To identify cryptic 3’SSs with relatively high PSI values in the SF3B1 mutant versus wild-type samples, we searched for cryptic 3’SSs that were 1) used more than 50% of the time in the CLL SF3B1 mutants; 2) used less than 20% of the time in wild-type samples; and 3) had an average coverage of at least 30 junction-spanning reads in the mutant samples. This evidence concerns the gene SF3B1 and B-cell chronic lymphocytic leukemia.