ATM mutations reduce both OS and TFS, independently of IGVH status. Patients with CLL with ATM mutations had poorer OS than did patients with CLL with ATM wild-type mutations, and this was more marked in the IGVH mutated (P = .0110) than unmutated (P = .3161) subgroup. The stratified log rank test for both graphs was significant (P < .001), therefore, indicating that ATM mutations reduce survival after adjusting for IGVH status.