DQCAR microsatellite polymorphism and susceptibility to rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease associated with HLA-DR genes that share a five amino acid sequence motif, QKRAA or QRRAA, from position 70 to 74 in the third hypervariable region of the DRbeta1 molecule. Since the associations between DRB1 genes and susceptibility to RA are incomplete, in this study we examined the CA repeat polymorphic marker DQCAR, located between DQA1 and DQB1 genes, alleles in 98 adult patients with seropositive RA and 100 normal healthy controls. The prevalence of the DQCAR 117 allele was significantly higher in RA patients as compared to normal controls. On the other hand, the frequency of DQCAR 99 was lower in patients than in normal subjects. Analysis of the data suggested that DRB1 genes sharing the QKRAA/QRRAA epitope have the primary association with disease susceptibility and DQCAR alleles do not provide an additional risk for the development of RA.