Introduction
Aplastic anemia (AA) [1] is a common and potentially
life-threatening condition in children that leads to bone marrow loss.
The two main AA treatment options are hematopoietic stem cell
transplantation (HSCT) and immunosuppressive therapy. However,
immunosuppressive treatment effectiveness is limited due to
non-responsiveness, relapse, and clonal evolution. Therefore, allogeneic
HSCT is recommended as the first-line treatment for patients aged
<40 years with a matched sibling donor (MSD). HSCT [2] is
currently the primary cell treatment used for therapeutic purposes in
both malignant and nonmalignant hematologic disorders. Transplantation
success is influenced by sex, human leukocyte antigen (HLA)
compatibility, donor age, and cytomegalovirus (CMV) status. However, the
effect of ABO compatibility remains debated [3-4]. Particularly, it
is uncertain whether ABO incompatibility affects HSCT outcomes in
high-risk groups, such as patients who have received long-term
transfusion treatment. Existing knowledge about ABO-mismatched
transplantation in pediatric HSCT is mostly based on studies on adults.
Therefore, we investigated the effect of donor–recipient ABO blood type
matching on the outcomes of pediatric patients with severe AA receiving
HSCT. This is the first report to address this specific research
question.