Following initial observations of an association between HCN and outcome [8] and both HCN and HCM with severe disease [11] two studies have shown an association between the number of HCM and anaemia and with plasma levels of TNF-α in a univariate analysis [12] and between the number of circulating HCM and a group of 26 children with Hb < 5 g/dL [10]. The gene discussed is GSTM1; the disease is anemia.