Objective: To study allelic frequency of tumor necrosis factor-alpha (TNF-alpha) in gestational diabetes mellitus (GDM) of Han ethnicity in north China and to determine whether there is a specific allele of TNF-alpha associated with GDM susceptibility.
Methods: By using PCR-RFLP, we detected the distribution of TNF-alpha promoter alleles frequency in GDM women and control normal pregnant women. Plasma TNF-alpha levels and insulin levels were measured by radioimmunoassay.
Results: (1) There was a significant increase of A alleles frequency of TNF-alpha promoter -308 gene in GDM women compared with control group (61.4% vs 30.0%, P < 0.05) and an increase of the AA + GA genotype was observed in GDM group (71.4% vs 37.1%, P < 0.05). (2) In GDM group, the patients carrying the AA + GA genotype had higher plasma TNF-alpha levels (52 +/- 13 vs 14 +/- 4, P < 0.05) and a lower insulin sensitivity (13.6 +/- 6.5 vs 1.9 +/- 0.2, P < 0.05) compared with those carrying the other genotype (GG).
Conclusions: The 308 G-->A polymorphism of TNF-alpha promoter gene is involved in the pathophysiology of insulin resistance and gestational diabetes mellitus.