SF3B1 and B-cell chronic lymphocytic leukemia: In the early stages of myelodysplastic syndromes (MDS) and chronic lymphocytic leukemia (CLL), AS mechanisms often undergo mutations, thus highlighting their importance to cell function.277–279 Abnormalities in AS are primarily attributed to genetic changes that affect AS-related RBPs.280 Mutations most commonly occur in SF3B1, SRSF2, ZRSR2, and U2AF1.