IFN-γ renders the hair bulb susceptible to cytotoxic attacks that destroy anagen epithelial cells, as well as stem cells in the outer root sheath during anagen (106), while sparing the stem cells residing in the bulge region (105)—a pattern reminiscent of the immune-mediated follicular damage observed in alopecia areata, where bulge stem cells remain intact (4, 5). The gene discussed is IFNG; the disease is alopecia areata.