The authors genotyped three groups of Caucasians: those with PsA, those with psoriasis without arthritis (PsC) and healthy controls for the rs20541 and rs848IL13 single nucleotide polymorphisms (SNPs).
This study confirms that the effect of IL-13 risk locus is specific for PsA, thus highlighting a key biological pathway that differentiates PsA from PsV.
Association with psoriasis and psoriatic arthritis has been found in TNFAIP3 and TNFIP1, ubiquitin ligases in the NF-kappaB pathway, and IL13, a Th2 cytokine.
Similarly, association of the 5q31 gene region encompassing the IL13 gene has been reported with PsA but not psoriasis by one group, but this awaits confirmation in other series.