WNK2 and hairy cell leukemia: Interestingly, the same amino acid change (V600E) identified in our patient represents a mutational hotspot in melanomas and papillary thyroid cancers, where its oncogenic activity has been extensively documented.15,16 Moreover, dysregulation of the mitogen-activated protein kinase (MAPK) pathways, of which BRAF is a component, was previously implicated in HCL pathogenesis.17 In conclusion, BRAF V600E mutation seems to have an important role in the pathogenesis of HCL if it is not even the disease-defining genetic event.6 9% of patients had BRAF mutation (n=1).