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

Cutaneous Manifestations in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy (APECED): A Comprehensive Review

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), or polyglandular autoimmune syndrome type 1 (PAS-1/APS-1), is a rare autosomal recessive disorder linked to mutations in the autoimmune regulator (AIRE) gene. This review provides a detailed analysis of cutaneous manifestations in APECED, focusing on chronic mucocutaneous candidiasis (CMC), alopecia areata (AA), and vitiligo. The classic triad of hypoparathyroidism, adrenal insufficiency, and CMC serves as a diagnostic cornerstone. However, the varied clinical spectrum of APECED, particularly its cutaneous presentations, poses a diagnostic challenge. CMC, often an early sign, varies in prevalence across populations, including Finnish (100%), Irish (100%), Saudi Arabian (80%), Italian (60-74.7%), North American (51-86%), and Croatian (57.1%) populations. Similarly, AA prevalence varies in different populations. Vitiligo also exhibits variable prevalence across regions. The review synthesizes the current knowledge arising from a narrative analysis of 14 significant human studies published in English up to October 2023. Moreover, this paper underscores the importance of early detection and monitoring, emphasizing cutaneous manifestations as key diagnostic indicators. Ongoing research and clinical vigilance are crucial for unraveling the complexities of this rare autoimmune syndrome and enhancing patient care.

A large single-center cohort of bare lymphocyte syndrome: Immunological and genetic features in Turkey

Major histocompatibility complex class II (MHC-II) deficiency or bare lymphocyte syndrome (BLS) is a rare, early-onset, autosomal recessive, and life-threatening inborn error of immunity. We aimed to assess the demographic, clinical, laboratory, follow-up, and treatment characteristics of patients with MHC-II deficiency, together with their survival. We retrospectively investigated 21 patients with MHC-II deficiency. Female/male ratio was 1.63. The median age at diagnosis was 16.3 months (5 months-9.7 years). Nineteen patients (90.5%) had parental consanguinity. Pulmonary diseases (pneumonia, chronic lung disease) (81%), diarrhoea (47.6%), and candidiasis (28.6%) were common. Four (19%) had autoimmunity, two developed septic arthritis, and three (14%) developed bronchiectasis in the follow-up. Three patients (14%) had CMV viraemia, one with bilateral CMV retinitis. Eight (38.1%) had lymphocytopenia, and four (19%) had neutropenia. Serum IgM, IgA, and IgG levels were low in 18 (85.7%), 15 (71.4%), and 11 (52.4%) patients, respectively. CD4+ lymphocytopenia, a reversed CD4+/CD8+ ratio, and absent/low HLA-DR expressions were detected in 93.3%, 86.7%, and 100% of the patients, respectively. Haematopoietic stem cell transplantation (HSCT) was performed on nine patients, and four died of septicaemia and ARDS after HSCT. The present median age of patients survived is 14 years (1-31 years). Genetic analysis was performed in 10 patients. RFX5 homozygous gene defect was found in three patients (P1, P4 and P8), and RFXANK (P2 and P14) and RFXAP (P18 and P19) heterozygous gene defects were found in each two patients, respectively. This large cohort showed that BLS patients have severe combined immunodeficiency (SCID)-like clinical findings. Flow cytometric MHC-II expression study is crucial for the diagnosis, differential diagnosis with SCID, early haematopoietic stem cell transplantation (HSCT), and post-HSCT follow-up. Genetic studies are required first for matched family donor evaluation before HSCT and then for genetic counselling.

APECED and the place of AIRE in the puzzle of the immune network associated with autoimmunity

In the last 20 years, discoveries about the autoimmune regulator (AIRE) protein and its critical role in immune tolerance have provided fundamental insights into understanding the molecular basis of autoimmunity. This review provides a comprehensive overview of the effect of AIRE on immunological tolerance and the characteristics of autoimmune diseases in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy (APECED), which is caused by biallelic AIRE mutations. A better understanding of the immunological mechanisms of AIRE deficiency may enlighten immune tolerance mechanisms and new diagnostic and treatment strategies for autoimmune diseases. Considering that not all clinical features of APECED are present in a given follow-up period, the diagnosis is not easy in a patient at the first visit. Longer follow-up and a multidisciplinary approach are essential for diagnosis. It is challenging to prevent endocrine and other organ damage compared with other diseases associated with multiple autoimmunities, such as FOXP3, LRBA, and CTLA4 deficiencies. Unfortunately, no curative therapy like haematopoietic stem cell transplantation or specific immunomodulation is present that is successful in the treatment.

