A common and recurrent 13-bp deletion in the autoimmune regulator gene in British kindreds with autoimmune polyendocrinopathy type 1

Autoimmune Addison disease: pathophysiology and genetic complexity

Autoimmune Addison disease is a rare autoimmune disorder with symptoms that typically develop over months or years. Following the development of serum autoantibodies to the key steroidogenic enzyme, 21-hydroxylase, patients have a period of compensated or preclinical disease, characterized by elevations in adrenocortocotropic hormone and renin, before overt, symptomatic adrenal failure develops. We propose that local failure of steroidogenesis, causing breakdown of tolerance to adrenal antigens, might be a key factor in disease progression. The etiology of autoimmune Addison disease has a strong genetic component in man, and several dog breeds are also susceptible. Allelic variants of genes encoding molecules of both the adaptive and innate immune systems have now been implicated, with a focus on the immunological synapse and downstream participants in T lymphocyte antigen-receptor signaling. With the exception of MHC alleles, which contribute to susceptibility in both human and canine Addison disease, no major or highly penetrant disease alleles have been found to date. Future research into autoimmune Addison disease, making use of genome-wide association studies and next-generation sequencing technology, will address the gaps in our understanding of the etiology of this disease.

Transcription factors in parathyroid development: lessons from hypoparathyroid disorders

Parathyroid developmental anomalies, which result in hypoparathyroidism, are common and may occur in one in 4,000 live births. Parathyroids, in man, develop from the endodermal cells of the third and fourth pharyngeal pouches, whereas, in the mouse they develop solely from the endoderm of the third pharyngeal pouches. In addition, neural crest cells that arise from the embryonic mid- and hindbrain also contribute to parathyroid gland development. The molecular signaling pathways that are involved in determining the differentiation of the pharyngeal pouch endoderm into parathyroid cells are being elucidated by studies of patients with hypoparathyroidism and appropriate mouse models. These studies have revealed important roles for a number of transcription factors, which include Tbx1, Gata3, Gcm2, Sox3, Aire1 and members of the homeobox (Hox) and paired box (Pax) families.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy: insights into genotype-phenotype correlation

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare autosomal recessive disease, caused by mutations of a single gene named autoimmune regulator gene (AIRE) which results in a failure of T cell tolerance within the thymus. Chronic mucocutaneous candidiasis, chronic hypoparathyroidism, and Addison's disease are the hallmarks of the syndrome. APECED is also characterized by several autoimmune endocrine and nonendocrine manifestations, and the phenotype is often complex. Moreover, even though APECED is a monogenic disease, its clinical picture is generally dominated by a wide heterogeneity both in the severity and in the number of components even among siblings with the same AIRE genotype. The variability of its clinical expression implies that diagnosis can be challenging, and a considerable delay often occurs between the appearance of symptoms and the diagnosis. Since a prompt diagnosis is essential to prevent severe complications, clinicians should be aware of all symptoms and signs of suspicion. The aim of this paper is to give an overview on the clinical presentation and diagnostic criteria of APECED and to focus on current knowledge on genotype-phenotype correlation.

Clinical heterogeneity and diagnostic delay of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive organ-specific autoimmune disorder that is characterized by a variable combination of (i) chronic mucocutaneous candidiasis, (ii) polyendocrinopathy and/or hepatitis and (iii) dystrophy of the dental enamel and nails. We analyzed the AIRE (autoimmune regulator) gene in subjects who presented any symptom that has been associated with APECED, including candidiasis and autoimmune endocrinopathy. We observed that 83.3% of patients presented at least two of the three typical manifestations of APECED, while the remaining 16.7% of patients showed other signs of the disease. Analysis of the genetic diagnosis of these subjects revealed that a considerable delay occurs in the majority of patients between the appearance of symptoms and the diagnosis. Overall, the mean diagnostic delay in our patients was 10.2 years. These results suggest that molecular analysis of AIRE should be performed in patients with relapsing mucocutaneous candidiasis for early identification of APECED.

The role of AIRE in human autoimmune disease

The autoimmune regulator (AIRE) gene encodes a transcription factor involved in the presentation of tissue-restricted antigens during T-cell development in the thymus. Mutations of this gene lead to type 1 autoimmune polyglandular syndrome (APS-1), also termed autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome, which is characterized by the clinical presentation of at least two of a triad of underlying disorders: Addison disease, hypoparathyroidism and chronic mucocutaneous candidiasis. This Review describes the process of positive and negative selection of developing T cells in the thymus and the role of AIRE as a regulator of peripheral antigen presentation. Furthermore, it addresses how mutations of this gene lead to the failure to eliminate autoreactive T cells, which can lead to clinical autoimmune syndromes.

Challenges in management of primary hypoparathyroidism associated with autoimmune polyglandular syndrome type 1

We report a case of autoimmune polyglandular syndrome type 1 (APS1) complicated by severe vascular insufficiency due to diffuse vascular calcification. APS1 is characterised clinically by multiple autoimmune conditions and development of at least two components of the triad of mucocutaneous candidiasis, hypoparathyroidism, and autoimmune adrenal insufficiency. We highlight the problems in current serum calcium monitoring methods and suggest that fluctuations in serum calcium concentrations due to difficulties treating hypoparathyroidism may have contributed to the vascular calcification seen in this case.

