NEW YORK (Reuters Health) – In older hypertensive patients, the "deletion" polymorphism of the angiotensin converting enzyme (ACE) gene is associated with an increased sodium sensitivity, researchers report.
Dr. Donald R. Dengel, from the University of Minnesota, Minneapolis, and colleagues studied 35 hypertensive patients, mean 62.9 years of age. Patients were placed on a high sodium diet (200 mmol/day) for 8 days and then a low sodium diet (20 mmol/day) for 8 days after a 1-week washout period.
Twenty-four of the patients were sodium-sensitive, showing a 5 mm Hg or greater increase in mean arterial blood pressure in response to the high sodium diet.
While on the high sodium diet, patients who were homozygous for the insertion allele (II) of the ACE gene had a lower mean arterial blood pressure response (p = 0.04) compared with those with the insertion/deletion (ID) genotype (p = 0.0001) and with those homozygous for the deletion allele (DD) (p = 0.05), Dr. Dengel's team notes.
Among patients with the DD and ID alleles, the prevalence of sodium sensitivity was higher (71% and 83% respectively, p = 0.0083) than in patients with the II allele (25%), according to the report in the December 2001 issue of the American Journal of Hypertension.
Dr. Dengel and colleagues note that "this finding supports the hypothesis that sodium sensitivity is, in part, genetically determined."
But they suggest that "it is possible that age and the ACE gene interact to cause the increase in the prevalence of sodium sensitivity with aging. Sodium sensitivity in younger individuals may not demonstrate the same association with the ID and DD polymorphism of the ACE gene."