Autoimmunity in Primary Immunodeficiencies (PID)

Primary immunodeficiency (PID) may impact any component of the immune system. The number of PID and immune dysregulation disorders is growing steadily with advancing genetic detection methods. These expansive recognition methods have changed the way we characterize PID. While PID were once characterized by their susceptibility to infection, the increase in genetic analysis has elucidated the intertwined relationship between PID and non-infectious manifestations including autoimmunity. The defects permitting opportunistic infections to take hold may also lead the way to the development of autoimmune disease. In some cases, it is the non-infectious complications that may be the presenting sign of PID autoimmune diseases, such as autoimmune cytopenia, enteropathy, endocrinopathies, and arthritis among others, have been reported in PID. While autoimmunity may occur with any PID, this review will look at certain immunodeficiencies most often associated with autoimmunity, as well as their diagnosis and management strategies.

Clinical Characteristics in the Longitudinal Follow-Up of APECED Syndrome in Southern Croatia—Case Series

Background: Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare monogenetic autosomal recessive disorder caused by a mutation in the autoimmune regulator (AIRE) gene characterized by complex phenotypic characteristics discovered over years of follow-up. Methods: 7 patients were recruited in this case series in a period of the last 37 years from Southern Croatia. All patients were screened for AIRE R257X mutations. Results: This study group had a mean current age of 25.3 years (age range from 5.4 to 40.2 years), while the mean age at the onset of the disease was 6.5 years (age range from 0.7 to 9.2 years) and with a mean follow-up period of 17.8 years. The overall prevalence of APECED syndrome is estimated to be 1 in 75,000. The most common initial manifestation of the disease was onychodystrophy, while the first major component of APECED syndrome was chronic mucocutaneous candidiasis. Conclusions: APECED is a ‘‘multi-faced’’ disease based on the very unpredictable and inconsistent onset of major components. Furthermore, based on our results, we suggest that onychodystrophy could be included as a warning sign of APECED syndrome.

The Impacts of Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dysplasia (APECED) on the Oral Health of Children and Young People: A Review and Case Report

Aim:

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare, highly variable disease with significant oral health impacts. The aim of the study is to examine the existing evidence base surrounding the oral health impacts of APECED and consider the wider clinical significance of the condition relevant to the provision of pediatric dental care.

Materials and Methods:

The evidence surrounding APECED and the oral health impacts obtained from a review of multiple databases was qualitatively summarized in the form of a literature review. A case study was used to illustrate the relevance of literature in caring patients with APECED.

Results:

The literature describes a broad range of impacts from APECED, although it is characterized by chronic candidal infection, autoimmune hypoparathyroidism, and Addison’s disease. Oral manifestations of APECED appear frequently and can present early. Developmental defects of the teeth affect a large proportion of patients with APECED and together with candidiasis, characterize the key oral manifestations of the disease. An enhanced preventive and minimally invasive approach to oral health care is recommended for these patients in light of the complexities of their medical condition.

Conclusion:

Patients with APECED require careful multidisciplinary care to ensure that the optimal oral health outcomes are achieved.

Co-Occurrence of Chronic Mucocutaneous Candidiasis with Woolly Hair

Chronic mucocutaneous candidiasis is an immunodeficiency state, inherited or acquired, characterized by recurrent and/or persistent candidiasis of skin, nails, and mucous membranes. Woolly hair is a congenital structural anomaly of scalp hair, characterized by light-colored, short, extremely kinky, and thin hair due to premature termination of anagen phase of hair cycle. Both conditions are known to present in syndromic and non-syndromic forms. We report the co-occurrence of both these conditions in a 10-year-old female child. The diagnosis was confirmed with clinical, trichoscopic, microbiologic, histopathologic, and laboratory evaluation, though mutational analysis could not be done due to resource constraints. The occurrence of both these diseases in the same individual has not been previously reported to the best of our knowledge. It could be a result of an association with ectodermal dysplasia.