Novel sequence variation of AIRE and detection of interferon-omega antibodies in early infancy

OBJECTIVE

Autoimmune polyendocrine syndrome type I (APS I) is a rare primary immunodeficiency disorder characterized by chronic mucocutaneous candidiasis, multi-organ autoimmunity and ectodermal dysplasia. Autoantibodies to parathyroid and adrenal glands and type I interferons (IFN) are hallmarks of APS I, which results from mutations in the autoimmune regulator (AIRE) gene. We wished to study clinical, immunological and genetic features of APS I in Hungarian patients, and to correlate anti-IFN-omega serum concentration with APS I and other multi-organ autoimmune diseases.

DESIGN

Detailed analysis of patients with APS I and multi-organ autoimmune diseases.

PATIENTS

Seven patients with APS I and 11 patients with multi-organ autoimmune diseases were studied.

MEASUREMENTS

Mutational analysis was performed by bidirectional sequencing of AIRE. Antibodies against IFN-omega and endocrine organ-specific autoantigens were studied with radioimmunoassay. RFLP was performed by digestion of DNA with Hin6I restriction enzyme.

RESULTS

AIRE sequence analysis revealed homozygous c.769C>T mutations in three patients and compound heterozygous sequence variants (c.769C>T/c.44_66dup26bp; c.769C>T/c.965_977del13bp; c.769C>T/c.1344delC) in four patients with APS I. All the six live patients tested had markedly elevated IFN-omega antibodies, which were not found in heterozygous siblings or parents. One of the identified patients was negative for antibodies against IFN-omega at 6 weeks of age, but became positive at 7 months. At age 1, he is still without symptoms of the disease. In contrast to patients with APS I, no AIRE mutation or elevation of IFN-omega antibodies were detected in patients with multi-organ autoimmune diseases.

CONCLUSION

This is the first overview of patients diagnosed with APS I in Hungary. A novel c.1344delC mutation in AIRE was detected. Anti-IFN-omega antibodies seem to appear very early in life and are helpful to differentiate APS I from other multi-organ autoimmune diseases.

Oral mucous squamous cell carcinoma-an anticipated consequence of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED)

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disease caused by mutations in the AIRE gene. We report the case of a female patient with a 967-979del13 mutation in the AIRE gene. Her medical history included autoimmune hypoparathyroidism, Addison disease, and chronic mucocutaneous candidiasis. At the age of 40, she developed multiple white verrucous plaques on the oral mucosa. Histologically, the lesions appeared as moderately differentiated squamous cell carcinomas. The patient subsequently developed multiple local recurrences and therefore required repeated surgery. Notably, a higher incidence rate of oral and esophageal squamous cell carcinoma has been observed in this syndrome. However, the critical pathogenetic pathways implicated in squamous cell carcinoma development in APECED are far from being well understood.

Two novel AIRE mutations in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) among Indians

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare recessive disorder resulting from mutations in the autoimmune regulator (AIRE) gene. There is no information on AIRE mutations in Indians. In a cross-sectional study, nine patients (eight families), from four referral hospitals in India, were studied for AIRE mutations by direct sequencing. We screened for new mutations in 150 controls by allele-specific PCR. The patients had 1-7 known components of APECED. Three patients had unusual manifestations: presentation with type 1 diabetes; chronic sinusitis and otitis media; and facial dysmorphism. All patients carried homozygous, probably recessive, AIRE mutations. Two unrelated patients from a small in-bred community (Vanika Vaisya) in south India carried an unreported missense mutation, p.V80G, in the N-terminal caspase recruitment domain. Another unique mutation, p.C302X, resulting in a truncated protein with deletion of both zinc-finger domains, was detected in a patient from Gujarat. Neither mutation was detected in controls. Other mutations, previously described in Caucasians, were: 13 base pair deletion (p.C322fsX372) in 4 (38%), and Finn-major (p.R257X) and p.R139X (Sardinian) mutation in one subject each. In conclusion, in this first series of APECED in Indians, we detected AIRE mutations previously reported in Caucasians, as well as unique mutations. Of these, p.V80G is possibly an ancestral mutation in an in-bred community.

Novel and recurrent mutations in the AIRE gene of autoimmune polyendocrinopathy syndrome type 1 (APS1) patients

Autoimmune polyendocrinopathy syndrome type 1 (APS1) is characterized by the presence of at least two out of three clinical features, which include Addison's disease, hypoparathyroidism, and chronic mucocutaneous candidiasis. This disorder is caused by mutations in the AIRE (autoimmune regulator) gene. While several AIRE mutations have been described in APS1 patients of various ethnic origins, the genetic cause of APS1 in Arab patients requires further investigation. This study describes seven Arab families, in which 18 patients had APS1. In addition to the cardinal features of APS1, some patients exhibited alopecia, diabetes mellitus, nephrocalcinosis and other phenotypes associated with APS1. DNA sequencing of the AIRE gene of patients from this study identified four novel and one recurrent mutation. These mutations likely result in loss of AIRE function in the patients. In addition, it was noted that the non-pathogenic c.834C> G mutation (rs1800520, encoding for p.Ser278Arg) occurs with high incidence in the AIRE gene of Arab individuals. Furthermore, this investigation demonstrates inflammation of the hair follicles in APS1 patients with alopecia universalis. We conclude that Arab APS1 patients carry novel and recurrent mutations in the AIRE gene.

