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The expression of self-antigen in the thymus is believed to be responsible for the deletion of autoreactive T lymphocytes, a critical process in the maintenance of unresponsiveness to self. The Autoimmune regulator (Aire) gene, which is defective in the disorder autoimmune polyglandular syndrome type 1, has been shown to promote the thymic expression of self-antigens. A clear link, however, between specific thymic self-antigens and a single autoimmune phenotype in this model has been lacking. We show that autoimmune eye disease in aire-deficient mice develops as a result of loss of thymic expression of a single eye antigen, interphotoreceptor retinoid-binding protein (IRBP). In addition, lack of IRBP expression solely in the thymus, even in the presence of aire expression, is sufficient to trigger spontaneous eye-specific autoimmunity. These results suggest that failure of thymic expression of selective single self-antigens can be sufficient to cause organ-specific autoimmune disease, even in otherwise self-tolerant individuals.

Homozygous loss-of-function mutations in AIRE cause autoimmune polyglandular syndrome type 1 (APS 1), which manifests in a classic triad of hypoparathyroidism, adrenal insufficiency, and candidiasis. Interestingly, a kindred with a specific G228W AIRE variant presented with an autosomal dominant autoimmune phenotype distinct from APS 1. We utilized a novel G228W-knockin mouse model to show that this variant acted in a dominant-negative manner to cause a unique autoimmunity syndrome. In addition, the expression of a large number of Aire-regulated thymic antigens was partially inhibited in these animals, demonstrating the importance of quantitative changes in thymic antigen expression in determining organ-specific autoimmunity. Furthermore, the dominant-negative effect of the G228W variant was exerted through recruitment of WT Aire away from active sites of transcription in the nucleus of medullary thymic epithelial cells in vivo. Together, these results may demonstrate a mechanism by which autoimmune predisposition to phenotypes distinct from APS 1 can be mediated in a dominant-negative fashion by Aire.

Mutations in the Autoimmune regulator (Aire) gene result in a clinical phenomenon known as Autoimmune Polyglandular Syndrome Type I (APS1), which classically manifests as a triad of adrenal insufficiency, hypoparathyroidism, and chronic mucocutaneous infections. In addition to this triad, a number of other autoimmune diseases have been observed in APS1 patients including Sjögren's syndrome, vitiligo, alopecia, uveitis, and others. Aire-deficient mice, the animal model for APS1, have highlighted the role of the thymus in the disease process and demonstrated a failure in central tolerance in aire-deficient mice. However, autoantibodies have been observed against multiple organs in both mice and humans, making it unclear what the specific role of B and T cells are in the pathogenesis of disease. Utilizing the aire-deficient mouse as a preclinical model for APS1, we have investigated the relative contribution of specific lymphocyte populations, with the goal of identifying the cell populations which may be targeted for rational therapeutic design. Here we show that T cells are indispensable to the breakdown of self-tolerance, in contrast to B cells which play a more limited role in autoimmunity. Th1 polarized CD4+ T cells, in particular, are major contributors to the autoimmune response. With this knowledge, we go on to utilize therapies targeted at T cells to investigate their ability to modulate disease in vivo. Depletion of CD4+ T cells using a neutralizing antibody ameliorated the disease process. Thus, therapies targeted specifically at the CD4+ T cell subset may help control autoimmune disease in patients with APS1.

In autoimmune polyglandular syndromes (APS), several organ-specific autoimmune diseases are clustered. Although APS type I is caused by loss of central tolerance, the etiology of APS type II (APS-II) is currently unknown. However, in several murine models, depletion of CD4+ CD25+ regulatory T cells (Tregs) causes a syndrome resembling human APS-II with multiple endocrinopathies. Therefore, we hypothesized that loss of active suppression in the periphery could be a hallmark of this syndrome. Tregs from peripheral blood of APS-II, control patients with single autoimmune endocrinopathies, and normal healthy donors showed no differences in quantity (except for patients with isolated autoimmune diseases), in functionally important surface markers, or in apoptosis induced by growth factor withdrawal. Strikingly, APS-II Tregs were defective in their suppressive capacity. The defect was persistent and not due to responder cell resistance. These data provide novel insights into the pathogenesis of APS-II and possibly human autoimmunity in general.

