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GERA 1: Genetic Epidemiology of Responses to Antihypertensives 1

GERA1 was a prospective interventional trial of hydrochlorothiazide in 600 participants to find predictors of BP response and estimate how much inter-individual variation could be explained by the predictors in a biracial (African American & Caucasian) sample aged 18-60 with essential hypertension. Participants withdrew from antihypertensive medications for at least four weeks, were stabilized on a standardized sodium diet and then were treated with HCTZ 25 mg for four weeks. RAAS activity, glucose, total cholesterol, HDL, triglyceride, uric acid, potassium, sodium, and creatinine were measured at enrollment, baseline, and end of treatment. Black race and female gender were associated with greater BP reduction, and combining the effects of all identified predictors accounted for 38% of inter-individual variation in SBP and 20% of DBP response. The systematic search revealed numerous predictors of BP response to the standard dose of HCTZ but the majority of variation remained unexplained.