The aim of the study. Retinopathy of prematurity (ROP) which is associated with abnormal retinal vessel development is the leading cause of visual loss affecting preterm infants. Endothelial nitric oxide synthase (eNOS) has been implicated to play a central role both in retinal angiogenesis and vasculogenesis. We investigated therefore functional genetic polymorphisms of eNOS in the pathogenesis of ROP.

Methods. eNOS T-786C and 27-bp repeat (eNOS b/a) genotypes were determined using allele-specific polymerase chain reaction in 105 low birth weight (LBW) preterm infants treated for ROP (treated group). 127 LBW infants not requiring treatment for the risk of proliferating ROP (untreated group) served as controls.

Results. The genotype distribution of eNOS 27-bp repeat polymorphism was significantly different (p=0.015), whereas the genotype distribution of eNOS T-786C was not different (p=0.984) between the two groups. There was no difference in the distribution of either the ”a” allele (p=0.153) nor of the C allele (p=0.867) comparing the two groups. Multiple logistic regression analysis revealed that male gender (p=0.046) and eNOS aa genotype (p=0.047 vs. ab genotype and p=0.022 vs. bb genotype) were significantly associated with ROP requiring treatment. The haplotype estimations based on the detected genotype distributions showed that the prevalence of aT and bT haplotypes was significantly increased in the group treated for ROP.

Conclusions. The present study suggests that functional eNOS 27-bp repeat polymorphism might be associated with the risk of severe ROP.