Autoimmune Polyglandular Syndrome (APS) Type 1 is a rare hereditary disorder that damages organs in the body. This disease entity is the result of a mutation in the AIRE gene. It is characterized by three classic clinical features - hypoparathyroidism, Addison's disease, and chronic mucocutaneous candidiasis. For a patient to be diagnosed as having APS Type 1 syndrome at least two of these features needs to be present. The third entity may develop as the disease progresses. We report a case of a 35-year-old female patient with a history of seizure from the age of 11 years, who was managed with anticonvulsant drugs. With worsening of the seizure episodes, patient was diagnosed to have hypoparathyroidism together with the manifestations of oral candidiasis, nails dystrophy, enamel hypoplasia, and hypogonadism. A diagnosis of APS-1 was considered. The facility for genetic analysis of the AIRE gene mutation was not accessible, as the test costs were prohibitive and not affordable for the patient. Patient management was directed to treating individual disease components. However, cerebral and dental changes were irreversible.

Acquired hypoparathyroidism (AH) has been considered to result from an autoimmune process but the self-antigens have not been identified. We studied 25 patients with AH, of which 17 had type I autoimmune polyglandular syndrome and 8 had AH associated with autoimmune hypothyroidism. Five of 25 (20%) AH sera reacted to a membrane-associated antigen of 120-140 kD in human parathyroid gland extracts using immunoblot analysis. This is the exact size of the calcium sensing receptor (Ca-SR). The AH sera were then tested by immunoblot using a membrane fraction of HEK-293 cells transfected with Ca-SR cDNA. Eight of 25 (32%) AH sera reacted to a 120-140-kD protein, which closely matched that recognized by the anti-Ca-SR IgG raised in rabbits. The Ca-SR cDNA was translated in vitro into two parts in order to identify the antigenic epitopes. By using this technique, 14 of 25 (56%) AH sera were positive to the extracellular domain of the Ca-SR, whereas none of the AH patients sera reacted to the intracellular domain. The reactivity of the positive sera was completely removed after pre-absorption with the Ca-SR containing membranes. Sera from 50 patients with various other autoimmune diseases as well as 22 normal controls were also tested, and none of them was positive. In conclusion, the Ca-SR has been identified as an autoantigen in AH.

Type I polyglandular autoimmune syndrome is characterized by the triad of hypoparathyroidism, Addison's disease and chronic mucocutaneous candidiasis. Chronic active hepatitis has been associated with this syndrome but its incidence and severity have not been well documented. We describe a sibship of two patients with type I polyglandular autoimmune syndrome who presented with autoimmune chronic active hepatitis. The first patient presented to us with advanced disease and died despite an emergent liver transplant, while the second patient responded to steroids. Autoimmune chronic active hepatitis, a major cause of mortality in this syndrome, can present without symptoms or physical signs of liver disease. We suggest periodic screening of liver enzymes in subjects with this syndrome.

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High titer antibodies to type 1 interferons have been recently reported as being highly specific for patients with autoimmune polyglandular syndrome type 1 (APS1) in Finnish and Norwegian patients with mutations in the AIRE gene. Those studies employed a complex neutralization assay to define the type 1 interferon autoantibodies. Here we have established a competitive europium time resolved fluorescence assay for IFN-a autoantibodies and measured sera from subjects with APS1, first degree relatives of APS1 patients, patients with Addison’s disease or Type 1 diabetes. The europium-based immunoassay utilizes plate bound human IFN-a incubated with sera with or without competition with fluid phase IFN-a, followed by anti-IgG biotinylated antibody and detection with streptavidin-europium. The index of IFN-a Ab was calculated as (CPS (Counts per second) without competition-CPS with competition)/(CPS positive standard sera without competition-CPS positive standard sera with competition). Results are reported for raw CPS and indices and are compared across the different subjects.

