Possible interactions of the endothelial constitutive nitric oxide synthase genotype with alcohol drinking and walking time for high serum uric acid levels among Japanese

A variable number of tandem repeat polymorphism located in intron 4 of the gene for endothelial constitutive nitric oxide synthase (ecNOS) is reported to be significantly associated with the nitric oxide level, which influences serum uric acid (SUA). To cast light on any association between the polymorphism and hyperuricemia, as well as gene-environment interactions, a cross-sectional study was conducted for 703 health checkup examinees (213 men and 490 women). The age-adjusted odds ratio (aOR) of hyperuricemia (≥7 mg/dL) for ecNOS 4/4, 4/5, or 5/6 genotypes (non-5/5 group) as compared with the 5/5 genotype was 2.41 (95% confidence interval [CI], 1.09-5.30) in men. The aORs for drinking alcohol relative to never drinking were found to be 8.93 (95% CI, 1.02-78.16) among men with non-5/5 genotypes and 1.76 (95% CI, 0.59-5.26) for their 5/5 counterparts. Moreover, the aORs for heavy drinking (≥50 mL/d) were 23.16 (95% CI, 2.14-250.35) and 2.48 (95% CI, 0.75-8.15), respectively. The interaction between the genotype and current drinking was 3.10 (95% CI, 0.45-21.41). The aORs for more than 30 minutes of daily walking relative to 30 minutes or less of daily walking were found to be 1.54 (95% CI, 0.40-5.95) among men with non-5/5 genotypes and 0.31 (95% CI, 0.12-0.81) for their 5/5 counterparts. The interaction between the genotype and more than 30 minutes of daily walking was 4.92 (95% CI, 0.95-25.64). This study indicated that the ecNOS variable number of tandem repeat polymorphism influences the SUA level in men. Although the interactions were not significant, alcohol intake may be more influential among men with non-5/5 genotypes and walking may be more effective among men with the 5/5 genotype. These findings would be informative for men with high SUA levels.