Endothelial nitric oxide synthase (ecNOS) 4 a/b gene polymorphism and carotid artery intima-media thickness in type-1 diabetic patients

Aim: To study putative associations of the ecNOS 4a/b polymorphism with carotid artery intima-media thickness (IMT) and diabetic complications in young type-1 diabetic patients. Methods: Study participants were 147 type-1 diabetic patients (56 men and 91 women), mean age 30.1 +/- 6.6 years (range 14-44), with a diabetes duration of 13.1 +/- 8.1 years. HbA1c, albuminuria, and lipid status were assessed by standard laboratory techniques, the ecNOS 4a/b genotype was determined by polymerase chain reaction with subsequent polyacrylamide gel electrophoresis. The patients were categorized according to the presence or absence of hypertension, nephropathy and retinopathy. The IMT, which can be used to estimate early stages of arteriosclerosis, was measured by high-resolution ultrasonography. Results: The ecNOS genotypes were distributed as follows: 7.5% a/a, 30.6% a/b, and 61.9% b/b. The IMT values did not differ between the patients with various ecNOS genotypes (a/a: 0.62 +/- 0.13; a/b 0.63 +/- 0.21; b/b: 0.63 +/- 0.13; all: 0.63 +/- 0.15 mm). The prevalence of retinopathy was significantly higher in patients with the b/b genotype (odds ratio: 2.4 vs. a/a+a/b; 95% CI, 1.1-5.3). Conclusions: Our results do not support the hypothesis that the ecNOS 4a/b polymorphism interacts with the development of early carotid arteriosclerosis in young type-1 diabetic patients, but they give grounds to assume that in these patients it could influence the occurence of diabetic retinopathy.