ABSTRACT
Monoclonal gammopathies are disorders characterized by a monoclonal protein (M-protein) detected in the serum or urine by electrophoresis. The M-protein is produced by monoclonal plasma cells in the bone marrow. Multiple myeloma (MM) is the malignant expression of an IgG, IgA, IgD, IgE, or free light-chain monoclonal gammopathy. Marrow plasma cells accumulate and patients die of progressive disease related to bone destruction, renal failure, anemia, infection, or bleeding. Multiple myeloma has a clinically benign precursor condition termed monoclonal gammopathy of undetermined significance (MGUS). Patients are typically asymptomatic and have stable M-protein measurements. The term MGUS has been adopted because approximately 1% of patients per year develop a serious disease, such as multiple myeloma or a related disorder.
