Recent studies of chronic lymphocytic leukemia, breast cancer and uveal melanoma using RNA-Seq have shown that SF3B1 mutations are associated with differential exon usage and induce cryptic alternative 3′ splice site selection in these cancers.28 However, a systematic analysis of cryptic splicing abnormalities has not been performed in MDS HSCs. Here, SF3B1 is linked to B-cell chronic lymphocytic leukemia.