Autosomal dominant chronic mucocutaneous candidiasis and primary hypothyroidism complicated by oesophageal carcinoma

We describe three generations of a white family with autosomal dominant chronic mucocutaneous candidiasis (CMCC) and primary hypothyroidism, which was complicated by squamous cell carcinoma (SCC) of the oesophagus in the index case. We report this family to increase awareness of this rare autosomal dominant variant of CMCC endocrinopathy syndrome associated with primary hypothyroidism without evidence of autoimmune endocrinopathy, and to highlight the risk of developing oesophageal SCC at a young age as a fatal complication of CMCC.

Diagnosis and management of polyendocrinopathy syndromes

The autoimmune polyendocrinopathy syndromes are variable in presentation and can be challenging to diagnose and manage. Diagnosis of the type 1 autoimmune polyendocrinopathy syndrome can be difficult at an early age when often only one manifestation is present, and it may take years for others to appear. Increased awareness of polyendocrinopathy syndromes, combined with analysis of specific autoantibodies and molecular genetics, should help earlier diagnosis of these conditions and prevent serious complications. Further definition of susceptibility genes and autoantigens, as well as a better understanding of the pathogenesis, is required to improve the diagnosis and management of these patients.

Autoimmune polyendocrine syndrome type 1 (APS-1) as a model for understanding autoimmune polyendocrine syndrome type 2 (APS-2)

Autoimmune polyendocrine syndromes type 1 and 2 (APS-1 and APS-2) are diverse in regards to their component diseases and immunologic features of pathogenesis. Animal models and human studies highlight the importance of alleles of HLA (human leukocyte antigen)-like molecules determining tissue specific targeting that with the loss of tolerance leads to organ specific autoimmunity. Knowledge of the syndromes and component diseases allows clinicians to recognize and prevent illness prior to morbidity. With the current understanding of the syndromes, a paradigm for diagnosis, screening and treatment can be established. Once genetically susceptible individuals are identified screening for autoantibodies can be performed. Amongst autoantibody positive individuals, monitoring for physiologic decompensation, with a goal of treating prior to morbidity and in some cases mortality, follows. With continued basic and clinical research, therapies aimed at treating the underlying autoimmunity and disease prevention should become possible.

Monogenic autoimmune diseases: insights into self-tolerance

Autoimmune diseases affect a significant segment of the population and are typically thought to be multifactorial in etiology. Autoimmune diseases due to single gene defects are rare, but offer an invaluable window into understanding how defects in the immune system can lead to autoimmunity. In this review, we will focus on autoimmune polyendocrinopathy syndrome type 1 and recent advances in our understanding of this disease. We will also discuss two other monogenic autoimmune diseases: immunodysregulation, polyendocrinopathy, and enteropathy, X-linked and Autoimmune lymphoproliferative syndrome. Importantly, the knowledge and principles gained from studying these diseases have been applicable to more common autoimmune diseases and have opened the door to better diagnostic and therapeutic modalities.

Evaluation of the autoimmune regulator (AIRE) gene mutations in a cohort of Italian patients with autoimmune-polyendocrinopathy-candidiasis-ectodermal-dystrophy (APECED) and in their relatives

OBJECTIVE

Autoimmune-polyendocrinopathy-candidiasis-ectodermal-dystrophy (APECED) is a rare syndrome characterized by chronic candidiasis, chronic hypoparathyroidism and Addison's disease. APECED has been associated with mutations in autoimmune regulator (AIRE) gene. Our aim is to perform a genetic analysis of the AIRE gene in Italian APECED patients and in their relatives. Design AIRE mutations were determined by DNA sequencing in all subjects. Patients were tested for clinical autoimmune or non-autoimmune diseases, or for organ and non-organ specific autoantibodies.

PATIENTS

A total of 24 Italian patients with APECED (15 from the Venetian region, 2 from Southern-Tyrol, 4 from Apulia, 3 from Sicily), 25 relatives and 116 controls were studied.

RESULTS

Ten out of the 15 Venetian patients (66%) were homozygous for R257X or compound heterozygous with 1094-1106del13. One patient was homozygous for 1094-1106del13 and another for R139X. A novel mutation (1032-1033delGT) in combination with 1094-1106del13 was identified in one patient. No mutations were found in two cases. Two patients from Southern Tyrol were homozygous for R257X and for 1094-1106del13bp. All patients from Apulia were homozygous or heterozygous for W78R combined with Q358X. The patients from Sicily were homozygous for R203X or compound heterozygous with R257X. The analysis of the genotype-phenotype revealed that patients carrying 1094-1106del13 at the onset of Addison's disease were significantly older than those carrying other mutations. The genetic study of 25 relatives identified 20 heterozygous subjects. They suffered from various autoimmune and non-autoimmune diseases but no major disease of APECED was found.

