T594M variant of the epithelial sodium channel β-subunit gene and hypertension in individuals of African ancestry in South Africa

The T594M variant of the β-subunit of the sodium epithelial channel (ENaC) gene may contribute to hypertension in individuals of African origin. A case-control study was performed to assess the role of the ENaC gene variant as an independent risk factor for hypertension in subjects of African ancestry. The effects of the ENaC gene variant on ambulatory blood pressure (BP) in hypertensive individuals and on office BP in hypertensive individuals and control subjects were also assessed. A total of 519 hypertensive patients with 24-h ambulatory BP (ABP) values determined while off medication, and 514 normotensive South African individuals of African ancestry were genotyped for the T594M polymorphism of the ENaC gene. A total of 22 (4.2%) hypertensive participants compared with 23 (4.5%) normotensive participants possessed the T594M variant (odds ratio = 1.06, confidence interval = 0.58 to 1.92, not significant). A similar genotype frequency distribution was noted in subjects representing the two predominant chiefdoms (Nguni and Sotho) in both case and control groups. No differences in frequency distribution of the T594M variant were noted with respect to either body mass index or gender. There were no differences in clinic or ambulatory mean, day, or night BP between hypertensive patients with or without the variant. Similarly, no differences were noted in clinic BP between control subjects with or without the variant. Other phenotypic parameters (including age and hypertension duration and severity) were also similar among hypertensive patients with or without the variant. These results do not support an important role for the T594M variant of the ENaC gene contributing to either the development or severity of hypertension in subjects of African ancestry.