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.

Laboratory Characterizations on 2007 Cases of Monoclonal Gammopathies in East China

“…Occasionally, M protein is associated with malignant epithelial tumors (lungs, gastrointestinal tract, and genitourinary tract) and other diseases (1). One third of M protein positive cases demonstrated a monoclonal Ig in the absence of a progressive disease, called monoclonal gammopathy of undetermined significance (MGUS) (19).…”

Consensus guidelines for the conduct and reporting of clinical trials in systemic light-chain amyloidosis

“…And because monoclonal gammopathies of undetermined significance are increasingly common with age, the possibility that a patient with amyloidosis may have two potential precursor proteins needs to be appreciated. 11 DNA sequencing of genes related to hereditary variants is useful after the type of amyloid has been identified both as confirmatory testing for the patient and as a key screening test for the patient's kindred. 9 Immunoelectron microscopy has proven to be more reliable than immunohistochemistry for typing amyloidosis.…”

The significance of monoclonal gammopathy of undetermined significance

“…Each patient was matched to the control population by age, sex, and date of entry. 11 The median survival of our 1,384 patients from Southeastern Minnesota was 8.1 years, compared to the 11.8 years expected for Minnesota residents of matched age and sex 17 ( Figure 2). Van de Poel et al reported that the long-term survival of 334 patients with MGUS was slightly shorter than the expected survival of age-and sex-adjusted controls.…”