SAMHD1 somatic mutations have been identified in several human cancers, including chronic lymphocytic leukemia (CLL) [11, 13, 16], myeloma [18], breast cancer [17], lung carcinoma [14], colon and rectal cancer [17, 19, 58], pancreatic cancer [12], and glioblastoma [15]. Here, SAMHD1 is linked to B-cell chronic lymphocytic leukemia.