Immunoglobulin analysis in families of macroglobulinaemia patients.

Serum electrophoresis and quantitative determination of serum immunoglobulin levels were performed in 353 relatives of twenty-three patients with macroglobulinaemia. The immunoglobulin levels in the relatives were compared with the levels found in a random sample of the total population of a rural district; the validity of this comparison is discussed. The number of abnormalities in the electropherograms is discussed in relation to the data in the literature. Only the number of abnormalities, both quantitative and qualitative, found in the IgM class was higher than would be expected in the general population, if only chance were involved. Abnormalities also occurred in the IgG and IgA classes, but their number is not higher than expected, thus indicating that they are not associated with the disease in the propositus. Several possible explanations for the concentration of IgM abnormalities in families of patients with macroglobulinaemia are discussed.