Genetic syndromes with diabetes: A systematic review

Previous reviews and clinical guidelines have identified 10-20 genetic syndromes associated with diabetes, but no systematic review has been conducted to date. We provide the first comprehensive catalog for syndromes with diabetes mellitus. We conducted a systematic review of MEDLINE, Embase, CENTRAL, PubMed, OMIM, and Orphanet databases for case reports, case series, and observational studies published between 1946 and January 15, 2020, that described diabetes mellitus in adults and children with monogenic or chromosomal syndromes. Our literature search identified 7,122 studies, of which 160 fulfilled inclusion criteria. Our analysis of these studies found 69 distinct diabetes syndromes. Thirty (43.5%) syndromes included diabetes mellitus as a cardinal clinical feature, and 56 (81.2%) were fully genetically elucidated. Sixty-three syndromes (91.3%) were described more than once in independent case reports, of which 59 (93.7%) demonstrated clinical heterogeneity. Syndromes associated with diabetes mellitus are more numerous and diverse than previously anticipated. While knowledge of the syndromes is limited by their low prevalence, future reviews will be needed as more cases are identified. The genetic etiologies of these syndromes are well elucidated and provide potential avenues for future gene identification efforts, aid in diagnosis and management, gene therapy research, and developing personalized medicine treatments.

Case Report: Severe Hypocalcemic Episodes Due to Autoimmune Enteropathy

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic disorder, associated with endocrine deficiencies and non-endocrine involvement. Gastrointestinal (GI) manifestations appear in approximately 25% of patients and are the presenting symptom in about 10% of them. Limited awareness among pediatricians of autoimmune enteropathy (AIE) caused by destruction of the gut endocrine cells in APECED patients delays diagnosis and appropriate therapy. We describe an 18-year-old female presenting at the age of 6.10 years with hypoparathyroidism, oral candidiasis and vitiligo. The clinical diagnosis of APECED was confirmed by sequencing the autoimmune regulator-encoding (AIRE) gene. Several characteristics of the disease-Hashimoto's thyroiditis, Addison's disease, diabetes mellitus type 1 and primary ovarian insufficiency-developed over the years. She had recurrent episodes of severe intractable hypocalcemia. Extensive GI investigations for possible malabsorption, including laboratory analyses, imaging and endoscopy with biopsies were unremarkable. Revision of the biopsies and chromogranin A (CgA) immunostaining demonstrated complete loss of enteroendocrine cells in the duodenum and small intestine, confirming the diagnosis of AIE. Management of hypocalcemia was challenging. Only intravenous calcitriol maintained calcium in the normal range. Between hypocalcemic episodes, the proband maintained normal calcium levels, suggesting a fluctuating disease course. Repeated intestinal biopsy revealed positive intestinal CgA immunostaining. The attribution of severe hypocalcemic episodes to AIE emphasizes the need for increased awareness of this unique presentation of APECED. The fluctuating disease course and repeated intestinal biopsy showing positive CgA immunostaining support a reversible effect of GI involvement. CgA immunostaining is indicated in patients with APECED for whom all other investigations have failed to reveal an explanation for the malabsorption.

Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy in Two Siblings: Same Mutations but Very Different Phenotypes

Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED), caused by mutations in the AIRE gene, is mainly characterized by the triad of hypoparathyroidism, primary adrenocortical insufficiency and chronic mucocutaneous candidiasis, but can include many other manifestations, with no currently clear genotype–phenotype correlation. We present the clinical features of two siblings, a male and a female, with the same mutations in the AIRE gene associated with two very different phenotypes. Interestingly, the brother recently experienced COVID-19 infection with pneumonia, complicated by hypertension, hypokalemia and hypercalcemia. Although APECED is a monogenic disease, its expressiveness can be extremely different. In addition to the genetic basis, epigenetic and environmental factors might influence the phenotypic expression, although their exact role remains to be elucidated.

Autoimmune Polyglandular Syndrome Type 1: a case report

BACKGROUND

Mutations of the autoimmune regulator gene (AIRE), located on chromosome 21q22.3, are recognized as the cause of a rare monogenic organ-specific autoimmune disorder called autoimmune polyglandular syndrome type 1 (APS-1). Three major components of this syndrome include chronic mucocutaneous candidiasis (CMC), hypoparathyroidism, and adrenocortical failure.

