Autoimmune polyendocrinopathy candidiasis-ectodermal dystrophy (APECED) is a rare recessively inherited disorder caused by mutations in the AIRE (autoimmune regulator) gene. APECED is characterized by variable combinations of endocrine autoimmune diseases such as Addison's disease, hypoparathyroidism, and type 1 diabetes. The AIRE protein contains motifs suggestive of a transcription regulator and can activate transcription of a reporter gene when fused to a heterologous DNA biding domain. In this article, mutation analyses of over 200 APECED patients published by several laboratories are summarized. To date 42 different mutations have been identified. These mutations include nonsense and missense mutations, small insertions and deletions leading into frame shifts, and splice site mutations. Although mutations are spread throughout the coding region of the gene some hotspots emerge, including the more common and recurrent mutations R257X and 967-979del13bp. Some of the identified mutations have been shown to affect subcellular localization or transactivation properties of the protein, thus providing insights into the functional properties of the predicted protein motifs.