IL4 and Behcet disease: In addition to HLA-B51 as the strongest genetic factor for BD, which explains 20% incidence of BD [43, 44], GWAS and subsequent genetic studies have identified a number of non-HLA potent loci for the susceptibility and organ damages of this disease, such as cytokines (IL-4 [45], IL-6 [46], IL-10 [7, 40], CCL2 [47, 48], TNF-α [49]), ERAP1 [40], UBASH3B [50, 51], STAT4 [52].