<unk>  is characterized by an uncontrolled clonal proliferation of terminally differentiated B lymphocytes. The most commonly associated mutations, based on whole-genome sequencing of 30 patients, are a somatic mutation in MYD88 (90% of patients) and a somatic mutation in CXCR4 (27% of patients). CXCR4 mutations cause symptomatic hyperviscosity syndrome and high bone marrow activity characteristic of the disease. However, CXCR4 mutation is not associated with splenomegaly, high platelet counts, or different response to therapy, questioning the relevance of CXCR4 in treating patients. An association has been demonstrated with the locus 6p21.3 on chromosome 6. There is a two- to threefold increased risk of<unk>  in people with a personal history of autoimmune diseases with autoantibodies, and a particularly elevated risk associated with liver inflammation, human immunodeficiency virus, and rickettsiosis. There are genetic factors, with first-degree relatives of<unk>  patients shown to have a highly increased risk of also developing the disease. There is also evidence to suggest that environmental factors, including exposure to farming, pesticides, wood dust, and organic solvents, may influence the development of<unk> . Genetics Although believed to be a sporadic disease, studies have shown increased susceptibility within families, indicating a genetic component. A mutation in gene MYD88 has been found to occur frequently in patients.<unk>  cells show only minimal changes in cytogenetic and gene expression studies. Their miRNA signature however differs from their normal counterpart. It is therefore believed that epigenetic modifications play a crucial role in the disease. Comparative genomic hybridization identified the following chromosomal abnormalities: deletions of 6q23 and 13q14, and gains of 3q13-q28, 6p and 18q. FGFR3 is overexpressed. The following signalling pathways have been implicated: * CD154/CD40 * Akt * ubiquitination, p53 activation, cytochrome c release * NF-κB * WNT/beta-catenin * mTOR * ERK * MAPK * Bcl-2 The protein Src tyrosine kinase is overexpressed in<unk>  cells compared with control B cells. Inhibition of Src arrests the cell cycle at phase G1 and has little effect on the survival of<unk>  or normal cells. MicroRNAs involved in<unk> : * increased expression of miRNAs-363*, -206, -494, -155, -184, -542–3p. * decreased expression of miRNA-9*. MicroRNA-155 regulates the proliferation and growth of<unk>  cells in vitro and in vivo, by inhibiting MAPK/ERK, PI3/AKT, and NF-κB pathways. In<unk>  cells, histone deacetylases and histone-modifying genes are de-regulated. Bone marrow tumour cells express the following antigen targets CD20 (98.3%), CD22 (88.3%), CD40 (83.3%), CD52 (77.4%), IgM (83.3%), MUC1 core protein (57.8%), and 1D10 (50%).
Waldenström macroglobulinemia
Monoclonal gammopathy of undetermined significance
AL amyloidosis
Fibrin-associated diffuse large B-cell lymphoma
POEMS syndrome
Thymoma with immunodeficiency
Multiple myeloma
Diffuse large B-cell lymphoma