RCTs that have evaluated Hb thresholds for transfusion in critically ill patients have consistently found that restrictive transfusion strategies (Hb thresholds between 70 and 90 g/L) are as safe as, or safer than, liberal strategies (thresholds ≥ 90 g/L) [383–387] with the possible exception of patients with acute coronary syndrome. The gene discussed is GSTM1; the disease is acute coronary syndrome.