Lessons from prospective longitudinal follow-up of a French APECED cohort.

BACKGROUND:APECED syndrome is a rare disease caused by biallelic mutations of the AIRE gene, usually presenting with the triad "hypoparathyroidism-adrenal failure-chronic mucocutaneous candidiasis (CMC)" and non-endocrine manifestations. The aim of this study was to determine the molecular profile of the AIRE gene, the prevalence of rare manifestations and to characterize immunological disturbances in a French cohort. PATIENTS AND METHODS:A national, multicenter prospective observational study to collect genetic, clinical, biological and immunological data (NCT03751683). RESULTS:25 patients (23 families) were enrolled. Eleven distinct AIRE variants were identified, two of which were not previously reported: an intronic variant, c.653-70G > A, and a c.1066del (p.Arg356GlyfsX22) variant (exon 9). The most common was the Finnish variant c.769C > T (16 alleles), followed by the variant c.967_979del13 (15 alleles), which seemed associated with a less severe phenotype. 17/25 patients were homozygote. The median number of clinical manifestations was seven; 19/25 patients presented with the hypoparathyroidism-adrenal failure-CMC triad, 8/13 showed pulmonary involvement, 20/25 had ectodermal dystrophy, 8/25 had malabsorption, and 6/23 had asplenia. Fifteen out of 19 patients had NK cell lymphopenia with an increase in CD4+ and CD8+ T lymphocytes and an age-dependent alteration of B lymphocyte homeostasis compared with matched controls (p < 0.001), related to the severity of the disease. All tested sera (n = 18) were positive for anti-interferon-α, 15/18 for anti-interleukin-22 antibodies, and 13/18 for anti-interleukin-17F antibodies, without clear phenotypic correlation other than with CMC. CONCLUSION:This first prospective cohort showed a high AIRE genotype variability, with two new gene variants. The prevalence of potentially life-threatening non-endocrine manifestations, was higher with systematic screening. These manifestations could, along with age-dependent B-cell lymphopenia, contribute to disease severity. Systematic screening for all the manifestations of the syndrome would allow earlier diagnosis, supporting vaccination, and targeted therapeutic approaches.