The CXCR4 somatic mutations in WM are identical to the germline variants found in a rare disease called WHIM syndrome (warts, hypogammaglobulinemia, infection, and myelokathexis), thus a mutated CXCR4 is denoted CXCR4WHIM [30, 31]. Here, CXCR4 is linked to WHIM syndrome.