Aplastic anaemia (AA) is a rare bone marrow failure (BMF) disorder characterized by pancytopenia and a hypocellular bone marrow. AA is commonly acquired, immune mediated, and idiopathic in nature. Activated autoreactive, cytotoxic CD8+ T cells are present but recent work has shown that CD4+ T cells appear to be more important in the pathogenesis of acquired AA. The immune nature of acquired AA provides the rationale for one of the treatment options, namely immunosuppressive therapy. First-line treatment of acquired AA is either immunosuppressive therapy with antithymocyte globulin and ciclosporin or allogeneic haematopoietic stem cell transplantation (HSCT). Both modalities offer excellent survival. Patients treated with immunosuppressive therapy are at later risk of relapse and clonal evolution to myelodysplastic syndrome and acute myeloid leukaemia, so require long-term follow-up. HSCT, if successful, is curative, but risks include graft rejection, infections, and graft-versus-host disease (GVHD); recent changes to the transplant conditioning regimen have reduced the GVHD risk. The inherited forms of AA include Fanconi’s anaemia, a disorder of DNA repair, dyskeratosis congenita, a disorder of telomere maintenance, and Shwachman–Diamond syndrome, one of the so-called ribosomopathies characterized by defective ribosomal biogenesis. Pure red cell aplasia (PRCA) is a form of BMF characterized by severe anaemia with reticulocytopenia and reduced erythroid progenitors in the bone marrow. PRCA most commonly is an acquired disorder and immune mediated, and often occurs in association with a wide range of conditions. Diamond–Blackfan anaemia, an inherited form of PRCA, is another example of a ribosomopathy, and is caused by mutations in one of many ribosomal protein genes, resulting in haploinsufficiency.
Clonal hematopoiesis in adult pure red cell aplasia