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Molecular background of polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome in a Polish population: novel AIRE mutations and an estimate of disease prevalence.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal-recessive autoimmune disease caused by autoimmune regulator gene mutations. The aim of this study was to examine the mutation profile of Polish APECED patients, determine the carrier rate of the most frequent mutation(s) and estimate disease prevalence. While studying 14 unrelated patients, we identified three novel mutations (c.1A>T, affecting the start codon; [IVS1 + 1G>C; IVS1 + 5delG], a complex mutation affecting splice site; c. 908G>C, p.R303P, a missense mutation in plant homeodomain (PHD) and three previously reported mutations (c.769C>T, p.R257X; c.967_979del13bp, C322fsX372; c.931delT, p.C311fsX376). Eleven patients had mutations on both chromosomes, whereas in three patients only a single alteration with proven or likely pathogenic effect was detected. The most frequent was the p.R257X mutation (71% of chromosomes); its carriage rate was assessed in the background population. Analysis of 2008 samples showed eight heterozygotes, indicating the frequency of 0.40% (1:250) and the disease prevalence - 1:129,000 (95% confidence interval: 1:555,000 to 1:30,000). Comparison with an epidemiological estimate (1:619,000, derived for women) suggested that in Poland, APECED is underdiagnosed. Among the patients, no genotype/phenotype correlations were found, but we noted that women had earlier onset of hypoparathyroidism (p < 0.02) and were younger at diagnosis (p < 0.05) than men.

Adolescent↗

Investigation of the p.Ser278Arg polymorphism of the autoimmune regulator (AIRE) gene in alopecia areata.

A recent study has suggested that the g.961C >G (p.Ser278Arg) variant of the autoimmune regulator (AIRE) gene contributes to susceptibility to alopecia areata (AA). We attempted to replicate this finding using a case-control sample of Belgian-German origin (273 patients and 283 controls). Despite adequate power, our study results do not support a significant association of the risk allele in our AA patient sample. This remained the case when we stratified our sample according to severity and family history of disease. Our study results do not support the hypothesis that the g.961C >G (p.Ser278Arg) polymorphism of the AIRE gene is associated with an increased risk for AA.

Alleles↗

Polymorphisms at +49A/G and CT60 sites in the 3' UTR of the CTLA-4 gene and APECED-related AIRE gene mutations analysis in sporadic idiopathic hypoparathyroidism.

Autoimmune diseases such as Graves' disease and type 1 diabetes have been linked with +49A/G and CT60 single nucleotide polymorphisms (SNPs) in the 3' UTR of the cytotoxic T-lymphocyte antigen-4 (CTLA-4) gene. Both these SNPs are functionally relevant and linked with T-lymphocyte activation. Hypoparathyroidism is seen in 70% of patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome (APECED). Although calcium sensing receptor autoantibodies (CaSRAb) and generalized activation of T lymphocytes are reported among patients with sporadic idiopathic hypoparathyroidism (SIH), CTLA-4 gene SNPs and APECED-related autoimmune regulator (AIRE) gene mutations have not been assessed in them. We studied lead CTLA-4 gene SNPs and APECED-related AIRE gene mutations in 73 patients with SIH and 114 healthy subjects. The CTLA-4 gene SNPs +49A/G in exon 1, CT60A/G in 3' UTR and -318C/T in the promoter region were genotyped by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) using BstEII, NcoI and MseI endonucleases, respectively. The APECED-related AIRE gene mutations, which is R257X (Finn-major) in exon 6, 4-bp insertion and 13-bp deletion in exon 8, and Iranian Jews population 'Y85C' mutation in exon 2, were studied by PCR-RFLP (Taq-I), PCR and nucleotide sequencing, respectively. CaSRAb were studied by immunoblotting. The frequencies of CTLA-4 A/A(49), A/G(49) and G/G(49) genotypes in the patients (47.9%, 38.4% and 13.7%) and controls (45.6%, 39.5% and 14.9%, respectively) and the frequencies of CT60 A/A, A/G, and G/G genotypes in the patient (42.4%, 37.0% and 20.6%) and the control (38.6%, 40.4% and 21.0%, respectively) groups were not significantly different. The frequencies of various haplotypes including genetic loci +49A/G and CT60 and frequencies of G alleles at these positions were comparable between patient and the control groups and its presence did not correlate with clinical and biochemical indices of the disease. None of the patients had APECED-related AIRE gene mutations. Lack of significant difference in the pattern of CTLA-4 A/G(49) and/or CT60A/G genotypes and absence of common APECED syndrome-related AIRE gene mutations among patients and controls suggest that these sites do not play a role in the development of the SIH.

3' Untranslated Regions↗

Component A2 of the methylcoenzyme M methylreductase system from Methanobacterium thermoautotrophicum.

