Three genes in the IL-12 signaling pathway, including the intergenic region of IL12A [51, 52], IL-12 receptor B (IL-12RB)-1 [52, 63], and IL-12RB2 [52, 64], were reported to be associated with SSc by GWAS, implying an important role of IL-12-mediated Th1 response in SSc pathogenesis. This evidence concerns the gene IL12A and systemic sclerosis.