NOTCH1 and B-cell chronic lymphocytic leukemia: In particular, the latter studies report a detection limit of 0.03% for variant allele frequency, way lower than the NGS limit of about 0.3–1.3 [11,126]; in parallel, they have also suggested that NOTCH1 delCT mutations may be present in a greater fraction of CLL cells, ranging from 18.6–25% [124,125] up to 55% in CLL cases with trisomy 12.