SpA may occur in patients with HS, with the prevalence in this group exceeding that in the general population. The very short time between skin and joint symptom onset in some cases suggests common pathogenic mechanisms underlying HS and SpA.

High anti-CCP2 levels are associated with lung disease in the RA population.

This study provides the 'association and linkage proof' establishing IRF5 as a RA susceptibility gene and the identification of a genetic factor that seems to contribute to the modulation of the erosive phenotype. Further studies are warranted to clarify the role of IRF5 in RA and its subphenotypes.

IRF5 haplotypes are more informative than single markers, suggesting that they could be helpful for risk stratification of SSc patients. Our study provides further evidence of a key role of IRF5 in SSc severity.

No abstract