sIgM levels or signaling and NOTCH1 or SF3B1 mutations in CLL. Associations or correlations of NOTCH1_ΔCT with sIgM levels or signaling capacity were sought following identification of NOTCH1_ΔCT by ARMS PCR and Sanger sequencing or following determination of NOTCH1_ΔCT allele frequency by digital PCR in the tumor population. (A) Associations NOTCH1_ΔCT with sIgM levels or signaling capacity. (B) Correlation analyses between NOTCH1_ΔCT allele frequency and sIgM expression and signaling was assessed by digital PCR in those cases that scored NOTCH1_ΔCT mutants by ARMS PCR/sequencing. (C) SF3B1 mutational status was determined by HRM-PCR and confirmed by Sanger sequencing. Cases with and without SF3B1 mutation were investigated for association with sIgM expression and sIgM-mediated signaling responses. Horizontal bars indicate mean values. Statistical analyses for associations were performed using the Mann-Whitney test (2 tailed, 95% CI). Statistical analyses for correlations were performed using the Spearman rank correlation test.