CLL samples with clear genotypic characteristics (i.e., biallelic defects) were assigned with a high degree of confidence to one of the three categories with sensitivities of 93%, 100% and 78% for TP53/ATM WT, biallelic TP53-defective and biallelic ATM-defective samples, respectively. Here, ATM is linked to B-cell chronic lymphocytic leukemia.