The aim of the present study was to investigate Norwegian patients with autoimmune polyendocrine syndrome type I (APS I), with respect to occurrence and clinical presentation, reactivity towards different autoantigenes and mutations in the autoimmune regulator (AIRE) gene.

Twenty Norwegian patients from 15 families with APS I (11 males, nine females; mean age 26 years, range 4–54) were included by contacting all major hospitals in Norway.

Clinical data was collected from both patients and their physicians by the use of questionnaires and patient records. Autoantibodies were analysed using radioimmunoassays based on antigen synthesized by in vitro transcription and translation. AIRE mutations were determined by DNA sequence analysis.

The prevalence of APS I in Norway was estimated to be about 1 : 80 000 individuals. We found about the same distribution of disease characteristics as has been reported in Finnish patients. The diagnosis was delayed in many individuals. In two thirds of the cases, the patients were admitted in Hospital with acute adrenal insufficiency or hypocalcaemic crisis. Forty percent of these patients already had one of the main disease manifestations. Four different mutations in the AIRE gene were found in the Norwegian cohort. A 13‐bp deletion in exon 8 (1085–1097_del) was the most frequent mutation, present in 22/40 (55%) of the alleles. Eighty‐five percent of the patients had either autoantibodies against 21 hydroxylase or aromatic l‐amino acid decarboxylase. Five of eight women (age > 13 years) had ovarian failure, and all of these had antibodies against side‐chain cleavage enzyme (P = 0·0002).

Norwegian patients with APS I clinically resemble patients from Finland and other European countries. The diagnosis APS I must be considered in children and adolescents with chronic mucocutaneous candidiasis, autoimmune adrenocortical failure or hypoparathyroidism in order to avoid fatal complications. Analysis of autoantibodies and mutational analysis of the AIRE gene are valuable diagnostic tools, especially in the early stages of the disease.