Subsequently, additional JAK inhibitors, including tofacitinib (a pan JAK inhibitor with greater selectivity for JAK1/JAK3), baricitinib (BARI, a JAK1/JAK2), upadacitinib (JAK1), filgotinib (JAK1), pacritinib (JAK2), and abrocitinib (JAK1), have been approved for treating various inflammatory and autoimmune diseases, such as atopic dermatitis, psoriasis, alopecia areata, psoriatic arthritis, juvenile idiopathic arthritis, rheumatoid arthritis, ankylosing spondylitis, ulcerative colitis, and most recently, vitiligo [9,10,11]. Here, JAK2 is linked to juvenile idiopathic arthritis.