Purpose of review: Psoriatic arthritis (PsA) has a large genetic component to its heritability, yet investigation into the genetic basis of the disease has lagged behind other rheumatic diseases mainly because of the difficulty in defining classification criteria that would accurately differentiate it from other forms of inflammatory arthritis. However, using a variety of approaches, some confirmed associations have now been identified with PsA susceptibility, making a review of these recent developments timely.
Recent findings: Family studies continue to suggest a large genetic contribution to PsA. Using a candidate gene approach, genes robustly confirmed to be associated with psoriasis vulgaris (PsV) have also been found to be associated with PsA (HLA-Cw*0602, IL23R, IL12B). There is less overlap reported with rheumatoid arthritis (RA) than PsV susceptibility loci but one report suggests that the AFF3 locus may be associated with both RA and PsA.
Summary: Large, well powered genome-wide association studies are currently underway and should provide further insights into the cause of this common arthritic disease over the next few months. The bulk of evidence so far suggests that the genetic factors underlying PsV are also associated with PsA suggesting that future studies of PsV could include patients with PsA.