A subgroup of MDS, MDS/MPN and acute leukaemia cases are associated with a familial predisposing germ line mutation (e.g. DDX41, CEBPA, GATA2, TP53 and genes involved in bone marrow failure syndromes and telomere biology disorders – see Table 7.03 WHO 2017) [1] and analysis should be performed where appropriate. Here, DDX41 is linked to myeloproliferative neoplasm.