CD8A and rickets: Similarly, hypovitaminosis D is associated with alopecia areata (AA), a chronic T-cell-mediated autoimmune disorder whose pathogenesis involves the loss of immune privilege in hair follicles, driven by autoreactive T cells, mast cells (MCs), CD8+ NKG2D+ cytotoxic T cells, and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway [25].