NOTCH1 and B-cell chronic lymphocytic leukemia: The aims of our study were to analyze: a) a c.7541-7542delCT NOTCH1 mutation assay based on ddPCR; b) the NOTCH1mut allelic burden in CLL patients at diagnosis to assess its prognostic role; c) longitudinal ddPCR in a few cases harboring NOTCH1mut (including patients who required therapy and those who were managed with a “watch and wait” approach).