[Genetic abnormalities in bone marrow failure]

Bone marrow (BM) failure is a condition characterized by peripheral pancytopenia resulting from decreased hematopoiesis in the BM. It includes congenital disorders such as Fanconi anemia (FA), as well as acquired conditions such as acquired aplastic anemia (AA), myelodysplastic syndrome (MDS), and paroxysmal nocturnal hemoglobinuria (PNH). AA presents with pancytopenia and BM hypoplasia, primarily triggered by an autoimmune mechanism involving T cells that damage hematopoietic stem cells (HSCs). Genomic investigations utilizing next-generation sequencing or SNP arrays have revealed that clonal hematopoiesis by HSCs with genetic aberrations, including PIGA, DNMT3A, ASXL1, BCOR/BCORL1, copy-number neutral LOH of chromosome 6p (6pLOH), and somatic mutations in HLA class I alleles are prevalent in AA patients. Recent studies have identified somatic mutations in genes associated with the JAK-STAT and MAPK pathways in T cells of AA patients. Genomic abnormalities in AA differ from those observed in MDS and age-related clonal hematopoiesis. Notably, the presence of PNH-type cells and HLA class I allele-lacking cells represent two major instances of escape hematopoiesis, which indicate the presence of HSCs evading autoimmune T cell attacks. These findings provide crucial insights into the immune pathophysiology of BM failure.