Because our aim was to develop a highly accurate RT-MLPA assay, in further analyses, we selected those gene probes that robustly discriminated the mutational subgroups (i.e., WT versus TP53/ATM-mutated samples for cluster I genes and TP53-defective versusATM-defective CLL for cluster II-IV genes). The gene discussed is ATM; the disease is B-cell chronic lymphocytic leukemia.