ARNT and psoriasis: We found that rs3132089, a promoter variant of the HCP5 gene, is highly linked with psoriasis risk SNP rs3134792 (r2 = 0.9253) [18] (Additional file 1: Figure S7a) and located on the binding motif of ARNT and BHLHE40 proteins, which is predicted to result in decreased binding (Additional file 1: Figure S7b).