Contribution of the Akt2 gene to type 2 diabetes in the Chinese Han population.

Background: The Akt2 protein kinase is thought to be a key mediator of the insulin signal transduction process. Akt2 is suggested to play a role in glucose metabolism and the development or maintenance of proper adipose tissue and islet mass. In order to determine whether the Akt2 gene plays a role in the pathogenesis of type 2 diabetes characterized by insulin resistance, and to further identify if variations in this gene have a relationship with type 2 diabetes, we sequenced the entire coding region and splice junctions of Akt2 and made a further case-control study to explore the association between single-nucleotide polymorphisms (SNPs) in this gene and type 2 diabetes in the Chinese Han population.

Methods: We selected 23 probands with a type 2 diabetic pedigree whose family members' average onset age was within 25 to 45 years old. The body mass index of all the participants was lower than 28 kg/m(2) and all of them were insulin-resistant (the fasting insulin level > 100 pmol/L or 16 µIU/ml). The entire coding region and splice junctions of Akt2 were directly sequenced in these 23 probands. SNPs with a frequency of minor allele over 20 percent were selected to be further studied in a case-control study. We chose 743 non-diabetic subjects as the control group and 742 type 2 diabetic patients as the case group. All these subjects were genotyped. A Snapshot Technology Platform (Applied Biosystems) was used for genotyping.

Results: The Akt2 genes from all 23 subjects were successfully sequenced. We did not identify any mutation in the type 2 diabetic pedigree. Two SNPs were identified, 13010323T > C and 13007939G > T. 13010323T > C was in intron 9, which was the location of rs2304188 reported in Genbank. Its minor allele frequency was 13.04%. 13007939G > T was in the 3'-untranslated region (UTR) of exon 14, which was the location of rs2304186 reported in Genbank. Its minor allele frequency was 34.78%. The allele frequency of rs2304188 and rs2304186 were consistent with the frequency reported in Genbank. In the case-control study with 742 patients and 743 controls, there was no significant difference between the two groups for the allele frequency of rs2304186 (odd ratio: 0.96, 95% confidence interval: 0.82 - 1.12, P = 0.597).

Conclusions: The Akt2 gene is not a major cause of diabetes in a non-obese Chinese Han population characterized by insulin resistance. There is no significant relationship between rs2304186 and type 2 diabetes in the Chinese Han population.