Study On The Relations Between The Protein Tyrosine Phosphastase-1B Gene Polymorphism And Type 2 Diabetes

Objective: Insulin signal to be restrained is an important factor in insulin resistance in type 2 diabetes mellitus. The increaser expression of PTP-1B can restrain the insulin signal conduction, which will result in insulin resistance and type 2 diabetes mellitus. At the present, the mutant genes are considered the major influences on the expression of PTP-1B. There were some mutation sites of PTP-1B gene. But the significance of mutation differs according to different patients and different sites. Our study is to investigate the 981 polymorphism of protein tyrosine phosphastase-1B (PTP-1B) in type 2 diabetes mellitus in Dalian residents by group study and family line study.Methods: The research objects came from Dalian. The patients with T2DM in group study were composed of 80 patients with T2DM in ancestry selected from Jan 2005 to Feb 2006 and 21 patients with T2DM scattered. There were 101 patients (49 men and 52 women) with an average age of 55±13.4 years。The 309 non-diabetic objects with fasting glucose less than 5.6 mmol/L or OGTT glucose less than 7.8 mmol/L ( 152 men and 157 women, with an average age of 51±14.8 years) were selected. The objects in family line study were the same as T2DM ancestries. A patient with T2DM, a first grade blood relative without DM and a spouse of the patient with T2DM were selected. Genomic DNA was isolated from peripheral blood cell according to standard procedures. All objects were genotyped using PCR amplification of exon 10, followed by digestion with the restriction enzyme AvaI. The genetypes were read after separation of the digested products with 8% SDS-PAGE. There are three fragments (242bp, 73bp, 315bp) of polymerase chain reaction. Different distribution in genotypes between T2DM and non-diabetic objects was analyzed. We analyzed the haplotypes that the three gengtypes were composed.Results: 1.The genetypes of PTP-1B gene 981 site are homozygote CC and TT, heterozygotes CT. In group study , the frequencies of CC gene of T2DM patients in group study are 68%, CT 28%,TT 7%, the frequencies of the C allele and the T allele were 79.2% and 20.8%. The frequencies of CC gene of non-diabetes are 68%, 28% and 3%, the frequencies of the C allele and the T allele were 79.2% and 20.8%. The frequencies of genetypes and the frequencies of the alleles in T2DM patients are similar to those in non-diabetes controls in group study.2.The frequencies of CC gene of T2DM patients in group study are 65%, CT 30%,TT 5%, the frequencies of the C allele and the T allele were 80% and 20%; The frequencies of CC gene of the first grade blood relative without DM are 62.5%,28.8% and 7%, the frequencies of the C and T allele were 76.9% and 23.1%; The frequencies of CC gene of normal controls are 75%,20%,5%, the frequencies of the C and T allele were 85% and 15%. The frequencies of genetypes and the frequencies of the alleles in T2DM patients are similar to those in non-diabetes controls in ancestry study.Conclusion: We found no association between the 981 polymorphism of protein tyrosine phosphastase-1B (PTP-1B) and the risk of type 2 diabetes in the study conducted in DaLian.