Again, this situation, which is generally well-tolerated by young and healthy patients with active compensating mechanisms for anemia, may be post-operatively complicated by a compromised cardiovascular function, or among patients with sepsis, especially if they are elderly.A recent review40 concludes that due to the tremendous existing variability among patients with respect to delivery and extraction of O2 and cardiac reserve, the critical level of Hb has an individual value as there is no general threshold for RBCT. The gene discussed is GSTM1; the disease is anemia (phenotype).