CASE PRESENTATION

We report a 19-year-old girl, who was born in an Iranian Muslim family with a clinical diagnosis of APS-1. To identify the causative mutation, a direct sequencing of the entire AIRE gene sequence was performed by Sanger sequencing method. Three distinct variants were discovered, including c.1095 + 2 T > A, c.1197 T > C (rs1800521) and c.1578 T > C (rs1133779), in intron 9, exons 10 and 14 of the AIRE gene, respectively.

CONCLUSIONS

To the best of our knowledge, this is the first report of an Iranian Muslim APS-1 patient with combination of these variations. In addition, the effect of c.1095 + 2 T > A mutation on AIRE mRNA expression was reported for the first time. This study expands the diversity of variants that could cause APS-1. More genetic studies are required to determine the exact frequency of these variants and their diagnostic significance.

Monogenic polyautoimmunity in primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) consist of a large group of genetic disorders that affect distinct components of the immune system. PID patients are susceptible to infection and non-infectious complications, particularly autoimmunity. A specific group of monogenic PIDs are due to mutations in genes that are critical for the regulation of immunological tolerance and immune responses. This group of monogenic PIDs is at high risk of developing polyautoimmunity (i.e., the presence of more than one autoimmune disease in a single patient) because of their impaired immunity. In this review, we discuss the mechanisms of autoimmunity in PIDs and the characteristics of polyautoimmunity in the following PIDs: IPEX; monogenic IPEX-like syndrome; LRBA deficiency; CTLA4 deficiency; APECED; ALPS; and PKCδ deficiency.

Is multiple-site colonization with Candida spp. related to inadequate response to individualized fluconazole maintenance therapy in women with recurrent Candida vulvovaginitis?

OBJECTIVE

Although most women on fluconazole maintenance therapy for recurrent vulvovaginal candidosis experience a substantial improvement in quality of life, some do not respond to therapy. Is candidal colonization of extragenital sites related to suboptimal response to maintenance therapy?

PATIENTS AND METHODS

Women included in a multicenter follow-up study (ReCiDiF) were evaluated for clinical signs and presence of yeasts in nose, mouth, anus, perineum, and urine. Candida was diagnosed by positive microscopy, confirmed by positive culture or polymerase chain reaction. After treatment, women were divided into groups according to their response to a fluconazole maintenance regimen (optimal, suboptimal, and nonresponders).

RESULTS

The most frequent extravaginal Candida spp. were detected in urine (79.5%), perineum (78.6%), and anus (56.4%). Carriers of Candida in the mouth were more likely to have it in the anus (OR 3.2; 95% CI 1.4-7.7). Colonization in anus (OR 3.3; 95% CI 1.3-8.1) or in multiple extravaginal sites (OR 3.0; CI95% 1.2-7.4) was related to nonresponse to therapy. Candidal carriage in the anus did not increase anal and perianal symptoms.

CONCLUSION

Women with anal carriage and multiple-site candidal colonization are less likely to respond to individualized decreasing dose fluconazole therapy.

The Mechanisms of T Cell Selection in the Thymus

T cells undergo positive and negative selection in the thymic cortex and medulla, respectively. A promiscuous expression of a wide array of self-antigens in the thymus is essential for the negative selection of self-reactive T cells and the establishment of central tolerance. Aire was originally thought to be the exclusive factor regulating the expression of tissue-restricted antigens, but Fezf2 recently emerged as a critical transcription factor in this regulatory activity. Fezf2 is selectively expressed in thymic medullary epithelial cells, regulates a large number of tissue-restricted antigens and suppresses the onset of autoimmune responses. Here, we discuss novel findings on the transcriptional mechanisms of tissue restricted-antigen expression in the medullary thymic epithelial cells and its effects on T cell selection.

Morbid Sequences Suggest Molecular Mimicry between Microbial Peptides and Self-Antigens: A Possibility of Inciting Autoimmunity

Understanding etiology of autoimmune diseases has been a great challenge for designing drugs and vaccines. The pathophysiology of many autoimmune diseases may be attributed to molecular mimicry provoked by microbes. Molecular mimicry hypothesizes that a sequence homology between foreign and self-peptides leads to cross-activation of autoreactive T cells. Different microbial proteins are implicated in various autoimmune diseases, including multiple sclerosis, human type 1 diabetes, primary biliary cirrhosis and rheumatoid arthritis. It may be imperative to identify the microbial epitopes that initiate the activation of autoreactive T cells. Consequently, in the present study, we employed immunoinformatics tools to delineate homologous antigenic regions between microbes and human proteins at not only the sequence level but at the structural level too. Interestingly, many cross-reactive MHC class II binding epitopes were detected from an array of microbes. Further, these peptides possess a potential to skew immune response toward Th1-like patterns. The present study divulges many microbial target proteins, their putative MHC-binding epitopes, and predicted structures to establish the fact that both sequence and structure are two important aspects for understanding the relationship between molecular mimicry and autoimmune diseases. Such findings may enable us in designing potential immunotherapies to tolerize autoreactive T cells.

Pathogenic and Protective Autoantibodies in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy (APECED)

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare disorder caused by mutations in the autoimmune regulator (AIRE) gene, leading to defects in T cell selection. The disease manifestations include both autoimmune tissue destruction and immunodeficiency, with specific susceptibility to chronic mucocutaneous candidiasis. Studies have demonstrated a wide repertoire of high affinity tissue- and cytokine-specific antibodies in patients with APECED. Here, we review the antigenic targets and function of these disease-causing and disease-ameliorating antibodies.

Identification of autoimmune polyendocrine syndrome type 1 in patients with isolated hypoparathyroidism

OBJECTIVE

The prevalence of autoimmune polyendocrine syndrome type 1 (APS1) among isolated hypoparathyroidism (HP) or primary adrenal insufficiency (PAI) is not well established. We studied the frequency of APS1 in patients with HP or PAI by measuring interferon-α (IFN-α) antibody levels, a highly sensitive and specific marker for APS1.

DESIGN, PATIENTS AND MEASUREMENTS

In a single-centre cross-sectional study, 37 Indian patients with isolated HP and 40 patients with PAI were tested for IFN-α antibody using an indirect ELISA. In patients with elevated IFN-α antibody, the autoimmune regulator (AIRE) gene was bidirectionally sequenced.

RESULTS

Three (8·1%) patients with isolated HP had elevated IFN-α antibody levels (range: 367-17382 units; positive titre >56 units). Homozygous or compound heterozygous AIRE mutations were detected in all three patients, including a novel mutation (p.T68P). All three APS1 patients had atypical features. The first patient, diagnosed at 7 years of age, died suddenly 5 months later. The second patient had late-onset HP (at the age of 34 years) and a solitary episode of transient mucocutaneous candidiasis 5 years later. The final patient developed HP at the age of 14 years and premature ovarian insufficiency 14 years later. Interleukin-22 antibodies, as well as most other organ-specific antibodies, were absent in the 3 APS1 patients. All patients with PAI were negative for IFN-α antibody.

CONCLUSION

Eight percentage of patients with isolated HP had elevated IFN-α antibody levels and AIRE mutation-positive APS1. All APS1 patients had atypical clinical features. Testing for IFN-α antibody should be considered in patients with idiopathic HP.

Type 1 Diabetes in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy Syndrome (APECED): A "Rare" Manifestation in a "Rare" Disease

Type 1 autoimmune polyglandular syndrome (APS1) is a rare autosomal recessive disease, caused by mutations in the autoimmune regulator gene (AIRE); the encoded Aire protein plays an important role in the establishment of the immunological tolerance acting as a transcriptional regulator of the expression of organ-specific antigens within the thymus in perinatal age. While a high prevalence for this rare syndrome is reported in Finland and Scandinavia (Norway), autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) cohorts of patients are also detected in continental Italy and Sardinia, among Iranian Jews, as well as in other countries. The syndrome is diagnosed when patients present at least two out of the three fundamental disorders including chronic mucocutaneous candidiasis, hypoparathyroidism, and Addison's disease. Among the associated conditions insulin-dependent diabetes mellitus (Type 1 diabetes) has been rarely reported in different series of patients and occurring more frequently in Finnish APECED patients. In this review, we analyze the incidence of Type 1 diabetes as a clinical manifestation of APECED in different populations highlighting the peculiar genetic and immunological features of the disease when occurring in the context of this syndrome.

