Recent studies demonstrated that infiltration of cytotoxic subset of CD8+NKG2D+ T cells around human AA hair follicles along with a concomitant upregulation in the follicle itself of the “danger signals” ULBP3 3 and MICA 4, two NKG2D ligands (NKG2DLs) due to autoimmunity activation is the major etiology of AA. This evidence concerns the gene KLRK1 and Autoimmunity.