T594M and G442V polymorphisms of the sodium channel beta subunit and hypertension in a black population

Polymorphisms of the epithelial sodium channel may raise blood pressure by increasing renal sodium reabsorption. This study examines frequency distrib utions and associations with hypertension of the T594M and of the G442V pol ymorphisms of the beta subunit of the epithelial sodium channel in a popula tion-based sample. We studied a stratified random sample of 459 subjects (2 79 women), aged 40-59 years, of black African origin from general practices ' lists within a defined area of South London. All were first generation im migrants. The polymorphic variants were detected using single strand confor mational polymorphism technique (SSCP). The prevalence of hypertension (BP greater than or equal to 160 and/or 95 mm Hg or on drug therapy) was 43%; o f these, 76% were on drug therapy. The main analysis was carried out by thr ee ordered blood pressure categories (I to III) according to increasing blo od pressure and presence or absence of drug therapy. The frequency of the 5 94M variant (heterozygotes and homozygotes) was 4.6%; the frequency of the 442V variant was higher (27.0%). The frequency of the 594M variant increase d with increasing blood pressure category (P = 0.05) and was more common in hypertensives than normotensives. By contrast the frequency of the 442V va riant did not vary across increasing blood pressure categories (P = 0.62). No gender difference was observed. Adjustment for age, sex and body mass in dex did not alter these findings. These results suggest that the 594M varia nt may contribute to high blood pressure in black people of African origin whereas the G442V polymorphism is unlikely to influence blood pressure in t his population.