio (ORs) for the distribution of Q allele frequency of the ENPP1 K121Q gene and its corresponding 95% confidence interval (95% CI) were assessed using a random-effects model. Under an allelic model of inheritance, the distribution of Q allele frequency was 0.107 for the T2D group and 0.093 for the control group. The pooled OR for the distribution of Q allele frequency of ENPP1 K121Q gene was 1.29 (95% CI, 1.09-1.53; P(heterogeneity) = .006; I(2) = 55.6%). There was a significant association between ENPP1 K121Q gene polymorphism and T2D in the Chinese population (P = .003). Under a dominant model of inheritance, the KQ + QQ/KK value was 0.259 for the T2D group and 0.220 for the control group. The pooled OR for the KQ + QQ/KK value was 1.51 (95% CI, 1.20-1.91; P(heterogeneity) < .0001; I(2) = 71.8%). The association between ENPP1 K121Q gene polymorphism and T2D in the Chinese population followed a dominant model of inheritance (P = .0005). In the Chinese population, the ENPP1 K121Q gene polymorphism was implied to be involved with T2D susceptibility. People with the Q allele of the ENPP1 K121Q gene might be predisposed to T2D.

DIABETES MELLITUS: ENQUIRY INTO ITS MEDICAL ASPECTS AND BIOENGINEERING OF ITS MONITORING AND REGULATION

Diabetes mellitus (DM) or hyperglycemia (in a more generalized term, high blood sugar) is a metabolic disorder that is now highly prevalent in the world population. Most of the food that people consume is converted into glucose, which enters the bloodstream following absorption–assimilation mechanisms. As a natural process, cells in our body utilize glucose for growth and energy. The glucose balance is maintained by a hormone called insulin that is secreted by the beta cells of pancreas. Hypotheses at the backdrop of DM occurrence are either (i) enough insulin is not produced and secreted resulting in increased level of glucose in blood, or (ii) insulin is insensitive to glucose, or (iii) insulin is non-targeted etc. If DM remains uncontrolled over time, it leads to serious damage to many of the body's systems, especially the nerves and blood vessels. This paper develops an enquiry into diabetes from many angles: (i) Diabetes as a disorder, its complications, causes, diagnostic tests, and treatment; (ii) Analysis of retinal and plantar images to characterize diabetes complications; (iii) How analysis of heart rate variability signals can depict diabetes; (iv) Biomedical engineering of the glucose–insulin regulatory system, and its employment in the modeling of the oral glucose tolerance test data, to detect diabetes as well as persons at risk of being diabetic; (v) Application of the glucose–insulin regulatory system to formulate an insulin delivery system for controlling blood sugar.

Amerindians show no association of PC-1 gene Gln121 allele and obesity: a thrifty gene population genetics

PC-1 Gln121 gene is a risk factor for type 2 diabetes, obesity and insulin resistance in European/American Caucasoids and Orientals. We have aimed to correlate for the first time this gene in Amerindians with obesity and their corresponding individuals genotypes with obesity in order to establish preventive medicine programs for this population and also studying the evolution of gene frequencies in world populations. Central obesity was diagnosed by waist circumference perimeter and food intake independent HDL-cholesterol plasma levels were measured. HLA genes were determined in order to more objectively ascertain participants Amerindians origin. 321 Amerindian blood donors who were healthy according to the blood doning parameters were studied. No association was found between PC-1 Gln121 variant and obesity. Significant HDL-cholesterol lower values were found in the PC-1 Lys121 bearing gene individuals versus PC-1 Gln121 bearing gene ones (45.1 ± 12.7 vs. 48.7 ± 15.2 mg/dl, p < 0.05). Population analyses showed a world geographical gradient in the PC-1 Gln121 allele frequency: around 9% in Orientals, 15% in European Caucasoids and 76% in Negroids. The conclusions are: (1) No association of PC-1 Gln121 gene is found with obesity in Amerindians when association is well established in Europeans. (2) PC-1 Gln121 gene is associated to higher levels of HDL-cholesterol than the alternative PC-1 Lys121 allele. This may be specific for Amerindians. (3) Amerindians have an intermediate frequency of this possible PC-1 Gln121 thrifty gene when compared with Negroid African Americans (78.5%) or Han Chinese (7.5%, p < 0.0001). Historical details of African and other groups may support the hypothesis that PC-1 Gln121 is indeed a thrifty gene.

The ENPP1 K121Q polymorphism is not associated with type 2 diabetes in northern Chinese

The K121Q polymorphism of the ectoenzyme nucleotide pyrophosphate phosphodiesterase 1 (ENPP1) gene has been studied in relation to insulin resistance, type 2 diabetes, and obesity, and conflicting results were observed in various populations. The purpose of the present study was to investigate the prevalence of K121Q polymorphism of ENPP1 gene and to clarify whether this polymorphism is associated with type 2 diabetes susceptibility in northern Chinese population. We studied the association of the ENPP1 K121Q polymorphism with type 2 diabetes (T2D) in 639 unrelated patients and 885 control subjects with normal glucose tolerance of northern China. The patients were diagnosed in accordance with the guidelines of the American Diabetes Association (ADA). Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The distribution of KK, KQ, and QQ genotypes among patients was 79.5, 19.2, and 1.3%, similar to that of the control group (79.2, 20.1, and 0.7%). After readjusting for the confounding effects of age, gender, and BMI, no significant effect of genotypes on T2D was found for any of the genetic models tested (recessive model, dominant model, or additive model). All clinical characteristics tested were similar among the different genotypes, and no significant associations were observed both in T2D patients and in controls. When subgroup analyses of T2D patients and non-diabetic controls were stratified according to BMI and waist circumference, the variant was still not associated with T2D. The results showed that the ENPP1 K121Q polymorphism is not associated with genetic susceptibility of type 2 diabetes in the northern Chinese population.