Objective: To investigate whether patients with Addison's disease and polyendocrine syndromes have undiagnosed autoimmune polyendocrine syndrome type I (APS I).
Materials and methods: Forty patients with clinical manifestations resembling APS I and with autoantibodies typical of this condition were screened for Norwegian autoimmune regulator (AIRE) gene mutations.
Results: A 30-year old man who had developed Addison' s disease at the age of 12, but had no other components of APS I, was homozygous for the 1094-1106 deletion mutation in exon 8 of the AIRE gene, the most common mutation found in Norway.
Conclusions: APS I patients with milder and atypical phenotypes are difficult to diagnose on clinical grounds. Autoantibody analysis and mutational analysis of AIRE may therefore be helpful modalities for identifying these individuals.