Have significant positive association with AA; is required for normal cell death of HF and anagen-catagen transition in mice; Injection of TNF-a leads to apoptosis of HF bulb matrix keratinocytes in mice. TNF-a also inhibits HF elongation in a dose-dependent manner. K14-TNF alpha transgenic mice exerted impaired HF growth. The gene discussed is KRT14; the disease is hydrops fetalis.