Results

For normal controls (n=100) CPS without competition were 31,237±17,328 CPS while after subtracting the competition value, the results were −6,563±10,303 CPS. The initial APS1 patient (used to create the index as 1.0) gave 394,063 CPS without competition and a delta of 363,662±31,587 CPS with competition. Scatchard plot analysis of this patient sample revealed a high avidity for IFN-a (Kd of 0.5 nM). The CPS, delta, and index for 6/7 APS1 patients was strongly positive and 3 standard deviations or more above that of the normal controls. Using a cut–off of 2 standard deviations above normal controls, relatives of APS1 patients were negative for type I interferon autoantibodies as were 71 patients with Addison’s disease (non-APS1) and 141 Type 1 diabetes patients. This simple high throughput competitive europium time resolved fluorescence assay had a sensitivity of =86% or greater and a specificity of > 99.5%.

Background

The autoimmune regulator (AIRE) gene influences thymic self-tolerance induction. In autoimmune polyendocrinopathy syndrome type 1 (APS1; OMIM 240300), recessive AIRE mutations lead to autoimmunity targetting endocrine and other epithelial tissues, although chronic candidiasis usually appears first. Autoimmunity and chronic candidiasis can associate with thymomas as well. Patients with these tumours frequently also have high titre immunoglobulin G autoantibodies neutralising type I interferon (IFN)–α and IFN-ω, which are secreted signalling proteins of the cytokine superfamily involved in both innate and adaptive immunity.

Methods and Findings

We tested for serum autoantibodies to type I IFNs and other immunoregulatory cytokines using specific binding and neutralisation assays. Unexpectedly, in 60/60 Finnish and 16/16 Norwegian APS1 patients with both AIRE alleles mutated, we found high titre neutralising immunoglobulin G autoantibodies to most IFN-α subtypes and especially IFN-ω (60% homologous to IFN-α)—mostly in the earliest samples. We found lower titres against IFN-β (30% homologous to IFN-α) in 23% of patients; two-thirds of these (from Finland only) also had low titres against the distantly related “type III IFN” (IFN-λ1; alias interleukin-29). However, autoantibodies to the unrelated type II IFN, IFN-γ, and other immunoregulatory cytokines, such as interleukin-10 and interleukin-12, were much rarer and did not neutralise.

Neutralising titres against type I IFNs averaged even higher in patients with APS1 than in patients with thymomas. Anti–type I IFN autoantibodies preceded overt candidiasis (and several of the autoimmune disorders) in the informative patients, and persisted for decades thereafter. They were undetectable in unaffected heterozygous relatives of APS1 probands (except for low titres against IFN-λ1), in APS2 patients, and in isolated cases of the endocrine diseases most typical of APS1, so they appear to be APS1-specific.

Looking for potentially autoimmunising cell types, we found numerous IFN-α+ antigen-presenting cells—plus strong evidence of local IFN secretion—in the normal thymic medulla (where AIRE expression is strongest), and also in normal germinal centres, where it could perpetuate these autoantibody responses once initiated. IFN-α2 and IFN-α8 transcripts were also more abundant in antigen-presenting cells cultured from an APS1 patient's blood than from age-matched healthy controls.

Conclusions

These apparently spontaneous autoantibody responses to IFNs, particularly IFN-α and IFN-ω, segregate like a recessive trait; their high “penetrance” is especially remarkable for such a variable condition. Their apparent restriction to APS1 patients implies practical value in the clinic, e.g., in diagnosing unusual or prodromal AIRE-mutant patients with only single components of APS1, and possibly in prognosis if they prove to predict its onset. These autoantibody responses also raise numerous questions, e.g., about the rarity of other infections in APS1. Moreover, there must also be clues to autoimmunising mechanisms/cell types in the hierarchy of preferences for IFN-ω, IFN-α8, IFN-α2, and IFN-β and IFN-λ1.

Almost all of nearly 100 APS1 patients studied made large amounts of auto-antibodies that blocked the function of IFN-α and IFN-ω. The antibodies appeared early during development of the disease and may play a role in its etiology.

Editors' Summary

Background.

