Proteasome subunit alpha type 6 –8C/G gene polymorphism and obesity and insulin resistance in diabetic patients of Dongxiang Nationality

Abstract

Objective To study the association of proteasome subunit alpha type 6 (PSMA6) gene –8C/G polymorphism with obesity and insulin resistance in diabetic patients of Dongxiang Nationality. Methods The genotypes of –8C/G variant in PSMA6 gene were determined by polymerase chain reaction–restriction fragment length polymorphisms assay in 117 patients with type 2 diabetes mellitus and 144 individuals with normal glucose tolerance (NGT) from March 2006 to March 2008. According to body mass index (BMI) or insulin resistance index (HOMA–IR), the patients in the type 2 diabetes mellitus group and NGT group were assigned into the obesity subgroup and normal body weight subgroup or insulin resistance subgroup and non–insulin resistance subgroup, respectively. Meanwhile, the fasting insulin and glucose levels were measured via radioimmunoassay. Results The genotype or allele frequencies of –8C/G variant in PSMA6 gene of type 2 diabetes mellitus group was significantly different from that of the NGT group (χ2=5.805, P=0.016), either between patients with obesity and normal body weight subjects (χ2=11.584, P=0.001), or between patients with insulin resistance and non–insulin resistance subjects (χ2=4.506, P=0.034). Moreover, the frequency of CG+ GG genotype and allele C of insulin resistance subjects was significantly higher than that of the non–insulin resistance subjects in the NGT group(χ2=6.265, P=0.012; χ2=4.572, P=0.033). Conclusion The PSMA6 –8C/G polymorphism is associated with diabetes and insulin resistance and closely related to obesity in people of Dongxiang Nationality. Key words: Diabetes mellitus, non–insulin dependent; Obesity; Insulin; Genes; Proteasome subunit alpha type 6