SF3B1 and cancer: SF3B1 (Splicing Factor 3b, Subunit 1) is the most frequently mutated splicing gene in cancer, recurrently found in hematological malignancies (28% in myelodysplastic syndromes, 15% in chronic lymphocytic leukemia) and 23% of uveal melanoma (UM), the most common primary intraocular tumor in adults [1,2,3,4,5].