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The association between melatonin receptor 1B gene polymorphisms and type 2 diabetes mellitus (T2DM) in Chinese populations: a meta-analysis.

BACKGROUND
Type 2 diabetes mellitus (T2DM) is associated with a large number of genetic variants of melatonin receptor 1B (MTNR1B), but the results of studies involving different racial groups have been inconsistent. Thus, we carried out a meta-analysis to evaluate the correlation between the MTNR1B variants and T2DM in the Chinese population.


METHODS
A systematic search was conducted of English-language databases including PubMed, Embase, and Medline, and Chinese-language databases including China National Knowledge Infrastructure (CNKI), Wanfang Database, and CQVIP to collect relevant articles published up to January 31, 2020. Count data were pooled using odds ratio (OR) and 95% confidence interval (CI), and the analysis was performed using the "meta" package of the R3.5.1 software.


RESULTS
Nine articles involving 10,127 subjects in the T2DM group and 10,885 subjects in the healthy control group were entered into the final analysis. Four articles reported the rs1387153 variant of the MTNR1B gene in Chinese populations. Meta-analysis showed there to be no correlation between the C-allele and TT genotype and the occurrence of T2DM. However, a subgroup analysis based on the HardyWeinberg equilibrium (HWE) revealed that the frequency of the CC genotype was significantly lower in the T2DM group than in the control group (OR: 0.88; 95% CI: 0.78, 1.00; P=0.049). Seven articles reported the rs10830963 variant of the MTNR1B gene among Chinese populations. Meta-analysis discovered that the G-allele was correlated with the T2DM occurrence. The frequency of the G-allele in the T2DM group was 1.07 times that in the control group (95% CI: 1.02, 1.12). The GG genotype was associated with the occurrence of T2DM, with its frequency in the T2DM group 1.15 times that in the control group (95% CI: 1.05, 1.25) (P<0.05); however, there was no correlation between the CC genotype and T2DM.


CONCLUSIONS
There is a correlation between the CC genotype of the rs1387153 variant in the MTNR1B gene and T2DM in the Chinese population, although this finding needs to be verified in studies with large sample sizes. The G-allele and GG genotype of the rs10830963 variant in the MTNR1B gene are associated with the occurrence of T2DM.