TY - JOUR TI - Hyperphosphorylated paratarg-7: a new molecularly defined risk factor for monoclonal gammopathy of undetermined significance of the IgM type and Waldenstrom macroglobulinemia AU - Grass, Sandra AU - Preuss, Klaus-Dieter AU - Wikowicz, Alexandra and AU - Terpos, Evangelos AU - Ziepert, Marita AU - Nikolaus, Diana AU - Yang, Yin AU - and Fadle, Natalie AU - Regitz, Evi AU - Dimopoulos, Meletios A. and AU - Treon, Steven P. AU - Hunter, Zachary R. AU - Pfreundschuh, Michael JO - Blood advances PY - 2011 VL - 117 TODO - 10 SP - 2918-2923 PB - AMER SOC HEMATOLOGY SN - null TODO - 10.1182/blood-2010-09-306076 TODO - null TODO - We recently described paratarg-7 (P-7), a protein of unknown function, as the target of 15% of immunoglobulin A (IgA) and IgG paraproteins in monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma. To determine the frequency of P-7 as a paraprotein target in IgM-MGUS and Waldenstrom macroglobulinemia (WM), sera from patients with IgM-MGUS/WM were tested for reactivity with recombinant P-7 by enzyme-linked immunoabsorbent assay. The specificity of the paraprotein-mediated reaction was shown by absorption studies and cloning of the respective B-cell receptor. The paraproteins of 18 (9 WM and 9 IgM-MGUS) of 161 patients (11%) reacted with P-7. Isoelectric focusing and phosphatase treatment showed that P-7 was hyperphosphorylated (pP-7) in all patients with an anti-P-7-specific IgM paraprotein tested. Because only 4 of 200 healthy controls (2%) were carriers of pP-7, pP-7 carrier state is associated with a significantly increased risk (odds ratio = 6.2; P = .001) for developing IgM-MGUS/MW. Family analyses showed that the pP-7 carrier state is inherited as a dominant trait. After IgA/IgG-MGUS and multiple myeloma, IgM-MGUS/WM is the second neoplasia associated with pP-7 carrier state. The dominant inheritance of pP-7 explains cases of familial IgM-MGUS/WM and enables the identification of family members at increased risk. (Blood. 2011;117(10):2918-2923) ER -