ABSTRACT
INTRODUCTION: Studies have been conducted to investigate the association between rs10830963 of MTNR1B and the risk of gestational diabetes mellitus (GDM), but with inconclusive results. We aimed to clarify these controversies, especially with regard to the association in the Chinese population. MATERIAL AND METHODS: A systemic literature reference search inclusive to August 12, 2016 yielded 35 articles, from which 11 studies met the inclusion criteria for the final meta-analysis, including 3889 patients with GDM and 6708 controls. RESULTS: We found statistically significant associations between rs10830963 and GDM using odds ratios (ORs) and 95% confidence intervals (CIs) [GG genotype vs. CC genotype: OR = 1.70, 95% CI: 1.38-2.10; G allele vs C allele: OR = 1.27, 95% CI: 1.20-1.36; GG+CG vs. CC (dominant model): OR = 1.31, 95% CI: 1.20-1.44; GG vs CG+CC (recessive model): OR = 1.41, 95% CI: 1.26-1.58]. In subgroup analyses stratified by ethnicity, we also observed rs10830963 to be associated with significantly increased risk of GDM in all genetic models in the Chinese population. CONCLUSIONS: Our meta-analysis indicated that the rs10830963 polymorphism might serve as a risk factor of GDM in the Chinese population.
ABSTRACT
GLI2 is a key mediator of the sonic hedgehog (Shh) signaling pathway and plays an important role in neural tube development during vertebrate embryogenesis; however, the role of gli2 in human folate-related neural tube defects remains unclear. In this study, we compared methylation status and polymorphisms of gli2 between spina bifida patients and a control group to explore the underlying mechanisms related to folate deficiency in spina bifida. No single nucleotide polymorphism was found to be significantly different between the two groups, although gli2 methylation levels were significantly increased in spina bifida samples, accompanied by aberrant GLI2 expression. Moreover, a prominent negative correlation was found between the folate level in brain tissue and the gli2 methylation status (r = -0.41, P = 0.014), and gli2 hypermethylation increased the risk of spina bifida with an odds ratio of 12.45 (95 % confidence interval: 2.71-57.22, P = 0.001). In addition, we established a cell model to illustrate the effect of gli2 expression and the accessibility of chromatin affected by methylation. High gli2 and gli1 mRNA expression was detected in 5-Aza-treated cells, while gli2 hypermethylation resulted in chromatin inaccessibility and a reduced association with nuclear proteins containing transcriptional factors. More meaningful to the pathway, the effect gene of the Shh pathway, gli1, was found to have a reduced level of expression along with a decreased expression of gli2 in our cell model. Aberrant high methylation resulted in the low expression of gli2 in spina bifida, which was affected by the change in chromatin status and the capacity of transcription factor binding.
