Genetic variation of the gamma subunit of the epithelial Na+ channel and essential hypertension. Relationship with salt sensitivity

We evaluated the association of a common polymorphism in gamma ENaC, consis ting in a C to G transversion in codon 649, with essential hypertension and to the presser response to salt in whites. Two hundred fifteen essential h ypertensive patients, and 137 normotensive controls were genotyped for the gamma 649 ENaC polymorphism by polymerase chain reaction method and diagnos tic restriction enzyme digestion. The genotype distribution of the gamma 64 9 ENaC polymorphism in the hypertensives, 129 CC (60%) and 86 CG/GG (40%) w as not significantly different from that of the control group, 84 CC (61%) and 53 CG/GG (39%) (P = .81). Salt sensitivity was assessed in a group of 4 8 patients by 24-h mean blood pressure response to changes in salt intake. Nineteen patients were diagnosed as salt sensitive, whereas 29 had salt-res istant hypertension. The gamma 649 ENaC genotype distribution in salt-sensi tive patients was 12 CC (63%) and 7 CG/GG (37%), not significantly differen t from the distribution in the salt-resistant group, 19 CC (65%) and 10 CG/ GG (35%), P = .87. The changes in systolic, diastolic, and mean blood press ure as measured by ambulatory blood pressure monitoring, and in plasma reni n activity and plasma aldosterone induced by high salt diet were not differ ent among the gamma 649 ENaC genotypes. In the present study we found no as sociation between the gamma 649 ENaC polymorphism and essential hypertensio n or salt sensitivity. Although these data do not support a major causative role for this polymorphism, we cannot exclude that a functional mutation e lsewhere in ENaC might be associated with essential hypertension. Am J Hype rtens 2000;13:648-653 (C) 2000 American Journal of Hypertension, Ltd.