In fact, when analyzing the literature retrospectively, our patient had all the recognized risk factors for postoperative anemia requiring postoperative transfusion of packed red cells: blood transfusion rates after total shoulder arthroplasty vary between 4.5% et 43%, and the main proven risk factors are preoperative anemia with Hb < 109 g/L (for our patient the intensive care unit assessment showed a hemoglobin of 108 g/L), and a total intraoperative blood loss (right and left shoulder together) >300 ml (for our patient estimated blood loss was 500 ml). Here, GSTM1 is linked to anemia (phenotype).