Evidence for Association of Endothelial Cell Nitric Oxide Synthase Gene Polymorphism with Earlier Progression to End-Stage Renal Disease in a Cohort of Hellens from Greece and Cyprus

Nitric oxide (NO) is thought to be an important factor in the deterioration of renal function. A variable-number tandem 27-bp repeat in intron 4 of the endothelial cell nitric oxide synthase (NOS3) gene has been found to be associated with the plasma levels of NO metabolites. Two alleles are of varied frequencies in different populations (a and b). The shorter allele a has been associated in Japanese populations with the progression of renal disease. Here we investigated this hypothesis by studying the putative role of this polymorphism in a Hellenic population of patients with end-stage renal disease (ESRD). We analyzed the genotypes of 361 ESRD patients and 295 healthy Hellens from Greece and Cyprus. The frequencies of NOS3-4bb, NOS3-4ab, and NOS3-4aa were 0.69, 0.27, and 0.03, respectively, in the control group and 0.71, 0.24, and 0.04 in the group of patients. The data in the two populations were analyzed by the chi-square and Fisher's exact tests. The frequencies of these three genotypes of NOS3-4 polymorphism in the Hellenic population of Greece and Cyprus are similar to those observed in other Caucasian populations. Moreover, our results from three patient groups, autosomal dominant polycystic kidney disease (ADPKD), diabetes mellitus (DM), and non-DM, showed that the frequencies of aa and ab genotypes in the patient populations were not significantly different from those observed in the control group. This work indicates that NOS3-4 polymorphism does not show any association with the development of ESRD in this studied European population. However, examination of the data regarding progression to ESRD within 5 years or after more than 5 years following clinical diagnosis of ADPKD provided evidence of statistical difference (p = 0.048, before Bonferroni correction), with faster progression in the group of ADPKD patients who carried allele a.