Detection of Recurrent Mutations in Waldenström's Disease

Plain-language summary

Waldenström's disease (WM) is a rare, low-grade lymphoid hematopathy, accounting for 1 to 2% of malignant hematopathies and mainly affecting the elderly. This disease is characterized by lymphoplasmocyte cells infiltration into the bone marrow and by the production of a monoclonal IgM protein in the serum. This disease is accompanied by clinical manifestations of hepato-splenomegaly, signs of hyperviscosity, peripheral neuropathies and biological signs with the presence of cytopenias and cryoglobulinemia. Some forms present node or splenic involvement. While the asymptomatic form maintains overall survival close to that of the healthy subject, the symptomatic form is subject to frequent relapses and remains incurable. Current recommendations for the diagnosis and monitoring of this disease are based on protein electrophoresis from a blood sample to quantify monoclonal IgM production and a myelogram or bone marrow biopsy showing medullary infiltration by lymphoplasmocytic cells. However, protein electrophoresis is an imprecise examination since it does not quantify tumour B lymphocytes and has limitations, particularly in the case of poorly secreting forms. More than 90% of Waldenström cases have the L265P mutation of the MYD88 gene. Although this mutation is not found only in these diseases, it can help in the diagnosis. Other mutations are also present in this pathology. These mutations can define prognostic factors or possibly make it possible to identify therapeutic targets. The development of new technologies makes it possible, on the one hand, to follow the L265P mutation of MYD88 over time as a marker of response to treatment and, on the other hand, to define these prognostic markers or therapeutic targets. This study will first determine the best method for monitoring the mutation of MYD88. In a second step, the investigators will evaluate the best type of sampling and in particular whether this mutation is present in the blood in order to limit the invasive procedures such as bone marrow sampling can be limited. Finally, the investigators will evaluate the prognostic

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