CONCLUSION

These data demonstrate the great genetic heterogeneity for the AIRE mutations in Italian APECED patients, and that the heterozygosity for AIRE mutations do not produce APECED.

The proinflammatory cytokine TNF-alpha -308 AA genotype is associated with polyglandular autoimmunity

Data regarding polymorphisms of immunoregulatory genes in polyglandular autoimmunity (PGA) are lacking. We have analyzed whether the polymorphism of the proinflammatory cytokine gene TNF-alpha; -308 and mutations of the autoimmune regulator (AIRE) gene were associated with PGA in adults. Sixty-seven patients with PGA and 209 healthy controls were genotyped by multiplex minisequencing with capillary electrophoresis on an ABI PRISM-310 genetic analyzer. HLA DRB1 typing was performed using polymerase-chain-reaction-amplified DNA hybridized with sequence-specific-oligonucleotide probes (PCR-SSO). The TNF-alpha; -308*A allele occurred more frequently in patients (0.269) than in controls (0.163, P = 0.008, P(c) = 0.016). Also, TNF-alpha; -308*A carriers were more frequent in patients than controls (47.8% vs. 31.1%, OR = 1.89, 95%CI = 1.19-3.00). The frequency of the AA genotype was increased in PGA (P = 0.014, P(c) = 0.042). PGA patients with autoimmune thyroid disease and the TNF-alpha; -308 AA genotype showed the highest prevalence of thyroid autoantibodies (TPO, P = 0.04; Tg, P = 0.003). HLA-DRB1*03 and TNF-alpha; -308*A alleles were strongly associated in patients with PGA (87.5%, P(c) < 0.00001). The AIRE R257X and 13bpdel mutations were not observed in patients with PGA. The association of TNF-alpha; -308*A with PGA might be directly or indirectly due to the association with HLA-DRB1*03.

Resolving the conundrum of islet transplantation by linking metabolic dysregulation, inflammation, and immune regulation

Although type 1 diabetes cannot be prevented or reversed, replacement of insulin production by transplantation of the pancreas or pancreatic islets represents a definitive solution. At present, transplantation can restore euglycemia, but this restoration is short-lived, requires islets from multiple donors, and necessitates lifelong immunosuppression. An emerging paradigm in transplantation and autoimmunity indicates that systemic inflammation contributes to tissue injury while disrupting immune tolerance. We identify multiple barriers to successful islet transplantation, each of which either contributes to the inflammatory state or is augmented by it. To optimize islet transplantation for diabetes reversal, we suggest that targeting these interacting barriers and the accompanying inflammation may represent an improved approach to achieve successful clinical islet transplantation by enhancing islet survival, regeneration or neogenesis potential, and tolerance induction. Overall, we consider the proinflammatory effects of important technical, immunological, and metabolic barriers including: 1) islet isolation and transplantation, including selection of implantation site; 2) recurrent autoimmunity, alloimmune rejection, and unique features of the autoimmune-prone immune system; and 3) the deranged metabolism of the islet transplant recipient. Consideration of these themes reveals that each is interrelated to and exacerbated by the other and that this connection is mediated by a systemic inflammatory state. This inflammatory state may form the central barrier to successful islet transplantation. Overall, there remains substantial promise in islet transplantation with several avenues of ongoing promising research. This review focuses on interactions between the technical, immunological, and metabolic barriers that must be overcome to optimize the success of this important therapeutic approach.

Chromosome 21 abnormalities: a review and report of a case of Erondu-Cymet syndrome

The co-existence of rare clinical findings in a patient with a genetic abnormality has often led to the characterization of new syndromes. Although these genetic syndromes are generally rare, the pathophysiology of these disorders has broadened our understanding of common medical conditions. The variety of disorders that map to chromosome 21 provide insight into the effects of lifelong low pO2 and poor perfusion on various organs. In discovering the different disorders that map specifically to chromosome 21, we can characterized, treat and even prevent some medical conditions. We present the case of a man whose incidental finding of hypoxemia lead to the discovery of many unusual disorders that appear to be related to abnormalities in chromosome 21.

Genomic polymorphism at the interferon-induced helicase (IFIH1) locus contributes to Graves' disease susceptibility

CONTEXT

A recent large-scale analysis of nonsynonymous coding polymorphisms showed strong evidence that an alanine to threonine amino acid change at codon 946 of the interferon-induced helicase (IFIH1) gene (SNP ID rs1990760) was associated with type 1 diabetes. Previous investigations have also demonstrated that an intronic polymorphism (termed PD1.3; SNP ID rs11568821) in the programmed cell death (PDCD1) gene was associated with systemic lupus erythematosus and rheumatoid arthritis.

OBJECTIVE

We sought to replicate these genetic associations in Graves' disease and autoimmune Addison's disease patient cohorts.

PATIENTS AND METHODS

A total of 602 Graves' disease subjects, 214 Addison's disease subjects, and 446 healthy controls were genotyped for the IFIH1 and PDCD1 single-nucleotide polymorphisms using mass spectrometer analysis of primer extension products (Sequenom).

