There have been 94 reported cases of JAK2r in ALL (Table 3), in comparison, only four cases of JAK2r have been reported in MPNs, including BCR::JAK2, PCM1::JAK2 (pericentriolar material 1/JAK2), RPN1::JAK2 (ribophorin 1/JAK2) and PEX14::JAK2 (peroxisomal biogenesis factor 14/JAK2) (Murati et al., 2005; Mark et al., 2006; Elnaggar et al., 2012; Lundberg et al., 2014; He et al., 2016; Levavi et al., 2019). Here, BCR is linked to acute lymphoblastic leukemia.