The human body is under constant attack by viruses, bacteria, fungi, and parasites, but the immune system usually prevents these pathogens from causing disease. To be effective, the immune system has to respond rapidly to foreign antigens (bits of protein specific to pathogens) while ignoring self-antigens. If tolerance to self-antigens breaks down, autoimmunity develops, often causing disease. There are many common autoimmune diseases—type I diabetes and multiple sclerosis, for example—but because these involve defects in many genes as well as environmental factors, the details of how autoimmunity develops remain unclear. Autoimmune polyendocrinopathy syndrome type 1 (APS1), however, is caused by defects in a single gene. Patients with this rare disease characteristically have defects (or mutations) in both copies of a gene called AIRE (for autoimmune regulator). In normal people, the protein product of this gene helps to establish tolerance to a subset of self-antigens. People carrying AIRE mutations make an autoimmune response against some of their own tissues, typically the endocrine (hormone-producing) tissues that control body metabolism. A major component of this autoimmune response are “autoantibodies” (antibodies are immune molecules that normally recognize and attack foreign substances, whereas autoantibodies are directed against the body's own molecules).

Why Was This Study Done?

For a diagnosis of APS1, a patient must have at least two of the following symptoms: recurrent, localized yeast infections (usually the first symptom of the disease to appear in early childhood), hypoparathyroidism (failure of the gland that controls calcium levels in the body), and Addison disease (failure of the steroid-producing adrenal glands, which help the body respond to stress). The researchers who did this study had previously noticed that these yeast infections and autoimmunity (usually against muscle) can also occur in patients with tumors of the thymus (thymomas). The thymus is the organ that generates immune cells called T cells. Generation of the T cell repertoire in the thymus involves selection of those T cells that recognize only foreign substances. T cells that can react against self-antigens are eliminated, and the AIRE gene is thought to be involved in this “education process.” Like those with APS1, patients with thymomas make autoantibodies not only against target organs (especially muscle in their case), but also against interferon alpha (IFN-α) and interferon omega (IFN-ω), two secreted immune regulators. The researchers wanted to know if patients with APS1 also make autoantibodies against interferons, because this could provide insights into how autoimmunity develops in APS1 and other autoimmune diseases.

What Did the Researchers Do and Find?

The researchers tested blood from nearly 100 APS1 patients for antibodies to IFN-α, IFN-ω, and other immunoregulatory cytokines. They found that almost all patients made large amounts of antibodies that blocked the function of IFN-α and IFN-ω; some also made lower amounts of antibodies against two related interferons, but none made blocking antibodies against unrelated interferons or other immune regulators. For many patients, serum samples were available at different times during their disease, which allowed the researchers to show that the antibodies appeared early in disease development, before the onset of yeast infections or damage to endocrine tissues, and their production continued for decades as the patient aged. Furthermore, only patients with APS1 made these antibodies—they were absent in patients with Addison disease alone, for example.

What Do These Findings Mean?

The discovery that autoantibodies to IFN-α and IFN-ω are made persistently in patients with APS1 suggests ways in which autoimmunity develops in these patients. These can now be investigated further both in patients and in animal models of the disease. The discovery also has practical implications. Measurement of these autoantibodies might help some APS1 patients by allowing earlier diagnosis—and prompter treatment—than in current practice. The levels of these autoantibodies might also help to predict the time course of APS1 in individual patients, although more studies will be needed to check this out. Finally, if future studies show that interferon autoantibodies are responsible for the patients' susceptibility to yeast infections (which seems plausible), treatment with IFN-γ, an interferon to which APS1 patients do not make autoantibodies, might provide an alternative way to deal with this problem.

Additional Information.

Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030289.

• MedlinePlus pages on autoimmune diseases

• Online Mendelian Inheritance in Man page on APS1

• Links to patient information on APS1 from the Stanford Health Library

• Wikipedia page on autoendocrine polyendocrinopathy (note: Wikipedia is a free online encyclopedia that anyone can edit)

• Information on autoimmunity from the American Autoimmune Related Diseases Association

Autoimmune disease affects a significant proportion of the population. The etiology of most autoimmune diseases is largely unknown, but it is thought to be multifactorial with both environmental and genetic influences. Rare monogenic autoimmune diseases, however, offer an invaluable window into potential disease mechanisms. In this review, we will discuss the autoimmune polyglandular syndrome (APS1), the immunedysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX), and autoimmune lymphoproliferative syndrome (ALPS). Significantly, the information gained from the study of these diseases has provided new insights into more common autoimmune disease and have yielded new diagnostics and therapeutic opportunities.

