In addition to NOTCH1, mutations in the NOTCH1 regulatory pathway including SPEN have been described in a limited number of CLL cases and others have suggested that these mutations are also associated with adverse patient outcomes Methods: In this study, 1617 CLL cases were assessed using targeted sequencing and a 29-gene panel and the results were correlated with prognosis. The gene discussed is NOTCH1; the disease is B-cell chronic lymphocytic leukemia.