Investigating the genetic background of STAT4 regulation, very recent studies suggested a significant association of genetic variants in the STAT4 gene on chromosome 2q with systemic lupus erythematosus (SLE) and rheumatoid arthritis [23], [27], [32], [33] as well as Sjögren's disease (SD), [34] systemic sclerosis, [23], [35] psoriasis [36] and also type-1 diabetes, [37] thus indicating common genetic and molecular pathways in multiple autoimmune diseases. This evidence concerns the gene STAT4 and psoriasis.