Genetic Polymorphism of Endothelial Nitric Oxide Synthase in Sickle Cell Disease Patients in South-Eastern Nigeria

Background: Sickle cell disease (SCD) is an inherited blood disorder resulting from a point mutation of thymine (T) for adenine (A) at codon 6 of the gene for beta-globin chain of haemoglobin, leading to substitution of Valine for Glutamate at position 6 of the amino acid sequence, thereby shifting the isoelectric point of the protein. The single nucleotide polymorphism (SNP) (T-786C) in the 5' promoter region which affects the expression of endothelial nitric oxide synthase (ENOS) gene is critical in determining the predisposition of humans to diseases including SCD. This work was therefore aimed at investigating the presence of SNP (T-786C) in the 5' promoter region of ENOS gene in patients with SCD with respect to controls, visiting the University of Nigeria Teaching Hospital (UNTH) Ituku-Ozalla, Enugu State, south-Eastern Nigeria. Materials and Methods: The study recruited a total of 50 subjects including 20 SCD patients (SS), 15 sickle cell carriers (AS) and 15 healthy non-carriers (AA). DNA was extracted from venous blood samples; PCR amplification was done using specified primers to the region of polymorphism, and finally followed by HpaII restriction enzyme digestion. Results: The results obtained showed only TT genotype across all samples, and so could not establish any relationship between the SNP T-786C ENOS gene region and SCD. There was presence of the same genotype in both test and control groups. Conclusion: This research findings therefore suggest that T-786C ENOS gene polymorphism is not associated with SCD in south-Eastern Nigeria and thus cannot genetically influence the phenotypic outcome of the disease in the clime.