IgG heavy chain (Gm) allotypes in rheumatoid arthritis and in healthy individuals seropositive for IgM-rheumatoid factor.

The frequencies of Gm allotypes a, x, f, b, g and n have been investigated in classical seropositive rheumatoid arthritis (RA), erosive definite seronegative RA, non-erosive definite RA and in healthy individuals with serum IgM-RF. No differences in the frequencies of these Gm allotypes were found between patients and healthy controls. It is concluded that any possible putative genes outside the HLA region involved in RA are most likely unrelated to the genes coding for the constant regions of IgG heavy (gamma) chains.