Expanding the Phenotypic and Genotypic Landscape of Autoimmune Polyendocrine Syndrome Type 1

Abstract Context Autoimmune polyendocrine syndrome type 1 (APS-1) is a rare monogenic autoimmune disease caused by mutations in the autoimmune regulator (AIRE) gene and characterized by chronic mucocutaneous candidiasis, hypoparathyroidism, and primary adrenal insufficiency. Comprehensive characterizations of large patient cohorts are rare. Objective To perform an extensive clinical, immunological, and genetic characterization of a large nationwide Russian APS-1 cohort. Subjects and Methods Clinical components were mapped by systematic investigations, sera were screened for autoantibodies associated with APS-1, and AIRE mutations were characterized by Sanger sequencing. Results We identified 112 patients with APS-1, which is, to the best of our knowledge, the largest cohort described to date. Careful phenotyping revealed several additional and uncommon phenotypes such as cerebellar ataxia with pseudotumor, ptosis, and retinitis pigmentosa. Neutralizing autoantibodies to interferon-ω were found in all patients except for one. The major Finnish mutation c.769C>T (p.R257*) was the most frequent and was present in 72% of the alleles. Altogether, 19 different mutations were found, of which 9 were unknown: c.38T>C (p.L13P), c.173C>T (p.A58V), c.280C>T (p.Q94*), c.554C>G (p.S185*), c.661A>T (p.K221*), c.821del (p.Gly274Afs*104), c.1195G>C (p.A399P), c.1302C>A (p.C434*), and c.1497del (p.A500Pfs*21). Conclusions The spectrum of phenotypes and AIRE mutation in APS-1 has been expanded. The Finnish major mutation is the most common mutation in Russia and is almost as common as in Finland. Assay of interferon antibodies is a robust screening tool for APS-1. Studying several typings of a Russian APS-1 cohort, we found wide clinical variation and what to our knowledge were novel components and nine novel mutations in AIRE, p.R257* being the most common.