RESULTS

The alanine-carrying allele at the IFIH1 codon 946 polymorphism was present in 796 of 1204 (66%) Graves' disease patient alleles compared with 508 of 892 (57%) control subject alleles [odds ratio 1.47 (5-95% confidence interval, 1.23-1.76); P = 1.9 x 10(-5)]. In contrast, there was no association of alleles at this marker in autoimmune Addison's disease. Neither was there evidence for association in either patient cohort at the PD1.3 polymorphism.

CONCLUSIONS

We confirm a significant contribution of the Ala946Thr IFIH1 polymorphism to organ-specific autoimmune diseases, extending the range of conditions associated with this variant to include Graves' disease. This polymorphism may also contribute to several other autoimmune disorders.

Resolution of autoimmune polyglandular syndrome-associated keratopathy with keratolimbal stem cell transplantation: case report and historical literature review

PURPOSE

To describe the presentation and treatment of a case of autoimmune polyglandular syndrome type 1 (APS1)-associated keratopathy and to review the associated literature.

METHODS

A 23-year-old man with decreased vision secondary to APS1-associated keratopathy was treated with systemic immunosuppression and keratolimbal allograft (KLAL) stem cell transplantation.

RESULTS

The patient maintains excellent vision 27 months after KLAL and systemic immunosuppression.

CONCLUSIONS

An underlying etiology of APS1-associated keratopathy is stem cell deficiency, which can be treated effectively with KLAL and systemic immunosuppression.

The role of the IDDM2 locus in the susceptibility of UK APS1 subjects to type 1 diabetes mellitus

Autoimmune polyendocrinopathy syndrome type 1 (APS1) is characterized by autoimmune destruction of endocrine tissues and chronic mucocutaneous candidiasis. Type 1 diabetes (T1D) affects 12-25% of patients with APS1, and the prediction of whether this complication will affect an individual is not currently possible. However, alleles of a variable number tandem repeat (VNTR) 5' of the insulin gene are known to influence the development of T1D in the general, non-APS1 population. Therefore, we investigated the prevalence of these IDDM2 alleles in British Caucasian patients with APS1. The study employed genotyping of 33 patients with APS1 for the HphI polymorphism that is in tight linkage disequilibrium with the insulin gene VNTR alleles. Thirty-three patients with APS1 were studied, the mean age was 23.5 years and 24% have T1D. Six of eight (75%) APS1 patients with T1D were homozygous for the class I INS VNTR (susceptibility) allele, compared with eight of 25 (32%) of APS1 patients without T1D (P = 0.042). Our data suggest an association between the development of T1D and homozygosity for the T1D susceptibility class IINS VNTR allele in patients with APS1.

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.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) in the Irish population

OBJECTIVE

To determine the Irish prevalence of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), the AIRE mutations involved and clinical features of this population.

METHODS

All patients were identified through paediatricians and endocrinologists in Ireland. Patients were invited to attend a multidisciplinary clinic.

RESULTS

Thirty-one patients (2-56 years), 18 female, were identified from 19 families giving an Irish prevalence of 1:130,000. Twenty-six patients had hypoparathyroidism, 21 had adrenal insufficiency (AI) and 10 of 16 had ovarian failure. Three affected patients have died. Many with hypoparathyroidism were resistant to 1-alpha-vitamin D. Two needed daily PTH injections. Mineralocorticoid deficiency as the first manifestation of AI was common. Chronic intra-oral candidiasis affected 25 patients and three had leukoplakia. Two had keratoconjuntivitis. Of 22 with AIRE gene analysis, three different mutations were identified, one of which is novel.

CONCLUSION

APECED is rare in Ireland. We saw a significant amount of non-endocrine disease but no ectodermal dystrophy. AIRE gene analysis reassured many siblings and identified individuals with APECED prior to any symptoms.

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.

Oral and oesophageal squamous cell carcinoma--a complication or component of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED, APS-I)

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal recessive disease exceptionally common in Finland. It is associated with a limited T lymphocyte defect, an autoimmune response to various tissues, particularly endocrine glands. Most patients have chronic oral candidosis, which has been suggested to be carcinogenic. In Finland 92 patients have been diagnosed with APECED and 66 of them are alive. Our aim was to study the possible association of APECED with oral and oesophageal carcinoma. We evaluated the medical histories of all 92 patients for morbidity, causes of death, and known risk factors for oral cancer. We invited all current patients for a clinical examination of their oral mucosa. Six of the 92 had developed oral or oesophageal squamous cell carcinoma (SCC) by the mean age of 37 (29-44years) and four of them had died from it. The six represent 10% of the patients older than 25years. Five of the six patients had long-lasting oral candidosis. Four of the six had smoked regularly for 15years or more. One patient had been on immunosuppressive therapy for 6years following kidney transplantation when SCC in her mouth occurred. The partial T cell defect of APECED seems to favour the growth of Candida albicans and predispose to chronic mucositis and SCC. Aggressive control of oral candidosis and close follow-up of oral mucosa is a necessity in patients with APECED.

