title: Monoclonal gammopathies of undetermined significance: a review.
abstract: Monoclonal gammopathy of undetermined significance (MGUS) denotes the presence of a monoclonal protein (M-protein) in patients without evidence of multiple myeloma (MM), macroglobulinemia, amyloidosis (AL), or a related plasma cell proliferative disorder. MGUS is found in approximately 3% of persons older than 70 years and in about 1% of those older than 50 years. In a series of 1384 patients from south-eastern Minnesota in whom MGUS was diagnosed at Mayo Clinic from 1960 through 1994, the risk of progression was 1% per year. Patients were at risk of progression even after 25 years or more of a stable monoclonal gammopathy. The risk of development of MM was increased by 25-fold, the risk of macroglobulinemia was 46-fold, and the risk of primary AL was 8.4-fold when compared with a similar population (Surveillance, Epidemiology and End Results). The concentration of the serum M-protein was the major independent predictor of progression. Patients with an immunoglobulin M (IgM) or an IgA monoclonal gammopathy had a higher risk of progression than those with an IgG monoclonal gammopathy. The presence of a urine M-protein or the reduction of one or more uninvolved Igs was not a risk factor for progression. MGUS may be associated with many different disorders, including lymphoproliferative diseases, leukemia, connective tissue disorders, dermatologic diseases, and neurologic disorders.
authors.affiliation: Division of Hematology and Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA. kyle.robert@mayo.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kyle
authors.forename: S Vincent
authors.initials: SV
authors.lastname: Rajkumar
mesh_terms: D003937:Diagnosis, Differential; D018450:Disease Progression; D006801:Humans; D009389:Neovascularization, Pathologic; D010265:Paraproteinemias / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors