The Autoimmune Regulator is expressed in the thymus. It causes transcription of a wide selection of organ-specific genes. This reduces the threat of autoimmunity occurring by allowing the elimination of autoreactive T cells by the process of negative selection if they are too reactive to self. It is mutated in the rare autoimmune syndrome Autoimmune Polyendocrinopathy Syndrome type 1 (APS-1), also known as Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy (APECED). Disruption of AIRE results in the development of a range of autoimmune diseases, the most common clinical conditions in the syndrome are hypoparathyroidism, primary adrenocortical failure and chronic mucocutaneous candidiasis. AIRE is expressed primarily in the thymus.