The present population-based, case-control study also showed significant gender-specific (male only) differences in genetic markers between essential hypertension patients and control individuals. Moreover, we noted a significant gene-by-gender interaction with BP traits in this study. Several studies have reported gender-specific effects of gene variants and gene-by-gender interactions in human hypertension [19–22]. These data support our findings. One potential mechanism by which two common SNPs (C602A and T1559C) might contribute to essential hypertension in males is that these two variants increase susceptibility to endothelial dysfunction, inflammation and atherosclerosis. Although this is consistent with the fact that males have higher incidences of essential hypertension than females [23], more studies were needed. As for SNP T1880C, both genotypes and alleles exhibited similar frequencies in hypertensive patients and healthy normotensive subjects, even after adjusting for age and sex.