Association analysis between -308G/A and -238G/A TNF-alpha gene promoter polymorphisms and insulin resistance in Mexican women with gestational diabetes mellitus.

BACKGROUND: Gestational diabetes mellitus (GDM) is characterized by insulin resistance. It has been described that tumor necrosis factor α (TNF-α) plays a key role in the pathogenesis of insulin resistance; moreover, increased levels of this proinflammatory cytokine have been reported in women with GDM. Therefore, this study was aimed to assess the presence of associations between the -308G/A and -238G/A polymorphisms and specific haplotypes of the TNF-α gene promoter region and insulin resistance in Mexican women with GDM. METHODS: This study included 51 women with GDM and 44 pregnant women with normal glucose tolerance. Measurements of anthropometric parameters and biochemical estimations were performed. We genotyped the TNF-α -308G/A and -238G/A polymorphisms using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The genotype and allele frequencies of both polymorphisms did not differ significantly between the women with GDM and the controls. However, we found that the frequency of the AG haplotype was significantly increased in the patients with GDM compared with controls (P = 0.019; odds ratio, 4.11; 95% confidence interval, 1.31-12.85). In patients with GDM, we observed that insulin levels and homeostasis model assessment of insulin resistance were significantly higher in women bearing the G/G genotype than in carriers of the G/A and A/A genotypes of the -308G/A polymorphism (P = 0.022 and P = 0.043, respectively). CONCLUSIONS: Our results suggest that the G/G genotype of the TNF-α -308G/A polymorphism increases insulin levels and insulin resistance in women with GDM and that the AG haplotype is a genetic risk factor for GDM in our study population.

Analysis of the association of preeclampsia with polymorphisms of the INS, INSR and IRS1 genes in Mexican women.

BACKGROUND/AIMS: It has been proposed that preeclampsia is a metabolic syndrome of pregnancy. The polymorphisms PstI and MaeIII of INS, NsiI of INSR and Ala513Pro and Gly972Arg of IRS1 have been associated with metabolic syndrome; moreover, the products of these genes are functionally contiguous during insulin signaling. The aim of this study was to assess whether these polymorphisms are associated with preeclampsia. METHODS: 46 normotensive pregnant women and 43 preeclamptic patients were included in the study to develop a clinical, biochemical and genotypic profile of preeclampsia. Clinical evaluation consisted of measurement of blood pressure, height and weight. Peripheral blood samples were collected for determination of fasting glucose and insulin concentrations and for extraction of genomic DNA. Proteinuria was determined. Polymorphisms were detected using PCR-RFLP. RESULTS: The normotensive and preeclampsia groups did not differ significantly in clinical and biochemical traits, except for systolic and diastolic blood pressure (p < 0.0001). Polymorphisms previously associated with metabolic syndrome in Mexican populations were not associated with preeclampsia in Mexican women (p > 0.05). CONCLUSION: The lack of an association between preeclampsia and the polymorphisms studied suggests that other genes whose products do not have direct functional interaction with metabolic syndrome or epigenetic factors may play a role in preeclampsia.