Obesity Has an Interactive Effect with Genetic Variation in the Activating Transcription Factor 6 Gene on the Risk of Pre-Diabetes in Individuals of Chinese Han Descent

Endoplasmic reticulum (ER) stress is one of the contributing factors to the development of b-cell failure in type 2 diabetes. ER stress response through ATF6 has been shown to play an important role in insulin resistance and pancreatic beta-cell function. We investigated whether genetic polymorphisms in ATF6 were associated with the risk of pre-diabetes in a Chinese Han population, and whether they had a synergistic effect with obesity. Our samples included 828 individuals who were diagnosed as pre-diabetic, and 620 controls. The minor allele A at rs2340721 was associated with increased risk for pre-diabetes(p = 0.013), and this association was still significant after adjusting for gender, age, body mass index (BMI), and waist-hip ratio (p' = 0.011). BMI, treated as a continuous variable, and rs2340721 had an interactive effect on pre-diabetic risk(p for interaction = 0.003, beta = 0.106). Carriers of GG at rs7522210 were also at a higher risk compared to non-carriers (OR = 1.390, 95%CI:1.2061.818, p = 0.013, adjusted OR' = 1.516, 95%CI:1.1012.006, p' = 0.006). GG homozygotes had increased fasting blood glucose (FBG) levels(GG vs CX: 5.6 +/- 0.52 vs 5.5 +/- 0.57 mmol/L, p = 0.016), lower insulin levels (0,30,120 minutes after glucose load) (p<0.05), and reduced areas under the insulin curve than non-carriers(GG vs CX:67.3(44.2102.3) vs 73.1(49.4111.4), p = 0.014). rs10918270 was associated with FBG, and rs4657103 with 2 hour glucose levels after a 75 g glucose load. We also identified a haplotype of TTAG composed of rs4657103, rs2134697, rs2340721, and rs12079579, which was associated with pre-diabetes. The genetic variation in ATF6 is associated with pre-diabetes and has interactive effects with BMI on pre-diabetes in the Chinese Han population.