Component A2 of the methylcoenzyme M methylreductase system of Methanobacterium thermoautotrophicum has been purified 370-fold by liquid chromatography. Homogeneity was obtained by anaerobic preparative polyacrylamide gel electrophoresis. Component A2 is a colorless, air-stable protein consisting of a single polypeptide as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The relative molecular mass of the native protein was determined by high-performance, size exclusion chromatography to be Mr 52,000; on sodium dodecyl sulfate-polyacrylamide gel electrophoresis a value of Mr 59,000 was obtained. When cell extract was subjected to N6-ATP-agarose affinity chromatography the methylcoenzyme M methylreductase system was resolved into two fractions; one of them was component A2. This work provides a new operational definition for component A2, i.e., its characteristic chromatographic behavior on N6-ATP-agarose. However, its functional definition is its ability to reconstitute the methylreductase activity with components A1, A3, and C. Several attempts to assign a role to component A2 are reported.

Chromatography, Affinity↗

[AIRE gene mutation in polyglandular syndrome type 1].

Autoimmune polyglandular syndrome type 1 (APS-1) is an autosomal recessive disorder characterized by chronic mucocutaneous candidiasis, autoimmune hypoparathyroidism, and primary adrenal insufficiency. It has recently been associated with mutations of a single gene found on chromosome 21, designated AutoImmune Regulator (AIRE). We report two patients with APS-1 referred to our hospital for evaluation. The first patient was an 11-year-old girl with hypoparathyroidism, infectious or immunological malabsorption, and autoimmune hepatitis. Hypoparathyroidism associated with other processes with a probable autoimmune origin suggested APS-1. Genetic study was performed revealing deletion of 13 base pairs in exon 8 of the AIRE gene. The second patient was a 17-year-old girl with autoimmune hepatitis, hypoparathyroidism, mucocutaneous candidiasis, nail dystrophy, and obliterating bronchiolitis with a probable autoimmune origin. We suspected APS-1 and genetic study was performed. The only finding was an AIRE gene polymorphism. In conclusion, the presence of a single disease criterion is sufficient to suspect APS-1 and to indicate genetic study. Further studies are required to confirm the involvement of other genes in the development of this disease.

Adolescent↗

Autoimmunity: basic mechanisms and implications in endocrine diseases. Part I.

Autoimmunity implies disturbances at several levels of the immune control. Self-tolerance and discrimination between self and non-self synergize to avoid the development of autoimmunity. Negative selection in the thymus, the transcription factor AIRE, CD4+CD25+ regulatory T cells, and dendritic cells cooperate to produce and maintain tolerance. Cytokines modulate deriving immune processes and influence the local micro-environment. Multiple mechanisms are involved in tolerance breakdown: genetic factors (major histocompatibility complex haplotypes, polymorphisms in the cytotoxic T lymphocyte antigen gene and epigenetic alterations), environmental factors (mainly infections), impaired apoptosis, and the emergence of autoreactive naive lymphocytes. These events may be involved in the pathogenesis of endocrine diseases at several levels.

Animals↗

NF-kappaB2 is required for the establishment of central tolerance through an Aire-dependent pathway.

NF-kappaB2-deficient mice have impaired T and B cell responses. We found, however, that in these mice there was severe infiltration of lymphocytes into multiple organs and increased activity of autoantibodies to peripheral tissue antigens in a manner similar to that of autoimmune regulator-deficient (Aire-deficient) mice. We further demonstrated that NF-kappaB2 was required for thymic Aire gene transcriptional regulation. The Nfkb2(-/-) thymus had distinct cortical and medullar structures, but reduced Aire and target gene expression of peripheral tissue antigens. Engraftment of Nfkb2(-/-) thymic stroma to nude mice recapitulated the autoimmune phenotype of the native Nfkb2(-/-) mice, confirming a key defect in central tolerance. Lymphotoxin beta receptor (LTbetaR) ligation-induced Aire gene expression was also largely abolished in the absence of NF-kappaB2. Thus NF-kappaB2 downstream of LTbetaR plays an important role in the regulation of central tolerance in an Aire-dependent manner.

Animals↗

Aire-deficient mice develop hematopoetic irregularities and marginal zone B-cell lymphoma.

