Polymorphism in exon 6 of the human NT5E gene is associated with aortic valve calcification

NT5E encodes ecto-5'-nucleotidase (e5NT, CD73) which hydrolyses extracellular AMP to adenosine. Adenosine has been shown to play a protective role against aortic valve calcification (AVC). We identified two nonsynonymous missense single nucleotide polymorphisms (c.1126A > G, p.T376A and c.1136T > C, p.M379T) in exon 6 of the human NT5E gene. Since both substitutions might affect e5NT activity and consequently alter extracellular adenosine levels, we evaluated the association between NT5E alleles and calcific aortic valve disease in 119 patients (95 patients with AVC and 24 controls). In AVC patients, the frequency of the G allele at c.1126 and the frequency of the GG genotype as well as the frequency of the C allele at c.1136, and the frequencies of CC and TC genotypes tended to be higher as compared to controls. The allele and genotype frequencies in AVC patients and controls were also compared to those calculated from the 1000 Genomes Project data for control individuals of European ancestry (n = 503). We found that the frequency of the C allele at c.1136 is significantly higher in patients with AVC than in the European controls (0.111 vs. 0.054, P = 0.0052). Moreover, e5NT activity in aortic valves showed a trend toward lower levels in AVC patients with CC and TC genotypes than in those with the TT genotype. Our findings indicate that the genetic polymorphism of NT5E may contribute to the pathogenesis of calcific aortic valve disease and that the C allele of SNP c.1136 is associated with an increased risk of AVC.