[Clonal hematopoiesis in aplastic anemia]

Aplastic anemia (AA) is an autoimmune-mediated bone marrow failure syndrome. While AA is not a malignant disease, clonal hematopoiesis is commonly detected via next-generation sequencing and single nucleotide polymorphism (SNP) array. Clonal hematopoiesis in AA has been confirmed by the detection of classic X chromosome skewing, PNH clones, UPD6p, and various mutations. The most frequent genetic events in AA are UPD6p and somatic mutations in BCOR/BCORL1, PIGA, DNMT3A, and ASXL1. While some mutations are common between patients with AA and healthy elderly donors, UPD6p and PIGA mutations are specific to clonal cells in AA, which need to manage their highly autoimmune extrinsic environment. During the evolution of AA into myelodysplastic syndrome (MDS), additional genetic events are frequently acquired that provide MDS cells with intrinsic survival benefits. Hematopoietic cells in AA appear to achieve clonal expansion by their escape from recognition and cytotoxicity by CD8 T-cells, accounting for the distinct landscape of genetic events observed in AA.