CDKN2A and B-cell chronic lymphocytic leukemia: Additionally, sequencing data from eight CLL patients who developed resistance to venetoclax revealed recurrent mutations in BTG1 (B cell translocation gene 1), homozygous deletions affecting cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B), mutation in BRAF, and a high-level focal amplification of CD274 (PD-L1) [61].