When immune dysfunction affects two or more endocrine glands and other non-endocrine immune disorders are present, the polyglandular autoimmune (PGA) syndromes should be considered. The PGA syndromes are classified as two main types: PGA type I and PGA type II. We are reporting this case in which a patient had primary adrenal insufficiency, autoimmune hypothyroidism and insulin dependent diabetes mellitus and was diagnosed as "Schmidt's syndrome" (PGA type II). This syndrome is a very rare autoimmune disorder and difficult to diagnose because the symptoms of this syndrome depends on the gland which gets involved first. Our patient was treated and improved with corticosteroid, thyroxine and insulin therapy.

The parathyroid glands are an infrequent target for autoimmunity; the exception being in the autoimmune polyglandular syndrome type 1, where autoimmune hypoparathyroidism is the rule. Antibodies that are directed against the parathyroid cell-surface calcium-sensing receptor (CaSR) have recently been recognised to be present in the serum of patients with autoimmune hypoparathyroidism. In some individuals, these anti-CaSR antibodies have also been shown to produce functional activation of the receptor, suggesting a direct pathogenic role in hypocalcemia. Additionally, a few hypercalcemic patients with autoimmune hyperparathyroidism owing to anti-CaSR antibodies that inhibit receptor activation have now been identified. Other novel parathyroid autoantigens are starting to be elucidated. These findings suggest that new approaches to treatment, such as CaSR antagonists or agonists (calcilytics/calcimimetics) may be worthwhile.

The polyglandular autoimmune syndrome (PGAS) is characterized by the association of two or more endocrine disorders that are mediated by autoimmune mechanisms and usually lead to a hypofunctional state. In this review we classify the various types of PGAS and discuss their clinical features and the pathophysiologic autoimmune mechanisms that are thought to play an important role. Circulating organ- and cell-specific autoantibodies are frequently detected in patients with the syndrome and may be a marker of future organ failure. PGAS should be considered in patients with one or more of the disorders constituting the syndrome; this should facilitate early diagnosis and perhaps even prevention of other components of the disease. Early recognition and replacement therapy can be life-saving, particularly when there is adrenal or thyroid insufficiency.

Autoimmune polyglandular syndromes (APSs) include a cluster of autoimmune and nonautoimmune conditions which have been classified into subtypes. APSs type 1 is characterized by at least two of the following: chronic mucocutaneous candidiasis, chronic hypoparathyroidism, and autoimmune Addison's disease (AD). We report the chronological history of a female patient who presented with features most consistent with APS type 1, along with growth hormone deficiency and juvenile rheumatoid arthritis (JRA). In terms of her autoimmune diagnoses, she first presented with JRA at three years of age, then hypocalcemia and hypoparathyroidism at five years of age, type 1 diabetes (DM 1) at age eleven years, adrenal insufficiency at age fourteen years, recurrent mucocutaneous candidiasis as a teenager, growth hormone deficiency at age fourteen years leading to significant short stature, primary amenorrhoea, and hypogonadism, and finally alopecia at age twenty-six years. In addition to this, she has suffered other nonautoimmune medical problems including a Tetralogy of Fallot with a surgical repair at age six years. On review of the medical literature, we found no other previously reported case with this unique combination of medical problems.

Autoimmune polyglandular syndrome, type 1 (APS-1) is a rare syndrome. Here we present a case report of a 24-year-old female patient who complained of progressive weakness. While autoimmune hepatitis was diagnosed, no improvement of biochemical parameters was obtained after immunosuppressive treatment. Hypoparathyroidism and adrenocortical failure were identified. Her health status clearly improved once proper control of the calcium-phosphate metabolism was obtained and after the administration of substitution hydrocortisone doses, leading to full normalization of biochemical liver tests. The reported case illustrates a rare form of APS-1 failure, in which the diagnosed autoimmune hepatitis was only the first symptom.