Autoimmunity in primary T-cell immunodeficiencies

Primary immunodeficiency diseases (PID) are a genetically heterogeneous group of more than 270 disorders that affect distinct components of both humoral and cellular arms of the immune system. Primary T cell immunodeficiencies affect subjects at the early age of life. In most cases, T-cell PIDs become apparent as combined T- and B-cell deficiencies. Patients with T-cell PID are prone to life-threatening infections. On the other hand, non-infectious complications such as lymphoproliferative diseases, cancers and autoimmunity seem to be associated with the primary T-cell immunodeficiencies. Autoimmune disorders of all kinds (organ specific or systemic ones) could be subjected to this class of PIDs; however, the most frequent autoimmune disorders are immune thrombocytopenic purpura (ITP) and autoimmune hemolytic anemia (AIHA). In this review, we discuss the proposed mechanisms of autoimmunity and review the literature reported on autoimmune disorder in each type of primary T-cell immunodeficiencies.

Novel Findings into AIRE Genetics and Functioning: Clinical Implications

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), formerly known as autoimmune polyendocrine syndrome type 1, is a paradigm of a monogenic autoimmune disease caused by mutations of a gene, named autoimmune regulator (AIRE). AIRE acts as a transcription regulator that promotes immunological central tolerance by inducing the ectopic thymic expression of many tissue-specific antigens. Although the syndrome is a monogenic disease, it is characterized by a wide variability of the clinical expression with no significant correlation between genotype and phenotype. Indeed, many aspects regarding the exact role of AIRE and APECED pathogenesis still remain unraveled. In the last decades, several studies in APECED and in its mouse experimental counterpart have revealed new insights on how immune system learns self-tolerance. Moreover, novel interesting findings have extended our understanding of AIRE's function and regulation thus improving our knowledge on the pathogenesis of APECED. In this review, we will summarize recent novelties on molecular mechanisms underlying the development of APECED and their clinical implications.

Unbalanced Immune System: Immunodeficiencies and Autoimmunity

Increased risk of developing autoimmune manifestations has been identified in different primary immunodeficiencies (PIDs). In such conditions, autoimmunity and immune deficiency represent intertwined phenomena that reflect inadequate immune function. Autoimmunity in PIDs may be caused by different mechanisms, including defects of tolerance to self-antigens and persistent stimulation as a result of the inability to eradicate antigens. This general immune dysregulation leads to compensatory and exaggerated chronic inflammatory responses that lead to tissue damage and autoimmunity. Each PID may be characterized by distinct, peculiar autoimmune manifestations. Moreover, different pathogenetic mechanisms may underlie autoimmunity in PID. In this review, the main autoimmune manifestations observed in different PID, including humoral immunodeficiencies, combined immunodeficiencies, and syndromes with immunodeficiencies, are summarized. When possible, the pathogenetic mechanism underlying autoimmunity in a specific PID has been explained.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

The Thymic Orchestration Involving Aire, miRNAs, and Cell-Cell Interactions during the Induction of Central Tolerance

Developing thymocytes interact sequentially with two distinct structures within the thymus: the cortex and medulla. Surviving single-positive and double-positive thymocytes from the cortex migrate into the medulla, where they interact with medullary thymic epithelial cells (mTECs). These cells ectopically express a vast set of peripheral tissue antigens (PTAs), a property termed promiscuous gene expression that is associated with the presentation of PTAs by mTECs to thymocytes. Thymocyte clones that have a high affinity for PTAs are eliminated by apoptosis in a process termed negative selection, which is essential for tolerance induction. The Aire gene is an important factor that controls the expression of a large set of PTAs. In addition to PTAs, Aire also controls the expression of miRNAs in mTECs. These miRNAs are important in the organization of the thymic architecture and act as posttranscriptional controllers of PTAs. Herein, we discuss recent discoveries and highlight open questions regarding the migration and interaction of developing thymocytes with thymic stroma, the ectopic expression of PTAs by mTECs, the association between Aire and miRNAs and its effects on central tolerance.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy: report of seven additional sicilian patients and overview of the overall series from sicily

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare recessive inherited disease caused by the mutation of the AIRE gene on chromosome 21. To date, 8 Sicilian patients have been described and the R203X AIRE mutation was found to be the most common in this region.

AIMS

(1) To describe 7 additional Sicilian APECED patients and to review all 15 Sicilian APECED patients who have been investigated by our group in the last years, and (2) to report a novel AIRE gene mutation.

