Although it remains unclear whether S100A2 is involved in physiological function in hair follicles, S100A2 is highly expressed in the entire outer-root sheath, whereas its expression is lower in the medulla and cuticle in the bulb [42], suggesting that alopecia areata or other hair-related diseases might also be associated with S100A2-mediated pathogenesis. This evidence concerns the gene S100A2 and alopecia areata.