[Monoclonal gammapathy of a familial type. Discovery of myeloma in the sister of a patient suffering from Waldenstrom's macroglobulinemia].

The relatives of a 82 years old female patients with a Waldenstrom Macroglobulinemia were submitted to clinical and hematological investigations. A diclonal gammapathy (IgG kappa and IgG lambda) was found in the sister's serum and was related to a myeloma. A noticiable Bence Jones Proteinuria (light chain of lambda type) was equally found in serum and urines of the propositus brother but without any clinical or hematological evidence of myeloma. The examination of two other sisters of these patients does not reveal any immunological of hematological disorder. This new observation underlines the interest of a systematical investigation in the siblings of the patients with monoclonal gammapathies.