RESULTS

Among the 3 cardinal features of APECED, hypoparathyroidism has been already detected in all 15 patients, whereas Addison's disease and chronic mucocutaneous candidiasis have so far been found in 10/15 and 12/15 cases, respectively. In 2 consanguineous cases, AIRE gene analysis revealed a novel mutation, named IVS13+2T, in homozygosis. R203X was the most common mutation in this region (30% of alleles and 46.6% of patients), followed by R257X (20% of alleles and 40% of patients).

CONCLUSIONS

Sicilian APECED patients are confirmed to have some peculiar characteristics from a clinical and genetic point of view. No correlations between genotype and phenotype were identified.

[The challenge for dermatologists of early APECED diagnosis]

BACKGROUND

Polyglandular auto-immune syndrome type 1 (PAS-1) or auto-immune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder linked to auto-immune regulator (AIRE) gene mutations. Herein, we report the case of a 3-year-old boy with APECED emphasizing the wide phenotypic variability and the extent of skin lesions.

PATIENTS AND METHODS

A 3-year-old boy with a history of auto-immune hepatitis was referred for a generalized pruriginous urticaria-like eruption present for one month. He was born to non-consanguineous parents. Cutaneous examination revealed twenty-nail dystrophy, which had been present since the age of 2 years. Both direct microscopy and culture of nail samples were negative for Candida albicans. Esophagogastroduodenoscopy revealed esophageal candidiasis. A diagnosis of APECED was suspected and subsequently confirmed by molecular analysis of the AIRE gene, which showed two mutations. No other auto-immune endocrinopathies were found.

DISCUSSION

Our case report illustrates the phenotypic variability of APECED with the absence of typical manifestations such as Addison's disease and hypoparathyroidism. APECED should thus be systematically suspected in young children presenting with cutaneous lesions associated with mucocutaneous candidiasis or auto-immune disease, even in the absence of known endocrinopathies.

CONCLUSION

Dermatologists should be aware of this association since early diagnosis of APECED is critical in preventing life-threatening endocrinological crises.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy from the pediatric perspective

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disease caused by mutations of the AutoImmune REgulator gene. The clinical spectrum of the disease encompasses several autoimmune endocrine and non-endocrine manifestations, which may lead to acute metabolic alterations and eventually life-threatening events. The clinical diagnosis is defined by the presence of at least two components of the classic triad including chronic mucocoutaneous candidiasis (CMC), chronic hypoparathyroidism (CH), Addison's disease (AD). Other common features of the disease are hypergonadotropic hypogonadism, alopecia, vitiligo, autoimmune hepatitis, Type 1 diabetes, gastrointestinal dysfunction. APECED usually begins in childhood. CMC is the first manifestation to appear, usually before the age of 5 yr, followed by CH and then by AD. The clinical phenotype may evolve over several years and many components of the disease may not appear until the 4th or 5th decade of life. The phenotypical expression of the syndrome shows a wide variability even between siblings with the same genotype. In view of this heterogeneity, an early diagnosis of APECED can be very challenging often leading to a considerable diagnostic delay. Therefore, clinicians should be aware that the presence of even a minor component of APECED in children should prompt a careful investigation for other signs and symptoms of the disease, thus allowing an early diagnosis and prevention of severe and life-threatening events. Aim of this review is to focus on clinical presentation, diagnosis and management of the major components of APECED in children particularly focusing on endocrine features of the disease.

APECED: A Paradigm of Complex Interactions between Genetic Background and Susceptibility Factors

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. Central tolerance takes place within the thymus and represents the mechanism by which potentially auto-reactive T-cells are eliminated through the negative selection process. The expression of tissue-specific antigens (TSAs) by medullary thymic epithelial cells (mTECs) in the thymus is a key process in the central tolerance and is driven by the protein encoded by AIRE gene, the transcription factor autoimmune regulator (AIRE). A failure in this process caused by AIRE mutations is thought to be responsible of the systemic autoimmune reactions of APECED. APECED is characterized by several autoimmune endocrine and non-endocrine manifestations and the phenotype is often complex. Although APECED is the paradigm of a monogenic autoimmune disorder, it is characterized by a wide variability of the clinical expression even between siblings with the same genotype, thus implying that additional mechanisms, other than the failure of Aire function, are involved in the pathogenesis of the disease. Unraveling open issues of the molecular basis of APECED, will help improve diagnosis, management, and therapeutical strategies of this complex disease.