Lack of association between endothelial constitutive nitric oxide synthase (ecNOS 4 b/a) gene polymorphism and rheumatic heart disease.

Our aim in this work was to explore any possible association between ecNOS 4 b/a polymorphism and rheumatic heart disease (RHD). In this study, leukocyte DNA was extracted from 139 patients with RHD and 79 healthy control children. After amplification by PCR, the products were separated by electrophoresis in 6% polyacrylamide gel and visualized after ethidium bromide staining with UV light. PCR resulted in a 420-bp fragment (ecNOS4b) when five 27-bp repeats were present in intron 4 of the ecNOS gene, a 393-bp product (ecNOS4a)when only four repeats were present, and 420-bp and 393-bp fragments in heterozygous individuals (ecNOS4b/a). ecNOS4b/a genotyping in the control group gave the following results: b/b genotype (77.2%), b/a genotype(21.5%) and a/a genotype (1.3%). The frequencies in RHD group were as follows: b/b genotype (67.6%), b/a genotype (31.7%), and a/a genotype (0.7%). The b allele/a allele ratio was (88%/12%) in the control group and (83.5%/16.5%) in the RHD group. We found no statistical difference in genotype or allele frequency between these groups. The present study is the first to study the association between ecNOS 4b/a gene polymorphism and RHD, and to find a lack of any association between them. Further investigations of this gene polymorphism alone and in combination with other genes should be encouraged.