Rare anti-AnWj autoantibody in a 75-year-old male: Case report and review of the literature.

Although AnWj is a high-frequency red blood cell antigen in the ISBT (International Society of Blood Transfusion) 901 series, with a prevalence exceeding 99% in the general population, anti-AnWj is encountered very rarely. We described a 75-year-old man with idiopathic thrombocytopenic purpura (ITP), coronary artery disease (CAD) status post coronary artery bypass graft (CABG) and recent percutaneous coronary interventions (PCIs), aortic stenosis status post aortic valve replacement (AVR), admitted twice due to bleeding and severe anemia. Immunohematology and serological studies suggested the patient's A-negative blood type with anti-AnWj. Given life-threatening anemia, ischemic risk from recent PCI, absence of compatible units and the autoantibody characteristic of anti-AnWj, the team proceeded with transfusions without matching AnWj antigen after multidisciplinary discussions. Subsequent genotyping demonstrated a wild‑type MAL gene, confirming the presence of auto‑anti‑AnWj. Fortunately, there was no transfusion reaction, including hemolysis, probably due to the autoantibody nature or low titer of anti-AnWj. This case presents clinical challenges when a rare antibody, such as anti-AnWj, is encountered in a critically ill patient requiring transfusion.