Prevalence of monoclonal gammopathy of undetermined significance: study of 52,802 persons in Nagasaki City, Japan.
OBJECTIVE
To assess the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in a large Japanese population.


METHODS
From October 1, 1988, to March 31, 2004, a total of 52,802 (of 71,675) Japanese survivors of the atomic bomb explosion in Nagasaki City, Japan, were screened for M protein. The youngest participant was 42.3 years as of October 1, 1988. A 2-step screening was performed with a serum protein electrophoresis followed by immunoelectrophoresis and a quantitative determination of serum concentration of immunoglobulins. Twenty-one patients who were diagnosed for the first time at the time of screening as having multiple myeloma and Waldenström macroglobulinemia were excluded from analyses. Age- and sex-specific prevalence rates of MGUS were calculated.


RESULTS
Monoclonal gammopathy of undetermined significance was identified in 1088 of the 52,781 study participants. The overall prevalence of MGUS was 2.1% (95% confidence interval [CI], 1.9%-2.2%) in the total population screened and 2.4% (95% CI, 2.0%-2.6%) in those 50 years or older. The prevalence was significantly higher in men than in women (2.8% vs 1.6%; age-adjusted odds ratio, 2.0; 95% CI, 1.8-2.3; P less than .001). In both sexes, the prevalence rose with increasing age from 1.0% in participants aged 42 to 49 years, 1.9% in those 50 to 59 years, 2.6% in those 60 to 69 years, and 3.0% in those 70 to 79 years, to 4.4% in those 80 years and older. The heavy chain isotypes of immunoglobulin were IgG in 73.6% of patients, IgA in 17.7%, IgM in 7.5%, and oligoclonal gammopathies in 1.1%.


CONCLUSIONS
The prevalence of MGUS is lower in this Japanese population than that reported in Western countries among people older than 60 years, especially among women.
Department of Hematology and Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, 852-8523, Japan. masakoiw@nagasaki-u.ac.jp
Masako
M
Iwanaga
Masuko
M
Tagawa
Kunihiro
K
Tsukasaki
Shimera
S
Kamihira
Masao
M
Tomonaga
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005107:Explosions; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D054043:Nuclear Weapons; D010265:Paraproteinemias / Q000175:diagnosis / Q000453:epidemiology*; D015995:Prevalence; D017678:Sex Distribution; D017741:Survivors / Q000706:statistics & numerical data; D014504:Urban Health