Abstract P234: Genetic Variants of the Kallikrein-kinin System Associated with the Salt Sensitivity of Blood Pressure: The GenSalt Study

Abstract

The kallikrein-kinin system (KKS) has been implicated in the pathogenesis of salt-sensitive hypertension in animal models. We comprehensively examined the association between genetic variants of the KKS and blood pressure (BP) response to dietary sodium intervention among participants of the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study. A 7-day low-sodium dietary intervention followed by a 7-day high-sodium dietary intervention was carried out among 1,906 GenSalt participants from rural areas of north China. Nine BP measurements were obtained at baseline and on the last three days of each intervention period using a random-zero sphygmomanometer. The percentage changes in mean BP from baseline to low-sodium intervention and from low-sodium to high-sodium intervention were used to assess individual salt-sensitivity. A total of 205 tagSNPs and functional SNPs of eleven genes of the KKS ( BDKRB1 , BDKRB2 , CPN1 , CPN2 , CPM , ECE1 , KLK1 , KLKB1 , KNG1 , MME , SERPINA4 ) were selected and genotyped in this study. Single marker analyses were conducted using the Family Based Association Test program. Genetic variants in the bradykinin receptor B2 ( BDKRB2 ) and endothelin converting enzyme 1 ( ECE1 ) genes showed significant associations with salt sensitivity even after adjusting for multiple testing using the false discovery rate method. SNP rs11847625 of BDKRB2 was significantly associated with systolic BP (SBP) response to low-sodium intervention ( P = 0.0001). Compared to its major allele G, carriers of the minor allele C had greater SBP decrease during low-sodium intervention. Furthermore, a haplotype containing allele C was associated with greater SBP increase to high-sodium intervention ( P = 0.0009). Seven SNPs of ECE1 , one of the degrading enzymes of kinins, were significantly associated with diastolic BP (DBP) response to low-sodium intervention ( P values ranged from 0.0003 to 0.002). Two haplotypes in the linkage disequilibrium block including these seven SNPs were significantly associated with DBP response to low-sodium intervention (P=0.0004 and 0.003, respectively). Our study found that the genetic variants of the KKS were associated with salt sensitivity of BP. Replication and functional studies of the identified variants are warranted in the future.