In the subgroup of CLL, patients treated with BTK inhibitors (HR 5.54 (95% CI 1.21–24.49; p = 0.027)) and chemotherapy (HR 5.54 (95% CI 1.21–24.49) p = 0.027) had a higher risk for severe infections. This evidence concerns the gene BTK and B-cell chronic lymphocytic leukemia.