Serum IgG2 concentration is associated with Gm-allotypes of IgG2 but not with the R131H polymorphism of human Fc-gamma receptor type IIa.

Serum concentrations of immunoglobulins IgG, IgG1, and IgG2 were determined in 62 Finnish subjects who were also typed for Gm(n) allele of IgG2 and R131 and H131 alleles of the Fcy receptor IIa. Statistically significant G2m-allotype-associated differences in serum concentrations of IgG2 were found; the mean concentration of IgG2 was high in Gm(n)-positive homozygotes (3.9 g/liter) and low in Gm(n)-negative individuals (2.6 g/liter; P = 0.0036), which is in accordance with previous reports. Contrary to an earlier report, no statistically significant R131/ H131-allotype-associated differences were found in serum concentrations of IgG2, not even in the case where the IgG2 concentration was calculated relative to the IgGI or IgG concentration (IgG2/IgG1 or IgG2/IgG). The gene frequencies of R131 and H131 alleles were 0.516 and 0.484, respectively, which did not differ significantly from those reported earlier for Finnish or other Caucasian populations.