Interaction according to urinary sodium excretion level on the association between ATP2B1 rs17249754 and incident hypertension: the Korean genome epidemiology study

OBJECTIVE: We examined an interaction according to the estimated 24-h urinary sodium excretion on the association between ATP2B1 rs17249754 and incident hypertension. METHODS: We assessed the incidence of hypertension in 1780 participants aged 45 to 75 years without cardiovascular diseases. DNA genotyping was performed using the Affymetrix Single Nucleotide Polymorphism (SNP) array 5.0. Because of previously reported associations with hypertension in various populations including Koreans, ATP2B1 rs17249754 was determined. Sodium intake was assessed by estimating the 24-h urinary sodium excretion with a Kawasaki formula from a spot urine sample. We utilized Cox proportional hazard models to test an interaction according to urinary sodium excretion on the association between ATP2B1 rs17249754 and incident hypertension. RESULTS: The incident hypertension was increased as sodium excretion level was increased. We confirmed that the ATP2B1 rs17249754 polymorphism had significant association with hypertension. We found that the association was modified by urinary sodium excretion level (p-value = 0.006); the mutant type (AA allele, previously recognized as a protective allele) with <4 g/day urinary sodium excretion had an inverse association on hypertension compared with the wild types (GG+GA) (HR = 0.39, 95% confidence interval (CI) 0.17-0.90), whereas the mutant type with ≥6 g/day urinary sodium demonstrated a significantly increased risk of hypertension (HR = 1.89, 95% CI 1.05-3.43). CONCLUSIONS: In this 6-year longitudinal study, our findings suggest that excessive sodium intake estimated from urinary sodium excretion significantly modified the risk of developing hypertension associated with ATP2B1 rs17249754 genetic trait. That is, carriers with ATP2B1 rs17249754 homozygote mutant allele may be at higher risk of hypertension, when they consume excessive sodium intake.