MGUS is a non-cancerous (benign) condition. Most people with MGUS remain well. However, a small number of people may go on to develop more serious problems, so everyone with the condition has regular tests.
MGUS (monoclonal gammopathy of unknown significance) is a condition where the body makes an abnormal protein, called a paraprotein. These paraproteins are found in the blood and urine when they’re tested.
MGUS is linked to the immune system. The immune system helps the body fight infection and disease. It is made up of organs such as the bone marrow, the spleen, lymph nodes and white blood cells.
MGUS affects plasma cells. Plasma cells are a type of white blood cell that make antibodies to help fight infections. Antibodies are made from a protein called immunoglobulin.
With MGUS, some plasma cells make an abnormally high number of a type of antibody called a paraprotein (or M-protein). This paraprotein doesn't do anything useful, and for most people it isn't harmful.
Although MGUS is not a cancer, people who have it are at slightly higher risk of certain cancers. The two main cancer types people with MGUS are more at risk of developing are myeloma (cancer of the plasma cells) and lymphoma (cancer of the lymphatic system).
These cancers also produce large amounts of paraproteins. Although the levels of paraprotein are raised in MGUS, they're not as high as the levels in people with cancer.
Most people with MGUS remain well and it causes few problems. Because a small number of people may go on to develop cancer, everyone with MGUS has regular checks.