GENETIC POLYMORPHISMS IN THE ENDOTHELIAL NITRIC OXIDE SYNTHASE GENE IN ELITE ENDURANCE ATHLETES AND CONTROLS

695 In the GENATHLETE case control study, we examined the contribution of two polymorphisms in the gene encoding for the endothelial nitric oxide synthase (NOS3). The hypothesis was that this particular gene, as a result of its key role in the synthesis of NO and its potential influence on endothelial function, may play a role in discriminating elite endurance athletes (EEA) from sedentary controls (SC). The EEA group included 213 Caucasian males recruited on the basis that they had a VO2max > 75ml/kg/min. The SC group comprised 197 unrelated sedentary males who had VO2max values below 50ml/kg/min. PCR technique was used to amplify a microsatellite (CA repeat) containing region in intron 13 and a second fragment in intron 4 including a 27bp repeat in the NOS3 gene, located on chromosome 7q36. No difference between EEA and SC was found in genotype distributions or allelic frequencies for the 27bp repeat. The numbers and p-values from chi-square tests for carrier status of the 162bp and 170bp allele of the CA repeat in intron 13 for EEA and SC are presented in table 1.Table 1: Allele distributions and results from chi-square analysis for the 162bp and the 170bp allele of the CA repeat in the NOS3 gene. Chi-square analysis for the allelic distribution of the CA repeat revealed a significant difference between the two groups (p=0,018).Comparing carriers and non-carriers for the various CA repeat alleles, we found significant differences between SC and EEA, with more SC subjects carrying the 170bp allele and more EEA subjects with the 162bp allele (Table 1). In summary, we found suggestive evidence that the two fragments are associated with EEA and SC status, respectively, and may account for some differences between EEA and SC.