Triple A syndrome is caused by mutations in AAAS, a new WD-repeat protein gene

Abstract

The triple A syndrome (MIM 231550) is a rare autosomal recessive disorder characterized by adrenal insufficiency, achalasia and alacrima. The frequent association with a variety of neurological features may result in a severely disabling disease. We previously mapped the syndrome to a 6 cM interval on chromosome 12q13 and have now refined the critical region to 0 cM between KRT8 and D12S1651. Overlapping bacterial artificial chromosome (BAC) sequences of a high resolution BAC/P1-derived artificial chromosome (PAC) contig were screened for gene content and a novel gene encoding a 546 amino acid polypeptide was identified. In nine triple A syndrome patients eight different homozygous and compound heterozygous mutations were found in this gene, most of them leading to a truncated protein suggesting loss of function. RNA blotting experiments revealed marked expression in neuroendocrine and gastrointestinal structures, which are predominantly affected in triple A syndrome, supporting the hypothesis that mutations in this triple A syndrome gene (AAAS) are responsible for the disease. The predicted protein belongs to the family of WD repeat-containing proteins which exhibit a high degree of functional diversity including regulation of signal transduction, RNA processing and transcription.