ADRB1 and heart failure: Although a number of studies have indicated that the β1-AR gene variant at position 389 either alone or in synergy with the α2C-AR Del322-325 variant modifies the response to β-AR-blocker therapy in heart failure,13-15 whether this change is in part attributed to an impact of these gene variants on the risk for the clinical expression of the phenotype for heart failure, the severity of heart failure, or the progression of heart failure independent of β-AR-blocker therapy is uncertain.