HOXA9 and myeloproliferative neoplasm: The importance of HOXA9 in AML has been widely explored; however, this has mainly focused on specific AML subtypes such as MLL-rearranged leukaemia18 and NUP98-HOXA9 induced leukaemia19, while its role in other blood malignancies such as MPN or other AML subtypes is poorly characterised.