Evaluation of the association between retinal binding protein 4 polymorphisms and type 2 diabetes in Chinese by DHPLC

GHRL Gene Leu72Met Polymorphism and Type 2 Diabetes Mellitus: A Meta-Analysis Involving 8,194 Participants

Background: Although many studies indicate a positive correlation between GHRL gene Leu72Met polymorphism and an increased susceptibility to type 2 diabetes mellitus (T2DM), inconsistencies between independent studies still remain. Objective: Considering the inconsistencies between them, we have performed the current meta-analysis study. The objective of this study is to better examine the correlation of the GHRL gene Leu72Met polymorphism and T2DM. Methods: The current meta-analysis, involving 8,194 participants from 11 independent studies, was performed. A fixed effect model was used to evaluate the pooled odds ratios (ORs) and the corresponding 95% confidence intervals (95% CIs). Results: A significant association was found between T2DM and GHRL gene Leu72Met polymorphism under recessive (OR: 1.33, 95% CI: 1.01-1.76, P = 0.04), and homozygous genetic models (OR: 1.34, 95% CI: 1.01-1.78, P = 0.04) in the whole population. The correlation was more distinct in our subgroup analysis of the Chinese population under recessive (OR: 1.52, 95% CI: 1.07-2.15, P = 0.02), dominant (OR: 1.70, 95% CI: 1.38-2.10, P < 0.00001), additive (OR: 1.16, 95% CI: 1.02-1.33, P = 0.02), and homozygous genetic models (OR: 1.54, 95% CI: 1.07-2.20, P = 0.02). Conclusions: In short, GHRL gene Leu72Met polymorphism was significantly correlated with increased T2DM risk, particularly in the Chinese population. Individuals carrying the Met72 allele of GHRL Leu72Met gene polymorphism, particularly those of Chinese ancestry, may be more susceptible to developing T2DM disease.

Serum level and polymorphisms of retinol-binding protein-4 and risk for gestational diabetes mellitus: a meta-analysis

BACKGROUND

Retinol-binding protein-4 (RBP4) has been reported to be potentially involved in the pathogenesis of gestational diabetes mellitus (GDM); however, the findings are inconsistent. Our aims were to review the studies that investigated the association of serum levels and polymorphisms of RBP4 with GDM risk, and to provide recommendations for future research.

METHODS

The databases PubMed, EBSCO, ScienceDirect, and Web of Knowledge were searched up to October 2015 to find out studies evaluating the relationship between serum RBP4 level/ RBP4 polymorphisms and GDM risk. In the meta-analysis of serum RBP4 levels the key inclusion was that studies were designed as BMI-matched studies or had observed non-significant differences in BMI between cases and controls.

RESULTS

Fourteen case-control studies (647 cases and 620 controls) reporting the association between serum RBP4 level and GDM risk, and three studies (1012 cases and 1605 controls) investigating the association between RBP4 polymorphisms and GDM risk were involved. Our results showed that high serum RBP4 levels represent a risk factor for GDM (pooled standardized mean difference =0.758, 95% confidence interval [0.387, 1.128]). The results of subgroup analyses based on "gestational age at blood sampling" or "diagnostic criteria" are consistent with the overall results. However, the postpartum subgroup and "before 24 weeks" subgroup both only include one article and indicate no association between serum RBP4 level and GDM risk. The meta-analysis on the association between rs3758539 polymorphism and GDM risk shows that RBP4 rs3758539 polymorphism is not associated with the development of GDM.

CONCLUSIONS

The results of this meta-analysis support the hypothesis that RBP4 is a modest independent risk factor for GDM (i.e., nonobese patients with GDM might express RBP4 at abnormal levels). The serum RBP4 level is associated with the risk of GDM. However, the association in the first-trimester and postpartum period should be validated by further research. The association between RBP4 rs3758539 polymorphism and GDM risk was not confirmed.

Association of P213S polymorphism of the L-selectin gene with type 2 diabetes and insulin resistance in Chinese population

AIMS

L-selectin belongs to selectin family of adhesion molecule and participates in the generation and development of type 2 diabetes (T2D). In this study, we evaluated the relationship between the P213S polymorphism of L-selectin gene and T2D and insulin resistance in the Chinese population.

METHODS

We genotyped P213S polymorphism in 801 patients with T2D and 834 healthy controls in the Chinese population using polymerase chain reaction-ligase detection reaction (PCR-LDR) technique. Plasma glucose, insulin, lipid, blood urea nitrogen, creatinine and uric acid levels were measured by biochemical technique.

RESULTS

The frequency of 213PP genotype and P allele of the L-selectin gene in patients with T2D was significantly higher than that in controls (P=0.007; P=0.019, respectively). The relative risk of allele P suffered from T2D was 1.191 times higher than that of allele S. Moreover, the levels of FPG and HOMA-IR of PP and PS genotype carriers were significantly higher than those of SS genotype carriers in the T2D group (P<0.05).

CONCLUSION

These findings indicated that the P213S polymorphism of L-selectin gene may contribute to susceptibility to T2D and insulin resistance in the Chinese population, and P allele appears to be a risk factor for T2D.

Association of RBP4 gene variants and serum HDL cholesterol levels in the Newfoundland population

Retinol-binding protein 4 (RBP4) is a novel adipokine that likely contributes to systemic insulin resistance and dyslipidemia. The role of genetic variations in RBP4 on phenotypes of glucose and lipid metabolism is not clear in humans. The purpose of this study was to examine five single-nucleotide polymorphisms (SNPs) in the RBP4 gene to determine their relationship with markers of insulin resistance and serum lipids in the CODING Study. The CODING Study consists of 1,836 subjects recruited from the genetically homogeneous population of Newfoundland and Labrador (NL), Canada. Serum glucose, insulin, homeostasis model assessment of insulin resistance (HOMA(IR)), HOMA for beta cell function (HOMA(beta)), total cholesterol (Chol), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides were determined after a 12-h fast. Five SNPs within RBP4 (rs3758539, G/A 5' flanking region; rs61461737, A/G intron; rs10882280, C/A intron; rs11187545, A/G intron; and rs12265684, C/G intron) were genotyped using TaqMan validated or functionally tested SNP genotyping assays. After correcting for multiple testing, we observed a significant association between the minor allele of two noncoding SNPs (rs10882280 and rs11187545) and higher serum HDL-C (P = 0.043 and 0.042, respectively). No significant associations were observed with any other parameter related to lipid metabolism. We also found no significant association between any variant sites and markers of insulin resistance. Our results suggest that genetic variations in RBP4 may play a role in the differences in serum HDL-C levels in the NL population.