IL-17A, which is produced mainly by Th1 and Th1/Th17 cells [18,19], mediates autoimmunity and immune defense against pathogens [20], and is increased in the intestinal mucosa of patients affected by chronic inflammatory bowel disorders, such as celiac disease [21], CD, and ulcerative colitis [22,23]. The gene discussed is IL17A; the disease is celiac disease.