The most frequent causes of inappropriate RBC transfusion were: no Hb determination pre-RBC transfusion (n = 317) and among these RBC transfused as a second unit in a single-transfusion episode (n = 260), absence of anemia sings/symptoms (n = 179), and Hb concentration ≥80 g/L (n = 80). This evidence concerns the gene GSTM1 and anemia (phenotype).