Inducible nitric oxide synthase (iNOS) gene polymorphism in pre-eclampsia: A pilot study in North India

Pre-eclampsia is one of the most frequent complications of pregnancy, however, little is known about its aetiology. The objective of this study was to investigate the association between inducible nitric oxide synthase (iNOS) genotypes and pre-eclampsia. We also measured the concentrations of tumour necrosis factor-alpha (TNF-alpha), nitric oxide (NO) and superoxide dismutase (SOD) in patients with pre-eclampsia to evaluate their relations to the single nucleotide polymorphisms (SNPs) observed. This cross-sectional study included 30 pregnant women with pre-eclampsia and 30 healthy pregnant women. They were screened at 28th, 36th weeks of gestation and just after delivery (within 48 h), and their blood samples were analysed for NO, SOD, TNF-alpha and iNOS gene polymorphism. Patients with pre-eclampsia at 36 weeks gestation showed significantly increased serum NO levels (P = 0.007), whereas SOD activity was decreased significantly (P = 0.004). A doublefold increase was observed in TNF-alpha levels at 36 weeks in patients with pre-eclampsia (P = 0.003) which decreased significantly (P = 0.001) after delivery. A total of four SNPs were observed, of which two (G300A exon 8 and G274T exon 16) showed statistically significant association with pre-eclampsia. When compared, G274T exon 16 SNP also showed association with TNF-alpha levels and SOD activity in pre-eclamptic patients. As pre-eclampsia is a disease of multifactorial aetiopathology, NO, TNF-alpha, SOD activity and NOS2A polymorphism might play an intermingled role in its development.