IL23R and psoriasis: Recent studies have identified PsA-specific loci that begin to explain this increased burden; the presence of glutamic acid at the amino acid position 45 in HLA-B has been shown to be a risk factor for PsA in a psoriasis cohort and our recent Immunochip study confirmed the independent HLA-B association.4 In addition, we reported evidence for a PsA-specific risk locus at chromosome 5q31 and distinct PsA variants at the IL23R locus.5