Recent advances in the genetics of rheumatoid arthritis.

Recent progress in defining the role of genetic factors in rheumatoid arthritis (RA) has been remarkable. Anticyclic citrullinated peptide (anti-CCP) antibody-positive disease appears to be immunogenetically distinct from anti-CCP-negative disease, with the former subgroup primarily responsible for association and linkage with the HLA-DRB1 shared epitope (SE). There is preliminary evidence that non-HLA genes contribute differentially to anti-CCP-positive and negative disease. The phenotypic differences evident in anti-CCP-positive and negative disease suggest a need to reclassify RA based on the presence or absence of this autoantibody. Some recent work also suggests marked interactions between cigarette smoking, anti-CCP antibodies, and the SE, though these relationships may vary across populations. Lastly, a recent single nucleotide polymorphism-based genome-wide linkage analysis of multicase RA families revealed novel genomic regions that likely contain genes that predispose to RA or more specific phenotypes.