system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Alleles, Arthritis, Rheumatoid, CD8 Antigens, DNA, Gene Frequency, Genotype, HLA-DR Antigens, Haplotypes, Homozygote, Humans, Immunoglobulin Variable Region, Immunoglobulin kappa-Chains, Polymorphism, Genetic, Risk Factors.
user
Is variable-constant segment genotype of immunoglobulin kappa associated with increased risk for rheumatoid arthritis? Context: To further investigate the association of rheumatoid arthritis (RA) with a particular genotype identified by a restriction site polymorphism near the constant segment of immunoglobulin kappa (C kappa). The frequencies of genomic DNA polymorphisms detected within or near C kappa (the most C kappa-proximal variable segment [V kappa] B3 and a T lymphocyte marker [CD8A]) were determined by Southern blotting and hybridization. The frequencies of coding-region polymorphisms of C kappa (Km allotypes) were determined by amplification by polymerase chain reaction followed by restriction enzyme digestion. Although the frequencies of B3, Km, and CD8A genotypes were not different between RA and normal control populations, more individuals were homozygous for both C kappa and B3 in the RA group (relative risk 2.2, P less than 0.01), especially in the DR4-negative RA subgroup (relative risk 3.9, P less than 0.001).
assistant
The homozygous genotype of an approximately 30,000-base region including the C kappa segment confers an elevated risk for RA, particularly in the DR4-negative subgroup. Final Decision: yes