Autoimmune polyendocrine syndrome type I (APS I) is an inherited recessive disorder with a progressive immunological destruction of many tissues including the adrenal cortex, the parathyroid glands, and the gonads. APS I is caused by mutations in the AIRE gene (autoimmune regulator), expressed in cells of the thymus and spleen, suggesting a role in central and peripheral tolerance. Aire(-/-) mice replicate the autoimmune features of APS I patients with the presence of multiple autoantibodies and lymphocytic infiltrates in various tissues, but young mice appear clinically healthy. We here report the investigation of 15- to 24-month-old Aire(-/-) mice. We did not observe any endocrinological abnormalities, nor did sera from these mice recognize known APS I autoantigens. Interestingly, however, there was a high frequency of marginal zone B-cell lymphoma in Aire(-/-) mice and liver infiltrates of B cells, suggesting chronic antigen exposure and exaggerated activation. Furthermore, increased numbers of monocytes in blood were identified as well as augmented numbers of metallophilic macrophages in the spleen. We propose that Aire, in addition to its function in the thymus, also has a peripheral regulatory role by controlling the development of antigen-presenting cells (APCs) and marginal zone B-cell activation.

Animals↗

Autoimmune polyendocrine syndrome type 1 in Norway: phenotypic variation, autoantibodies, and novel mutations in the autoimmune regulator gene.

CONTEXT: The autoimmune polyendocrine syndrome type I (APS I) is a rare disease that previously was difficult to diagnose. Autoantibody screening as well as mutational analysis of the disease gene autoimmune regulator (AIRE) are important diagnostic tools for this life-threatening syndrome. OBJECTIVE: The objective of the study was to identify all patients with APS I in Norway and correlate their clinical features with their autoantibody profiles and mutations in the AIRE gene. PATIENTS: We identified 36 Norwegian patients from 24 families with APS I (20 males, 16 females) during a nationwide survey for patients with Addison's disease and polyendocrine syndromes, seven of them only after their death. RESEARCH DESIGN AND METHODS: Clinical data were collected from questionnaires and patient records. AIRE mutations were determined by DNA sequencing. Most autoantibodies were measured in RIAs against recombinant autoantigens, but anti-type I interferon (IFN) antibodies were titrated in ELISA or antiviral interferon neutralization assays. RESULTS: The prevalence of APS I in Norway was estimated to be about 1:90,000. Several patients exhibited a milder phenotype with few APS I disease components and onset only in late adolescent or adulthood. The others showed about the same distribution of disease components as reported in Finnish patients. Eleven different mutations were identified in the AIRE gene, six of these were novel, i.e. c.22C>T (p.Arg8Cys), c.290T>C (p.Leu97Pro), c.402delC (p.Ser135GlnfsX12), c.879 + 1G>A (p.IVS7 + 1G>A), c.1249dupC (p.Leu417ProfsX7), and c.1336T>G (p.Cys446Gly). The 13-bp deletion in exon 8 (c.967-979del13) was the most prevalent mutation, present in 23 of 48 (48%) of the alleles. The presence of neutralizing autoantibodies against IFN-omega was the most specific marker of APS I, being found in all but one Norwegian patient. Some other common APS I-associated autoantibodies appeared de novo during long-term follow-up of younger patients. CONCLUSIONS: Norwegian patients with APS I clinically resemble those from Finland and other European countries, but some have milder phenotypes. In total, six new mutations were identified in the Norwegian APS I patients. Anti-type I IFN autoantibodies are easily detectable; their APS I specificity and persistently high titers render them reliable markers of APS I, even in prodromal or atypical cases. Both the clinical features and the AIRE mutations are more diverse in the Norwegian population than previously thought.

Addison Disease↗

Severe autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy in an adolescent girl with a novel AIRE mutation: response to immunosuppressive therapy.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder for which the gene (AIRE) has recently been identified on chromosome 21q22.3. We present the mutational analyses of a French-Canadian family with APECED, in which there are two affected siblings, as well as the response to cyclosporine A(CyA) therapy in the index patient, the eldest sibling. Haplotype analysis suggested compound heterozygozity at the AIRE locus. Direct sequencing of exon 8 revealed a previously described mutation, a 13-bp deletion (1085-1097) of maternal origin, found in the index patient, her affected sister, and her unaffected sister. A novel missense mutation characterized by a T-->G transversion at nucleotide position 398, resulting in a leu-->arg amino acid substitution (L93R), was found in exon 2. The mutation was present in the father, the brother, the index patient, and the affected sister. The presence of the mutation in the propositus was verified by cloning of PCR products from genomic DNA. The mutation destroys a PstI restriction enzyme site, as confirmed in the aforementioned patients. Screening of 50 French-Canadian controls with PstI digestion did not show destruction of the restriction-enzyme site. The index patient's phenotype was severe, manifested by classic features of the illness (adrenal insufficiency, hypoparathyroidism, candidiasis, and keratoconjunctivitis with alopecia universalis), as well as by severe exocrine pancreatic insufficiency, diabetes mellitus, hepatic inflammation, growth hormone (GH) deficiency due to lymphocytic hypophysitis, and primary ovarian failure. Oral CyA (5 mg/kg/day) was initiated at 13 yr of age. After 8 months of therapy, stimulated pancreatic lipase increased 24-fold with normalization of stool fat (from 31.5 g/day to 2.5 g/day, normal(N) < 5). There was complete resolution of her photophobia, and considerable hair regrowth was diffusely apparent. Minimal side effects were noted. Our experience supports the use of oral CyA for the treatment of severe APECED-associated exocrine pancreatic failure and keratoconjunctivitis.

