Abstract: Acquired aplastic anemia (AA) is an immune-mediated bone marrow failure disease. Clonal hematopoiesis can be seen in hematopoietic stem cells in more than 70% of AA patients. Common somatic mutations such as the deletion of PIGA gene and HLA allele in AA may be closely related to its immunopathological mechanism. Older age, shortened telomeres in leukocytes and HLA class Ⅰ risk alleles in AA may promote clonal evolution. The course, gene mutation and cytogenetic abnormalities of AA play a key role in the transformation of AA to myelodysplastic syndrome (MDS). Based on the latest research progress of AA cloning evolution and the report of the 60th Annual Conference of American Society of Hematology, this paper reviews the origin, selection and evolution of AA clone. The influencing factors of AA clone evolution and the risk factors of AA transforming into MDS are discussed emphatically.

Key words: anemia, aplastic, HLA antigens, alleles, telomere, clonal evolution