Fine mapping of a region on chromosome 21q21.11-q22.3 showing linkage to type 1 diabetes

BACKGROUND

Results of a Scandinavian genome scan in type 1 diabetes mellitus (T1D) have recently been reported. Among the novel, not previously reported chromosomal regions showing linkage to T1D was a region on chromosome 21.

OBJECTIVE

To fine map this region on chromosome 21.

METHODS AND RESULTS

The linked region was initially narrowed by linkage analysis typing microsatellite markers. Linkage was significantly increased, with a peak NPL score of 3.61 (p = 0.0002), suggesting the presence of one or several T1D linked genes in the region. The support interval for linkage of 6.3 Mb was then studied by linkage disequilibrium (LD) mapping with gene based single nucleotide polymorphisms (SNPs). Thirty two candidate genes were identified in this narrowed region, and LD mapping was carried out with SNPs in coding regions (cSNPs) of all these genes. However, none of the SNPs showed association to T1D in the complete material, whereas some evidence for association to T1D of variants of the TTC3, OLIG2, KCNE1, and CBR1 genes was observed in conditioned analyses. The disease related LD was further assessed by a haplotype based association study, in which several haplotypes showed distorted transmission to diabetic offspring, substantiating a possible T1D association of the region.

CONCLUSIONS

Although a single gene variant responsible for the observed linkage could not be identified, there was evidence for several combinations of markers, and for association of markers in conditioned analyses, supporting the existence of T1D susceptibility genes in the region.

Immunodeficiencies with Autoimmune Consequences

Far from being mutually exclusive, immunodeficiency and autoimmunity may occur simultaneously. During the last years, analysis of Autoimmune Polyendocrinopathy--Candidiasis--Ectodermal Dystrophy (APECED) and Immunodysregulation--Polyendocrinopathy--Enteropathy--X-linked (IPEX), two rare monogenic forms of immunodeficiency associated with autoimmunity, has led to the identification of Auto Immune Regulator (AIRE) and Forkhead Box P3 (FOXP3), essential transcriptional regulators, involved in central tolerance and peripheral immune homeostasis, respectively. Characterization of the molecular and cellular mechanisms involved in APECED, and recognition that AIRE expression is sustained by effective thymopoiesis, has recently allowed to define that the autoimmunity of Omenn syndrome, a combined immunodeficiency due to defects of V(D)J recombination, also results from defective expression of AIRE. The implications of identification of the basis of autoimmunity in these rare forms of immunodeficiency have important implications for a better understanding of more common autoimmune disorders, and for development of novel therapeutic approaches.

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.

The development of mouse APECED models provides new insight into the role of AIRE in immune regulation

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy is a rare recessive autoimmune disorder caused by a defect in a single gene called AIRE (autoimmune regulator). Characteristics of this disease include a variable combination of autoimmune endocrine tissue destruction, mucocutaneous candidiasis and ectodermal dystrophies. The development of Aire-knockout mice has provided an invaluable model for the study of this disease. The aim of this review is to briefly highlight the strides made in APECED research using these transgenic murine models, with a focus on known roles of Aire in autoimmunity. The findings thus far are compelling and prompt additional areas of study which are discussed.

Immunogenetics of Hashimoto's thyroiditis

Hashimoto's thyroiditis (HT) is an organ-specific T-cell mediated disease. It is a complex disease, with a strong genetic component. To date, significant progress has been made towards the identification and functional characterization of HT susceptibility genes. In this review, we will summarize the recent advances in our understanding of the genetic input to the pathogenesis of HT.

Immunoregulatory and susceptibility genes in thyroid and polyglandular autoimmunity

The etiology of autoimmune thyroid diseases (AITD) is based on genetic and nongenetic factors. Genome-wide screening and linkage analyses have identified several chromosomal regions that are linked to AITD. These are HT-1 (on chromosome 13q33) and HT-2 (chromosome 12q22) for Hashimoto's thyroiditis (HT), and GD-1 (chromosome 14q31), GD-2 (chromosome 20q11.2), and GD-3 (chromosome Xq21) for Graves' disease (GD). Several genes have been proposed as susceptibility or immunoregulatory genes. Most promising genes are those of the major histocompatibility complex (MHC) complex (chromosome 6), the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene (chromosome 2), the CD40 (chromosome 20), the thyroglobulin gene (chromosome 8), and the autoimmune regulator gene (chromosome 21). This review summarizes evidence for pathogenetic involvement of several of these genes in various forms of autoimmune thyropathies. Most genetic data refer to GD, whereas less data are available for HT and thyroid-associated ophthalmopathy. Scarce data refer to AITD within the autoimmune polyglandular syndromes I and II. The realization of family studies in large samples from different populations might provide further insight in the genetic contribution to AITD. Data are also needed on the interaction among susceptibility genes. Finally, additional functional studies are warranted to clarify the possible role of allelic variants in the underlying pathogenic mechanisms of AITD.

