Despite the belief that treatment with an aldosterone receptor blocker in conjunction with an ACE inhibitor is relatively contra-indicated because of the potential for serious hyperkalaemia, 17 the addition of an aldosterone receptor blocker (spironolactone) to standard therapy was found to be well tolerated.18 In the RALES trial, an aldosterone receptor blocker reduced morbidity and mortality among patients already on an ACE inhibitor, which emphasises the ineffective suppression of aldosterone production by standard doses of an ACE inhibitor. The gene discussed is ACE; the disease is Hyperkalemia.