PIK3CD and B-cell chronic lymphocytic leukemia: In addition to genes confirmed to be mutated in previous CLL sequencing studies, such as ATM, CD79B, DDX3X, FBXW7, MYD88, NOTCH1, SF3B1, TP53, XPO [6, 7, 10, 21–23], we chose target genes directly or indirectly involved in the B-cell receptor (BCR) signaling pathway (BTK, MAPK1, PIK3CA, PIK3CD, PTEN, PTPN6).