AIMS—To examine the age of onset of insulin dependent diabetes mellitus (IDDM) in children with Down's syndrome compared with non-trisomic individuals, and to assess whether differences might be related to disomic homozygosity at the autoimmune polyglandular disease type 1 (APECED) gene locus.
METHODS—Children with Down's syndrome and IDDM were identified through the Down's syndrome association newsletter and from paediatricians. DNA was extracted from mouthbrush preparations provided by the parents and patients using standard techniques. Mapping techniques were then used to identify areas of reduction to homozygosity, including a marker that overlaps the locus for APECED. The frequency of disomic homozygosity for all markers (n = 18) was compared with a control group of 99 patients with Down's syndrome and their parents. The families also answered a questionnaire concerning diabetes and related autoimmune conditions in the family. Details were compared with the British Paediatric Surveillance Group 1988diabetes study.
RESULTS—Children with Down's syndrome and IDDM were diagnosed significantly earlier than the general population (6.7 v 8.0 years) with a far higher proportion diagnosed in the first 2 years of life (22% v 7%). There was no evidence of increased disomic homozygosity in the region of the APECED locus in Down's syndrome patients with IDDM compared with simple Down's syndrome.
CONCLUSIONS—The natural history of IDDM in Down's syndrome is different from that of the general population. Although children with Down's syndrome have features similar to cases of APECED, disomic homozygosity in this region does not explain the predilection for autoimmune disease.



Background

Polymorphisms within the insulin gene can influence insulin expression in the pancreas and especially in the thymus, where self-antigens are processed, shaping the T cell repertoire into selftolerance, a process that protects from β-cell autoimmunity.

Methods

We investigated the role of the -2221Msp(C/T) and -23HphI(A/T) polymorphisms within the insulin gene in patients with a monoglandular autoimmune endocrine disease [patients with isolated type 1 diabetes (T1D, n = 317), Addison's disease (AD, n = 107) or Hashimoto's thyroiditis (HT, n = 61)], those with a polyglandular autoimmune syndrome type II (combination of T1D and/or AD with HT or GD, n = 62) as well as in healthy controls (HC, n = 275).

Results

T1D patients carried significantly more often the homozygous genotype "CC" -2221Msp(C/T) and "AA" -23HphI(A/T) polymorphisms than the HC (78.5% vs. 66.2%, p = 0.0027 and 75.4% vs. 52.4%, p = 3.7 × 10-8, respectively).

The distribution of insulin gene polymorphisms did not show significant differences between patients with AD, HT, or APS-II and HC.

Conclusion

We demonstrate that the allele "C" of the -2221Msp(C/T) and "A" -23HphI(A/T) insulin gene polymorphisms confer susceptibility to T1D but not to isolated AD, HT or as a part of the APS-II.

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.

We describe a young woman with primary adrenal insufficiency, hypoparathyroidism (autoimmune polyglandular syndrome type 1), Graves disease, vitiligo, and alopecia universalis. Five years after the diagnosis, she presented with recurrent ophthalmological and neurological disorders as features of Vogt-Koyanagi-Harada syndrome. A marked therapeutic response was noted on systemic high-dose corticosteroid treatment. To the best of our knowledge, such a spectre of autoimmune diseases has not been reported previously.

A female patient demonstrating a previously not reported constellation of polyglandular autoimmune syndrome type III (including autoimmune thyroiditis, Graves' ophthalmopathy, insulin-dependent diabetes mellitus and vitiligo), coeliac disease and sarcoidosis is described. This may be a random association but might also indicate a common immunological and/or genetic disturbance.

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We experienced the first case with autoimmune polyglandular syndrome type 3 (anti-thyroid peroxidase antibody-positive hypothyroidism and anti-glutamic acid decarboxylase antibody-positive diabetes) complicated by mineralocorticoid-responsive hyponatremia of the elderly. This case is also a rare slowly progressive insulin-dependent diabetes mellitus (SPIDDM) case, for which the patient has been treated for many years with sulfonylurea or glinide. Our observation also demonstrated that glucose metabolism in autoimmune diabetes such as SPIDDM is influenced by appetite, thyroid function and glucocorticoid effect.