Genetic insights into disease mechanisms of autoimmunity

Educating the immune system to distinguish between self and non-self is critical to ensure that an immune response is mounted against foreign antigens and not against self. A breakdown in these mechanisms can lead to the onset of autoimmune disease. Clinical and molecular data suggest that shared immunogenetic mechanisms lead to the autoimmune process. The most studied genes and molecules are the human leukocyte antigen (HLA) region and the cytotoxic T-lymphocyte-associated 4 molecule (CTLA-4). Recently progress has been achieved in narrowing down the primary variants within both gene regions, but further work is needed to determine the function and extent of the aetiological variant(s) present. Recent exciting results also suggest a role for the newly discovered lymphoid-specific phosphatase (LYP) protein. As well as these general mechanisms, disease-specific mechanisms are beginning to be elucidated, for example the role of autoimmune regulatory element 1 (AIRE1) in autoimmune polyendocrinopathy-candidiasis ectodermal dystrophy (APECED). Taken together, these data suggest that both general and disease-specific mechanisms lead to the clinical outcome of autoimmune disease and that increased understanding of these mechanisms will improve our knowledge of how autoimmune disease occurs, eventually leading to the development of novel therapeutic agents.

Novel compound heterozygous AIRE mutations in a Japanese patient with APECED

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder defined by the presence of two of three conditions, namely, Addison's disease, hypoparathyroidism, and mucocutaneous candidiasis. APECED is caused by alteration in a single gene, named the autoimmune regulator (AIRE) gene. We report AIRE gene mutations in a Japanese female with APECED. The patient is a 22-year-old Japanese female who was diagnosed with Addison's disease, hypoparathyroidism, and mucocutaneous candidiasis at age 8 years. Sequence analysis of the AIRE gene revealed novel compound heterozygous mutations. One was 1471 delCinsTT in exon 11 (GenBank accession no. AB006682), which leads to a frameshift and premature truncation of a 502 amino acid protein. The other was a G-->A transition at IVS11+1. Her mother was heterozygous for 1471 delCinsTT and was normal homozygous for IVS11+1. We found novel compound heterozygous mutations in the AIRE gene of a Japanese female with APECED.

No significant association between mutations in exons 6 and 8 of the autoimmune regulator (AIRE) gene and inflammatory bowel disease

Various autoantibodies have been described in patients with inflammatory bowel disease. The autoimmune regulator (AIRE) functions as a transcription factor in cells responsible for the induction and maintenance of immunological tolerance. In contrast to classic autoimmune disorders, polymorphisms of the AIRE gene are not associated with inflammatory bowel disease, despite the presence of disease-specific autoantibodies.

Autoimmune polyglandular syndrome type 1 and the autoimmune regulator

The autoimmune polyglandular syndrome type I (APSI) is an auto-somal recessive disorder that is characterized by chronic mucocutaneous candidiasis, multiple autoimmune endocrinopathies, and ectodermal dystrophies. The gene that is responsible for APSI has been identified as autoimmune regulator (AIRE). More than 50 different mutations have been discovered in patients who have APSI and the defects include nonsense and missense mutations, small insertions and deletions that lead to frameshift, and splice site mutations. The 545-amino acid protein that is encoded by AIRE contains several structural motifs that are suggestive of a transcriptional regulator. We provide an overview of the clinical and genetic features ofAPSI as well as the structure and functions of the AIRE protein.

APECED-causing mutations in AIRE reveal the functional domains of the protein

A defective form of the AIRE protein causes autoimmune destruction of target organs by disturbing the immunological tolerance of patients with a rare monogenic disease, autoimmune polyendocrinopathy (APE)-candidiasis (C)-ectodermal dystrophy (ED), APECED. Recently, experiments on knockout mice revealed that AIRE controls autoimmunity by regulating the transcription of peripheral tissue-restricted antigens in thymic medullary epithelial cells. Thus, AIRE provides a unique model for molecular studies of organ-specific autoimmunity. In order to analyze the molecular and cellular consequences of 16 disease-causing mutations in vitro, we studied the subcellular localization, transactivation capacity, homomultimerization, and complex formation of several mutant AIRE polypeptides. Most of the mutations altered the nucleus-cytoplasm distribution of AIRE and disturbed its association with nuclear dots and cytoplasmic filaments. While the PHD zinc fingers were necessary for the transactivation capacity of AIRE, other regions of AIRE also modulated this function. Consequently, most of the mutations decreased transactivation. The HSR domain was responsible for the homomultimerization activity of AIRE; all the missense mutations of the HSR and the SAND domains decreased this activity, but those in other domains did not. The AIRE protein was present in soluble high-molecular-weight complexes. Mutations in the HSR domain and deletion of PHD zinc fingers disturbed the formation of these complexes. In conclusion, we propose an in vitro model in which AIRE transactivates transcription through heteromeric molecular interactions that are regulated by homomultimerization and conditional localization of AIRE in the nucleus or in the cytoplasm.

