CD40LG and plasma cell myeloma: We sequenced the MYD88 gene (OMIM: 602170) using HaloPlex targeted capture on an Illumina MiSeq, in 41 cases with IgM monoclonal component (27 WM, 14 IgM MGUS), 5 additional family members with IgG monoclonal component or full-blown multiple myeloma (4 IgG-MGUS, 1 IgA-myeloma), and 2 healthy individuals, from 20 unrelated families with at least two cases of WM or IgM MGUS (S1 Table and S1 Fig).