IL17A and psoriasis: Furthermore, we included three predefined psoriasis-related gene sets as positive controls based on 1) top psoriasis GWAS hits in GWAS Catalog [32], 2) the well-established IL23/IL17 pathway [33, 34], and 3) previously refined psoriasis gene signatures based on differential analysis of transcriptome data (details in Additional file 1: Table S2) [35, 36].