There are no known causes to multiple myeloma.
It is not completely understood how a plasma cell can be transformed into a myeloma cell. Many gene transformations (mutations) are present in a myeloma cell. Many of the transformations involve genes that are “recipes” for parts of the immunoglobulin molecule and/or proteins that are important for cell growth/cell diffentiation or cell death. These mutations take place in a fully specialized cell (plasma cell) and myeloma is therefore not inheritable in the usual meaning of the word. However, there are indications of some overrepresentation of myeloma and related diseases in the closest family. This disposition cannot be tested for. It is possible that all factors giving rise to mutations (for example ionizing radiation) may contribute to the development of myeloma. Several mutations are probably a prerequisite for the development of a plasma cell into a myeloma cell
The risk for MGUS (monoclonal gammopathy of undetermined sigificance) progrediating to active multiple myeloma is about 1% annually.
The only known risk factor for developing multiple myeloma is the serum M-protein level. The risk percentage in a period of 10 years approaches the same M-protein level measured in g/l (for example 20 g/l poses a risk equivalent to 20%).