Relationship between Calpain-10 Gene Polymorphism and Insulin Resistance Phenotypes in Chinese

In order to determine whether the variations in the calpain-10 gene constitutes risk of type 2 diabetes (T2DM) in Chinese, the frequency of UCSNP-43, 44 in 268 adults newly diagnosed with T2DM (according to the 1999 ADA criteria) and 153 non-diabetic control subjects was investigated. For all subjects, the height, weight, waist-to-hip ratio (W/H) and blood pressure, as well as following parameters were measured: (1) 75-g oral glucose tolerance test with insulin, C-peptide, HbA1c and blood lipid profiles; (2) Genomic DNA extracted from peripheral blood lymphocytes was genotyped for UCSNP-43 (calpain-10-g.4852 G/A) and UCSNP-44 (calpain-10-g.4841 T/C) by sequencing a polymerase chain reaction (PCR)-amplified fragment. PCR product was selected by single strand conformation polymorphism (SSCP) and then sequenced. The results showed that there was significant difference between T2DM group and normal control group in allele frequencies, haplotype frequencies, or haplotype combinations of UCSNP-43 and -44 either. But in newly diagnosed T2DM group, it was found that the individuals with the genotype UCSNP-44 T/C+C/C had significantly increased fasting and post-challenge insulin levels (FIns and P2hIns), consistent with reduced insulin sensitivity. In the BMI>25 subgroup, the differences were even more significant. It was demonstrated that the Calpain-10 gene polymorphism UCSNP-44 was associated with insulin sensitivity and FIns and P2hIns in newly diagnosed T2DM, although Calpain-10 doesn’t appear as a major diabetes susceptible gene in this population.