The autoimmune polyglandular syndrome type 1 (APS1), also known as autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APS1), is a monogenic autosomal disease with recessive inheritance. It is characterized by chronic mucocutaneous candidiasis, multiple autoimmune endocrinopathies, and ectodermal dystrophies. The defective gene responsible for this disease has been identified and named "autoimmune regulator" (AIRE). The AIRE gene is located on chromosome 21q22.3. At least 45 different disease-causing mutations in AIRE have been discovered. This review summarizes the global distribution of AIRE mutations and the relevance of major mutations to the clinical disorders associated with APS1. We also will review studies on the structure and DNA-binding ability of the AIRE protein and the possible malfunctions of the AIRE protein as a result of major disease-causing mutations.