Identification of the somatic C1013G/CXCR4 variant in WM patients. (A) Primary WM samples harboring the C1013G/CXCR4 variant present with higher CXCR4 surface expression compared with wild-type (WT) primary WM samples, as shown by flow cytometry on CD19⁺ BM-derived WM cells. (B) The C1013G/CXCR4 variant is present in lung and kidney tissues of patients with extramedullary WM disease. The variant has been detected by ASO-PCR using genomic DNA. RFI, relative fluorescence intensity.