ATM and B-cell chronic lymphocytic leukemia: A recent whole-genome sequencing study identified two types of driver mutations in CLL, ones which appear as early events and were found as predominantly clonal (e.g., heterozygous 13q deletion, trisomy 12 or MYD88, and NOTCH1 mutations), whereas others appear later in the course of the disease, as secondary events, and were found mainly subclonal (e.g., TP53, ATM, SF3B1 mutations, and homozygous 13q deletion) [34].