Electrophoresis of serum proteins from a homogeneous population in Brittany: the Bigoudens.

Serum from 408 subjects drawn at random from a population of 29,985 was tested by quantitative electrophoresis and, when a narrow band was detected, by immunoelectrophoresis. Six cases of monoclonal gammapathy (MG) were found, including four with IgMK and two with IgGK. The incidence of MG (1.47%) was not particularly high, but the proportion of IgM (66.67%) was abnormally elevated. This peculiarity does not seem due to the advanced age of the subjects tested (58 +/- 13 years) but might be the result of too much inbreeding until recent years.