In addition, S34 and Q157 do not cooperate with the same mutations in MDS (e.g., BCOR with S34 > Q157 and ASXL1 with Q157 > S34),36 and this could impact mutation-associated phenotypes in patients.15,37 Finally, U2AF1 hotspot mutation phenotypes could be influenced by the order of cooperating gene mutation acquisition (i.e., U2AF1 mutation occurring before or after a cooperating gene mutation) or the presence of hematopoietic stressors, requiring future experiments. Here, U2AF1 is linked to myelodysplastic syndrome.