Previously, we have demonstrated the presence of anti-calcium-sensing receptor (CaSR) antibodies in patients with autoimmune polyglandular syndrome type 1 (APS1), a disease that is characterized in part by hypoparathyroidism involving hypocalcemia, hyperphosphatemia, and low serum levels of parathyroid hormone. The aim of this study was to define the binding domains on the CaSR of anti-CaSR antibodies found in APS1 patients and in one patient suspected of having autoimmune hypocalciuric hypercalcemia (AHH). A phage-display library of CaSR peptides was constructed and used in biopanning experiments with patient sera. Selectively enriched IgG-binding peptides were identified by DNA sequencing, and subsequently, immunoreactivity to these peptides was confirmed in ELISA. Anti-CaSR antibody binding sites were mapped to amino acid residues 41–69, 114–126, and 171–195 at the N-terminal of the extracellular domain of the receptor. The major autoepitope was localized in the 41–69 amino acid sequence of the CaSR with antibody reactivity demonstrated in 12 of 12 (100%) APS1 patients with anti-CaSR antibodies and in 1 AHH patient with anti-CaSR antibodies. Minor epitopes were located in the 114–126 and 171–195 amino acid domains, with antibody reactivity shown in 5 of 12 (42%) and 4 of 12 (33%) APS1 patients, respectively. The results indicate that epitopes for anti-CaSR antibodies in the AHH patient and in the APS1 patients who were studied are localized in the N-terminal of the extracellular domain of the receptor. The present work has demonstrated the successful use of phage-display technology in the discovery of CaSR-specific epitopes targeted by human anti-CaSR antibodies. © 2010 American Society for Bone and Mineral Research.

Glucocorticoid-deficient hypoadrenocorticism (GDH) with immune-mediated-neutropenia (IMN) and -thrombocytopenia (IMT) were diagnosed in a 3-year-old Labrador retriever dog. Glucocorticoid-deficient hypoadrenocorticism is rare and diagnostically challenging as clinical signs and laboratory abnormalities are often nonspecific. Immune-mediated cytopenias and other autoimmune disorders, as part of an autoimmune polyglandular syndrome have been reported with hypoadrenocorticism in humans. This is the first reported case of hypoadrenocorticism and bicytopenia in a dog.

Polyglandular autoimmune syndrome (PAS) has been well characterised and the accepted criteria for diagnosis are the presence of at least two of the three major components: hypoparathyroidism (HPT), candidiasis, and adrenal insufficiency (AI). HPT may, however, be the only manifestation of the syndrome. Iranian Jews, having a high rate of consanguinity, appear to be a community in which PAS type I is frequent. We report on 19 families of patients with HPT from the Iranian Jewish community assuming that they are in fact affected with PAS type I. In the 19 families, 23 patients were affected, including 11 males and 12 females. All the patients but one had HPT (96%), and most were diagnosed by the age of 20 years (91%). AI was diagnosed in five of our patients; in all cases but one it appeared after HPT. Mild oral candidiasis was present in four patients and six of the patients (three males and three females) had hypogonadism. Other features of the syndrome found in some of our patients were pernicious anaemia, hypothyroidism, and alopecia. The disease is autosomal recessive and the calculated prevalence among the Iranian Jews is 1:6500 to 1:9000. The disease is also found with a very high incidence among Finns. A comparison of the symptoms between the two groups showed clinical differences including the relative rarity of candidiasis and absence of keratopathy among the Iranian Jews.

Background

Until recently, anti-SSA/Ro antibodies were not considered pathogenic for severe heart disease in adults. Prolongation of the mean QTc interval in electrocardiograms of adult patients with anti-SSA/Ro-positive connective tissue disease has been reported and could contribute to complex arrhythmias in such patients. Furthermore, complete heart block may also be related to these autoantibodies.

Case presentation

We describe the occurrence of fatal complete heart block in a euthyroid adult patient with undifferentiated connective tissue disease and polyglandular autoimmune syndrome type 2 associated with cardiovascular autonomic dysfunction who had normal QTc interval. The patient's serum contained anti-SSA/Ro.

Conclusion

This case might indicate that, although the adult heart conduction system may be relatively resistant to the development of anti-Ro-associated complete heart block, cardiac arrest may develop and even be fatal.