A negative TCF4/IL-17C/ TNF-a/ IL-17A feedback loop decreases TCF4 in an IL-17RA/RE-dependent manner and is further amplified by IL-17C/TCF4 regulation of ZC3H12A and IL-17C regulation of NFKBIZ, resulting in self-sustaining skin inflammation. The gene discussed is TCF4; the disease is dermatitis.