Certain HLA-B and HLA-C alleles confer susceptibility to PsA among patients with psoriasis and may be used to identify patients with PsC who may develop PsA.

The recurrence risk ratio for both PsA and psoriasis is high in FDRs and siblings of patients with PsA. These results confirm that both PsA and psoriasis have a strong heritable component.

Objective. To investigate the association between potential environmental exposures and the development of psoriatic arthritis (PsA) in patients with psoriasis. Methods. In this case-control study, the cases were patients with recent-onset PsA. The controls were psoriasis patients without arthritis. The occurrence of the following environmental exposures was recorded through a standardized questionnaire: smoking, alcohol consumption, infections, injuries, physically demanding occupational tasks, stressful life events, vaccinations, and female hormonal exposures. The association between each exposure to environmental events and disease status was assessed through logistic regression after adjustment for age, sex, education level, and duration and severity of psoriasis.

Smoking may be inversely associated with PsA among psoriasis patients. This association is not present among HLA-C*06-positive individuals.

PsA patients suffer from more severe subclinical atherosclerosis compared with patients with PsC. This difference is independent of traditional cardiovascular risk factors and correlates with PsA disease duration, more severe skin disease and increased inflammatory markers.