Endothelial nitric oxide synthase gene polymorphism and elite endurance athlete status: the Genathlete study.

In the Genathlete study, we examined the contribution of three polymorphisms in the endothelial nitric oxide synthase (NOS3) gene to discriminate elite endurance athletes (EEA) from sedentary controls (SC). The EEA group included a total of 316 Caucasian males with a VO2max >75 mL/kg. The SC group comprised 299 unrelated sedentary Caucasian males who had VO2max values below 50 mL/kg. The polymerase chain reaction technique was used to amplify a microsatellite (CA)(n) repeat in intron 13, a 27 bp repeat in intron 4 and a third fragment in exon 7 containing the Glu298Asp SNP. No difference was found between the EEA and SC groups for the 27 bp repeat and the Glu298Asp polymorphism. Chi-square analysis of the overall allelic distribution of the (CA)(n) repeat revealed no significant difference between the two groups (P=0.135). However, comparing carriers and non-carriers for the most common (CA)(n) repeat alleles, we found significant differences between SC and EEA, with more EEA subjects carrying the 164 bp allele (P=0.007). In summary, we found suggestive evidence that the 164 bp allele of the (CA)(n) repeat in intron 13 is associated with EEA status and may account for some of the differences between EEA and SC.