Study On The Relationship Between The Endothelial Constitutive Nitric Oxide Synthase (ecNOS ) Gene Polymorphism And The Development Of Diabetic Vascular Complication In Type 2 Diabetic Patients

Object: To exanmine the contribution of the 27-bp repeat polymorphism in intron 4- and the Glu298Asp substitution in extron 7of the endothelial constitutive nitric oxide synthase (ecNOS) gene to the development of diabetic vascular complication,,Methods: (1) Collecting the blod samples according to WHO criteria of type 2 diatetes(2) Extracting and purifying the genomic DNA from the blood samples(3) Using PCR and RFLP assess the ecNOS genotype in 302 unrelated patients with type 2 diatetes and 100 randomly selected healthy control subjectS.(4) Direct sequencing of the representative PCR products with normal and variant patterns,,(5) ANOVA analysis t-test x2test multiple logistic regression analysis were performed by using SPSS 10.0 to analysis the resultResult: (1) Compared with DM1 group Control group, there was significant increase of the genotype frequency for ecNOS 4a/a plus ecNOS 4a/b and significant decrease of the genotype frequency for ecNOS 4b/b in DMEH group (P<0. 05), with DMEH group showing a higher frequency of the 4a allele (P<0.05) .The development of hypertension was positively associated with the presence of the 4a allele of the ecNOS gene (P (0. 05) . The stepwise multiple regression analysis in these type 2 diabetic patients showed that the 27-bp repeat polymorphism in intron4 is the relevant variables for hypertension. The prevalence of theecNOS alleles in each of the groups satisfied the Hardy-Weinberg equilibrium law.(2) There was no differences in genotype in codon 298 of the ecNOS gene and allele frequencies of Glu and Asp between DNS group and DM2 group Control group (P>0. 05) . The number of carriers of the ecNOS 298Asp allele in DN2 group was higher than in DM2 group and Control group, but this difference did not reach the significant level (P>0. 05). Compared with DM2 group P Control group, there was significant increase of the genotype frequency for GG and significant decrease of thegenotype frequency for TT in DN1 group (P (0. 05), with DN1 group showing a higher frequency of the T allele (P<0.05) . The development of diabetic nephropathy was positively associated with the presence of the T allele of the ecNOS gene (P<0.05) . The stepwise multiple regression analysis in these type 2 diabetic patients showed that the Glu298Asp substitution in extron 7 is the relevant variables for hypertension. The prevalence of the ecNOS alleles in each of the groups satisfied the Hardy-Weinberg equilibrium law.(3) There was no differences in the distribution of 27-bp repeat polymorphism in intron 4 and the Glu298Asp polymorphism in extron 7 between patients with diabetic retinopathy and those without diabetic retinopathy , Control group. Similarly, There was no differences in the distribution of 27-bp repeat polymorphism in intron 4 and the Glu298Asp polymorphism in extron 7 between patients with diabetic foot and those without diabetic foot Control group (P>0. 05). Conclusion: (1) The 27-bp repeat polymorphism in intron 4of the ecNOS was significantly associated with hypertension in type 2 diabetic patients.(2) The Glu298Asp substitution in extron 7of the ecNOS was significantly associated with diabetic nephropathy in type 2 diabetic patients. And this gene polymorphism could be an intiating factor for diabetic nephropathy.(3) The 27-bp repeat polymorphism in intron 4 and the Glu298Asp substitution in extron 7of the ecNOS does not contribute to the development of diabetic retinopathy or diabetic foot.