For example, four IFN receptor genes (IFNAR1, IFNAR2, IFNGR2, and IL10RB) and two IFN-stimulated genes (MX1 and MX2) are triplicated in Down syndrome, and individuals with Down syndrome exhibit hypersensitivity to type I IFN (IFN-I) [4,6]. The gene discussed is MX1; the disease is Down syndrome.