Erythropoietin-deficient anemia associated with autoimmune polyglandular syndrome type I

Autoimmune polyglandular syndrome type I (APS1), a relatively common disorder in some populations, is frequently associated with adrenal insufficiency, hypoparathyroidism, and other endocrine and skin abnormalities. We describe an 18-year-old male with APS1, as documented by genotyping, who presented with hypoparathyroidism and a normocytic, hypoproliferative, isolated anemia. An extensive hematological work-up revealed a low serum erythropoietin, without any other hematological abnormalities. His renal function was normal, and he did not have many of the laboratory or clinical findings associated with an anemia of chronic disease. His anemia was responsive to superphysiologic doses of erythropoietin. We thus suggest that erythropoietin deficiency may be one of the endocrine abnormalities associated with APS1, and clinicians should be cognizant of the association of treatable anemia in patients with APS1.

A comparative study of mRNA and protein expression of the autoimmune regulator gene (Aire) in embryonic and adult murine tissues

Autoimmune polyendocrine syndrome type 1 (APS1) is a rare autosomal recessive human disorder caused by mutations in the autoimmune regulator gene (AIRE) and characterized by multiple autoimmune diseases. As reports of the tissue expression pattern of the murine Aire gene are discordant, a comprehensive survey of Aire expression was undertaken in adult and embryonic tissues at the mRNA and protein levels using real-time RT-PCR, in situ hybridization, and immunohistochemistry. In the adult, the highest Aire mRNA expression was in the thymus. All the other tissues investigated expressed Aire mRNA at low levels, but it was barely detectable in the adrenal gland. Aire protein expression was observed in the thymus, spleen, and lymph nodes. A common pattern was observed in other tissues, with staining in epithelial cells. An exception to this was the gut, where staining was seen in the mucin spaces. In embryonic tissue, Aire mRNA and protein expression was detected from E14.5 in the thymus. In the fetal liver, unlike the adult, staining was observed at E14.5 and decreased towards term. Thus, Aire is expressed in immunologically relevant tissues and in a restricted number of extra-immunological tissues in the adult. Furthermore, the presence of Aire protein is reported in extra-thymic tissues of the embryo.

Rapid onset childhood cataracts leading to the diagnosis of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

PURPOSE

To report a case of bilateral cataracts in a child that led to diagnosis of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy.

DESIGN

Observational case report.

METHODS

A 12-year-old boy was being investigated for weakness, lethargy, short stature, and blurred vision. He developed bilateral, dense cataracts over a 2-week period. He was found to be hypocalcemic and diagnosed with hypoparathyroidism and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy.

RESULTS

Because of hypoparathyroidism, adrenocortical failure, and insulin-dependent diabetes, it was 9 months before the patient's metabolic imbalance was brought under sufficient control to allow cataract surgery.

CONCLUSIONS

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy should be considered with diagnoses of hypocalcemic cataract.

The genetics of autoimmune endocrine disease

The common autoimmune endocrinopathies result from an interaction between environmental factors and genetic predisposition. Several chromosomal gene regions have been shown to contribute to more than one disease, supporting the clinical observation that the autoimmune endocrine diseases cluster within individuals and families. Genetic studies have implicated the major histocompatability complex (MHC)-human leucocyte antigen (HLA) genes on chromosome 6p21, although this chromosomal region does not explain all of the genetic contribution to the various disorders. Non-MHC-HLA genes, including disease-specific loci, are beginning to be identified and the publication of the draft sequence of the human genome will undoubtedly expediate future discoveries. Combined with the establishment of large cohorts of subjects with disease and the development of technology capable of performing high-throughput genotyping, genetic studies are likely to impact on the future treatment and prevention of the common autoimmune endocrine diseases.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome: time to review diagnostic criteria?

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal-recessive syndrome defined by two of the following conditions: chronic mucocutaneous candidiasis, hypoparathyroidism, or Addison's disease. Other autoimmune conditions may be associated, such as hypothyroidism, hypogonadism, insulin-dependent diabetes mellitus, chronic active hepatitis, pernicious anemia, vitiligo, alopecia, biliary cirrhosis, and ectodermal dysplasia. APECED is caused by mutations in the autoimmune regulator gene, mapping to 21q22.3. We report on three patients whose clinical and molecular features challenge the currently used diagnostic criteria for APECED. AR presented at 15 yr of age with a history of recurrent infections and mucocutaneous candidiasis. He is now 21 yr old, and no other signs or symptoms of APECED have appeared to date. DR presented at 7 yr of age with hypocalcemia and a prolonged Q-T interval on the electrocardiogram. He also had minor facial dysmorphisms and mild mental retardation. Serum calcium levels were low, PTH levels were undetectable, and hypoparathyroidism was therefore diagnosed. All other biochemical, immunological, and endocrinological tests were normal. DR is now 8 yr old with no other signs or symptoms of APECED. ST presented at 14 yr of age for alopecia aerata and pitted nail dystrophy and goiter. Thyroid function was normal in the presence of thyroid-specific antibodies. No other signs or symptoms of APECED have appeared to date. Genetic analysis revealed a typical mutation (R257X) on a single allele in both AP and DR; in ST, heterozygosity for a novel mutation (V484M) involving one of the zinc fingers of the plant homeodomain of the protein was found. The finding of a typical APECED mutation in two patients presenting with one isolated major clinical APECED feature and of a novel mutation in a patient presenting with atypical features of APECED onset suggests that the time might have come for updating the diagnostic criteria of this syndrome.