Adolescent↗

Association analysis of the cytotoxic T lymphocyte antigen-4 (CTLA-4) and autoimmune regulator-1 (AIRE-1) genes in sporadic autoimmune Addison's disease.

Although autoimmune Addison's disease (AAD) may occur as a component of the monogenic autoimmune polyendocrinopathy type 1 syndrome (APS1), it is most commonly found as an isolated disorder or associated with the autoimmune polyendocrinopathy type 2 syndrome (APS2). It is likely that sporadic (non-APS1) AAD is inherited as a complex trait; however, apart from the major histocompatibility complex, the susceptibility genes remain unknown. We have examined polymorphisms at two non-major histocompatibility complex candidate susceptibility loci in sporadic (non-APS1) AAD: the cytotoxic T lymphocyte antigen-4 (CTLA-4) gene and the autoimmune regulator (AIRE-1) gene. DNA samples from AAD subjects (n = 90) and local controls (n = 144 for CTLA-4; n = 576 for AIRE-1) were analyzed for the CTLA-4A/G polymorphism in exon 1 of the CTLA-4 gene and for the common mutant AIRE-1 allele (964de113) in United Kingdom subjects with APS1, by using the restriction enzymes Bst7II and BsrBI, respectively. There was an association of the G allele at CTLA-4A/G in AAD subjects (P = 0.008 vs. controls), which was stronger in subjects with AAD as a component of APS2 than in subjects with isolated AAD. In contrast, the mutant AIRE-1 964del13 allele was carried in one each of the 576 (0.2%) control subjects and the 90 (1.1%) AAD subjects as a heterozygote (P = 0.254, not significant), suggesting that this common AIRE-1 gene abnormality does not have a major role in sporadic (non-APS1) AAD.

Abatacept↗

A heterozygous deletion of the autoimmune regulator (AIRE1) gene, autoimmune thyroid disease, and type 1 diabetes: no evidence for association.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autoimmune disease with endocrine components including type 1 diabetes, adrenal failure, and thyroid dysfunction, with major autoantibodies directed against adrenal, pancreas, and thyroid tissue. A 13-bp deletion in exon 8 of the autoimmune regulator (AIRE1) gene on chromosome 21q22.3 accounts for more than 70% of mutant alleles in United Kingdom subjects with APECED. To determine whether this polymorphism contributes to disease susceptibility in subjects with autoimmune disease in general, we screened 302 patients with Graves' disease, 154 patients with autoimmune hypothyroidism, 235 patients with type 1 diabetes, and 318 control subjects for the 13-bp deletion of the AIRE1 gene. The mutation was present in only 1 (0.33%) patient with Graves' disease, 1 patient with autoimmune hypothyroidism (0.6%), and 1 (0.315) of the control subjects. No patients with type 1 diabetes were found to carry the mutation. We conclude, therefore, that the 13-bp deletion of the AIRE1 gene is not a susceptibility locus for the more common autoimmune endocrinopathies in the United Kingdom.

Chromosomes, Human, Pair 21↗

AIRE mutations and human leukocyte antigen genotypes as determinants of the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy phenotype.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED, OMIM 240300) is a rare autoimmune disease caused by mutations in the autoimmune regulator (AIRE) gene on chromosome 21q22.3. This monogenic disease provides an interesting model for studies of other common and more complex autoimmune diseases. The most common components of APECED are chronic mucocutaneous candidiasis, hypoparathyroidism, and Addison's disease, but several other endocrine deficiencies and ectodermal dystrophies also occur and the phenotype varies widely. The AIRE genotype also varies; 42 different mutations have been reported so far. To understand the complexity of the phenotype, we studied the AIRE and human leukocyte antigen (HLA) class II genotypes in a series of patients with APECED. The only association between the phenotype and the AIRE genotype was the higher prevalence of candidiasis in the patients with the most common mutation, R257X, than in those with other mutations. Addison's disease was associated with HLA-DRB1*03 (P = 0.021), alopecia with HLA-DRB1*04- DQB1*0302 (P < 0.001), whereas type 1 diabetes correlated negatively with HLA-DRB1*15-DQB1*0602 (P = 0.036). The same HLA associations have previously been established for non-APECED patients. We conclude that mutation of AIRE per se has little influence on the APECED phenotype, whereas, in contrast to earlier reports, HLA class II is a significant determinant.

Adolescent↗