Prevalence of Monoclonal Gammopathy of Undetermined Significance Among Men in Ghana

Abstract

To determine the prevalence of monoclonal gammopathy of undetermined significance (MGUS), a precursor of multiple myeloma (MM), in Ghanaian men vs white men and to test for evidence to support an underlying race-related predisposition of the 2-fold higher prevalence of MGUS in African Americans vs whites. Between September 1, 2004, and September 30, 2006, 917 men (50-74 years) underwent in-person interviews and physical examinations. Serum samples from all participants were analyzed by electrophoresis performed on agarose gel; any serum sample with a discrete or localized band was subjected to immunofixation. Age-adjusted and standardized (to the 2000 world population) prevalence estimates of MGUS and 95% confidence intervals (CIs) were computed in the Ghanaian men and compared with MGUS prevalence in 7996 white men from Minnesota. Associations between selected characteristics and MGUS prevalence were assessed by the Fisher exact test and logistic regression models. Of the 917 study participants, 54 were found to have MGUS, yielding an age-adjusted prevalence of 5.84 (95% CI, 4.27-7.40) per 100 persons. No significant variation was found by age group, ethnicity, education status, or prior infectious diseases. The concentration of monoclonal immunoglobulin was undetectable in 41 (76%) of the 54 MGUS cases, less than 1 g/dL in 10 patients (19%), and 1 g/dL or more in only 3 patients (6%). Compared with white men, the age-adjusted prevalence of MGUS was 1.97-fold (95% CI, 1.94-2.00) higher in Ghanaian men. The prevalence of MGUS in Ghanaian men was twice that in white men, supporting the hypothesis that race-related genetic susceptibility could explain the higher rates of MGUS in black populations. An improved understanding of MGUS and MM pathophysiology would facilitate the development of strategies to prevent progression of MGUS to MM.