Evaluation of: Liu Y, Helms C, Liao W et al. A genome-wide association study of psoriasis and psoriatic arthritis identifies new disease loci. PLoS Genet 4, e1000041.
Genome-wide association scans have delivered on their promise of revealing susceptibility polymorphisms underlying common diseases. This comprehensive psoriasis study reports confirmation of previously identified genes, HLA-C, IL12B and IL23R, identifies several novel psoriasis loci and is the first to report psoriatic arthritis association on a genome-wide scale. Along with other recent studies, this work gives further evidence that IL-23 mediated signaling is a key component of both psoriasis and psoriatic arthritis pathogenesis. Importantly, this study provides evidence of a single SNP, 35kb upstream of HLA-C, which is stronger than Cw*0602 – the variant traditionally attributed to the MHC-linked psoriasis-susceptibility effect. Within this region, they also discover an independent SNP with very strong predisposing effects. SNPs in the COG6 region and the USP8-TNFAIP8l3 region are among novel psoriasis associations reported. In addition, a region showing linkage on chromosome 1q demonstrated association in the epidermal differentiation complex. Four SNPs over a 439kb region on chromosome 4q27, where KIAA1109, ADAD1, and two cytokine-encoding genes (IL2 and IL21) reside, exhibit intriguing correlation with psoriatic arthritis although the signal strength is moderate. These results, while still preliminary, may substantially expand our knowledge of psoriasis and psoriatic arthritis genetics – opening new avenues of chronic inflammatory disease research.
Available at: http://works.bepress.com/steve_schrodi/34/