DNA polymorphism of immunoglobulin kappa confers risk of rheumatoid arthritis

Abstract

To examine the hypothesis that a hereditary factor linked to the immunoglobulin kappa constant segment (C_κ) contributes to risk of rheumatoid arthritis (RA), white persons with RA were examined for Sac I restriction site polymorphisms. RA patients were more likely to have the 5/5‐kb C_κ genotype than white control subjects (relative risk 2.8, P < 0.02). A subgroup of RA patients who were positive for serum rheumatoid factor had a relative risk of 2.4 (P < 0.05). The subgroup without serum rheumatoid factor had an even higher relative risk of 9.7 (P < 0.05). The results suggest that immunoglobulin kappa is an important component in the genetic predisposition toward RA.