GFI1B and myeloproliferative disorder: Consistent with the importance of the GFI1B downstream sequence in its regulation and the role of this gene in blood cancer, a genome-wide association study identified a C>G variation in this region (rs621940, g.135870130C>G in GRCh37/hg19), which is associated with MPN patients and normal carriers of JAK2 V617F, but not with normal unmutated individuals (p = 1.9 × 10−7) (54).