The incidence of NOS3 gene polymorphisms on newborns with large and small birth weight.

The NOS3 gene polymorphisms T-786C, G894T and VNTR 4b/a are associated with a predisposition to the development of Metabolic Syndrome (MetS). The NOS3 gene contributes to a normal pregnancy and fetal development. According to their birthweight, newborns can be classified as: small (SGA), adequate (AGA) or large (LGA) for gestational age. The SGA and LGA present a higher risk of developing disorders related to MetS, both during childhood and adulthood. Therefore, the aim of this work is to relate the incidence of G894T, T-786C and VNTR 4b/a on SGA and LGA newborns and their mothers. 204 blood samples were collected from mothers (102) and the umbilical cords of 102 newborns (SGA = 12; AGA = 47; LGA = 43). The genotyping was performed through PCR-RFLP to evaluate presence of the G894T, T-786C and VNTR 4b/a polymorphisms. A significant difference was found between the groups of newborns in the genotypic frequency of T-786C, but without Hardy-Weinberg equilibrium. The VNTR 4b/a and the G894T polymorphisms showed no significance between the groups. The haplotype analysis showed that the SGA newborns presented the higher frequency of 4aGT (9.8%) and of the 4aTT combination (25.4%), while LGA newborns presented the higher frequency of the 4bTT haplotype (23%). Only the SGA newborns and their mothers presented the 4aTC haplotype. In conclusion, the NOS3 polymorphisms do not appear to be a factor to inadequate birth weight. However, the G894T and VNTR 4b/a polymorphisms, and the haplotype 4aTC, seem to influence the occurrence of SGA.