Lack of association of the Ala45Thr variant in the BETA2/NEUROD1 with type 1 diabetes in Japanese

Neuronal Differentiation 1 gene Ala45Thr polymorphism and type 2 diabetes mellitus: A meta-analysis of 7,940 subjects

BACKGROUND AND AIMS

Previous studies have shown that there was a possible relationship between human Neuronal Differentiation 1 (NEUROD1) gene Ala45Thr polymorphism and type 2 diabetes mellitus (T2DM) susceptibility. Nevertheless, no public opinion has been formed because of the conflicting results in the past studies. In order to illuminate the potential association of human NEUROD1 gene Ala45Thr polymorphism and T2DM, the present meta-analysis was conducted.

METHODS AND RESULTS

In the current meta-analysis, 7940 subjects from 14 individual studies were included. The fixed or random effects models were used to evaluate the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs). The current meta-analysis found a significant association between NEUROD1 gene Ala45Thr polymorphism and T2DM under allelic (OR: 1.21, 95% CI: 1.04-1.41, P = 0.01), dominant (OR: 0.819, 95% CI: 0.734-0.913, P = 3.31 × 10^-4), heterozygous (OR:1.199, 95% CI: 1.068-1.346, P = 0.002), and additive (OR: 1.33, 95% CI: 1.09-1.62, P = 0.004) genetic models.

CONCLUSIONS

NEUROD1 gene Ala45Thr polymorphism was significantly related to T2DM, especially in the Asian population. More particularly, the Thr45 allele carriers of the NEUROD1 gene may be more susceptible to T2DM.

Evaluation of variant A45T in NEUROD1/BETA2 for its association with type 2 diabetes mellitus

Heterozygous loss-of-function mutations in NEUROD1 have been identified as a very rare cause of maturity-onset diabetes of the young and neonatal diabetes. Previous studies showed that a common A45T variant located in NEUROD1 was inconsistently associated with type 2 diabetes mellitus (T2DM) in different ethnic populations. This study aimed to evaluate the contribution of variant A45T in the genetic pathogenesis of T2DM. A case-control study in a Chinese Han population was conducted, which included 3,554 (1,155 males/2,399 females) patients with T2DM and 4,181 (1,798 males/2,383 females) control subjects from 13 different regions of China. The A45T variant was genotyped by the Illumina GoldenGate platform. A meta-analysis was used to estimate the effects of variant A45T in populations from different ethnic backgrounds. No association in Chinese Han subjects was confirmed in our case control study. A relationship between variant A45T and postprandial glucose was observed in the control group (β = 0.05, p = 0.002). Meta-analyses did not find an association of this polymorphism with T2DM in Chinese, Japanese, and East Asian descent, but did for European descent Caucasians (odds ratio = 1.15, 95 %CI 1.03-1.28, p = 0.01). Our study suggests the variant A45T does not play a major role in the development of T2DM in East Asian descent, and the role in European descent Caucasian needs to be confirmed.

Ala45Thr variation in neuroD1 gene is associated with early-onset type 2 diabetes with or without diabetic pedigree in Chinese

OBJECTIVE

Based on onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous type 2 diabetes mellitus (T2DM), we investigated the Ala45Thr variation in unrelated early-onset and late-onset T2DM with or without diabetic pedigree and unrelated non-diabetic control subjects in Chinese.

METHODS

175 early-onset and 194 late-onset type 2 diabetic patients were further divided into two subgroups according to with or without diabetic pedigree respectively. This NeuroD1-Ala45Thr variation were screened by PCR-direct sequencing in above 369 type 2 diabetic patients and 87 unrelated non-diabetic control subjects. We then compared the distribution of the Ala45Thr variation among the groups, searching for the predictive trends.

RESULTS

Frequencies of the variant (AA + GA genotype) in early-onset T2DM are obviously elevated, especially among diabetic pedigree subjects when compared to non-diabetic controls (p= 0.003) and late-onset T2DM subjects (p = 0.014). However, no significant differences were observed between late-onset T2DM with or without diabetic pedigree and non-diabetic control subjects.

CONCLUSIONS

Our results suggest that 1) the NeuroD1-Ala45Thr variation may itself have an important role in susceptibility to or be in disequilibrium with early-onset T2DM in Chinese; 2) the Ala45Thr may affect the onset pattern of T2DM, i.e., early-onset but not late-onset T2DM in Chinese; and 3) onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous T2DM in Chinese.

Ala45Thr polymorphism of the NEUROD1 gene and diabetes susceptibility: a meta-analysis

A meta-analysis assessed whether the Ala45Thr polymorphism of the neurogenic differentiation 1 (NEUROD1) gene is associated with increased risk of diabetes mellitus type 1 (T1D) or type 2 (T2D). Fourteen case-control studies were analyzed, including genotype data on 3,057 patients with diabetes (T1D n=1,213, T2D n=1,844) and 2,446 controls. Overall and race-specific summary odds ratios (ORs) were obtained with fixed and random effects models. The Thr allele did not significantly increase the overall risk for T1D (OR 1.27 [0.94-1.71], P=0.12) or T2D (OR 1.07 [0.90-1.28], P=0.46). The Thr allele conferred increased susceptibility in subjects of Asian racial descent to T1D (OR 1.88 [1.10-3.21], P=0.020), but not to T2D (OR 1.08 [0.74-1.56], P=0.70). There was no association in subjects of European descent (OR 0.97 [0.76-1.23], P=0.80 for T1D; OR 1.03 [0.88-1.21], P=0.68 for T2D). Larger studies seemed to show more conservative estimates for the association with T1D (P=0.083). The Ala45Thr polymorphism of the NEUROD1 gene has no effect on susceptibility to T2D. It may however be a risk factor for susceptibility to T1D, in particular for subjects of Asian descent, although bias cannot be totally excluded.

NEUROD polymorphism Ala45Thr is associated with Type 1 diabetes mellitus in Czech children

Association of the NEUROD Ala45Thr polymorphism with Type 1 diabetes mellitus (DM) has been found in some but not all populations. We performed a study on the association of two NEUROD exon 2 polymorphisms, the Ala45Thr and the Pro197His, with childhood-onset Type 1 DM in the Czech population. We compared 285 children with Type 1 DM diagnosed under the age of 15 years with 289 non-diabetic control children. The genotypes were determined using novel real-time allele-specific PCR assays in the TaqMan format, and data were analysed using logistic regression. The numbers of subjects with codon 45 genotypes Ala/Ala, Ala/Thr, Thr/Thr were 95, 145, 45 among cases and 117, 130, 42 among controls. Thr45 phenotypic positivity was associated with a significant risk of Type 1 DM (OR=2.01, CI 95% 1.25-3.24) in a multivariate logistic regression model involving also the insulin gene -23HphI genotype and the presence of Type 1 DM-associated HLA-DQB1*0302-DQA1*03 (DQ8) and DQB1*0201-DQA1*05 (DQ2) molecules. No association was observed for the Pro197His mutation which was carried by 5.3% cases and 5.9% controls. Our results confirm that the NEUROD Ala45Thr polymorphism is associated with childhood-onset Type 1 DM.