Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome: A systematic review

IPEX syndrome from diagnosis to cure, learning along the way

In the past 2 decades, a significant number of studies have been published describing the molecular and clinical aspects of immune dysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome. These studies have refined our knowledge of this rare yet prototypic genetic autoimmune disease, advancing the diagnosis, broadening the clinical spectrum, and improving our understanding of the underlying immunologic mechanisms. Despite these advances, Forkhead box P3 mutations have devastating consequences, and treating patients with IPEX syndrome remains a challenge, even with safer strategies for hematopoietic stem cell transplantation and gene therapy becoming a promising reality. The aim of this review was to highlight novel features of the disease to further advance awareness and improve the diagnosis and treatment of patients with IPEX syndrome.

FOXP3 deficiency, from the mechanisms of the disease to curative strategies

FOXP3 gene is a key transcription factor driving immune tolerance and its deficiency causes immune dysregulation, polyendocrinopathy, enteropathy X-linked syndrome (IPEX), a prototypic primary immune regulatory disorder (PIRD) with defective regulatory T (Treg) cells. Although life-threatening, the increased awareness and early diagnosis have contributed to improved control of the disease. IPEX currently comprises a broad spectrum of clinical autoimmune manifestations from severe early onset organ involvement to moderate, recurrent manifestations. This review focuses on the mechanistic advancements that, since the IPEX discovery in early 2000, have informed the role of the human FOXP3+ Treg cells in controlling peripheral tolerance and shaping the overall immune landscape of IPEX patients and carrier mothers, contributing to defining new treatments.

Multilayer concept of autoimmune mechanisms and manifestations in inborn errors of immunity: Relevance for precision therapy

Autoimmunity in inborn errors of immunity (IEIs) has a multifactorial pathogenesis and develops subsequent to a genetic predisposition in conjunction with gene regulation, environmental modifiers, and infectious triggers. On the basis of incremental data availability owing to upfront application of omics technologies, a more granular and dynamic view of mechanisms and manifestations is warranted. Here, we present a comprehensive novel concept of autoimmunity in IEIs that considers multiple layers of interdependent elements and connects 101 causative genes or deletions according to the quality of the allelic variants with 47 molecular pathways and 22 immune effector mechanisms. Furthermore, we list 50 resulting manifestations together with the corresponding Human Phenotype Ontology terms and review the types and frequencies of the most relevant clinical presentations. When all of its elements are taken together, this concept (1) extends the historical anatomic view of central versus peripheral tolerance toward multiple interdependent mechanisms of immune tolerance, (2) delineates the mechanisms underlying the protean clinical manifestations, and thereby, (3) points toward the most suitable precision therapy for autoimmunity in IEIs. The multilayer concept of autoimmune mechanisms and manifestations in IEIs will facilitate research design and provide clinical guidance on the use of precision medicine irrespective of the data depth available in each health care scenario.

Inflammatory and Infectious Disorders in Endocrine Pathology

A variety of inflammatory conditions may directly involve the endocrine glands, leading to endocrine dysfunction that can cause severe consequences on patients' health, if left untreated. Inflammation of the endocrine system may be caused by either infectious agents or other mechanisms, including autoimmune and other immune-mediated processes. Not infrequently, inflammatory and infectious diseases may appear as tumor-like lesions of endocrine organs and simulate neoplastic processes. These diseases may be clinically under-recognized and not infrequently the diagnosis is suggested on pathological samples. Thus, the pathologist should be aware of the basic principles of their pathogenesis, as well as of their morphological features, clinicopathological correlates, and differential diagnosis. Interestingly, several systemic inflammatory conditions show a peculiar tropism to the endocrine system as a whole. In turn, organ-specific inflammatory disorders are observed in endocrine glands. This review will focus on the morphological aspects and clinicopathological features of infectious diseases, autoimmune disorders, drug-induced inflammatory reactions, IgG4-related disease, and other inflammatory disorders involving the endocrine system. A mixed entity-based and organ-based approach will be used, with the aim to provide the practicing pathologist with a comprehensive and practical guide to the diagnosis of infectious and inflammatory disorders of the endocrine system.

Too much of a good thing: a review of primary immune regulatory disorders

Primary immune regulatory disorders (PIRDs) are inborn errors of immunity caused by a loss in the regulatory mechanism of the inflammatory or immune response, leading to impaired immunological tolerance or an exuberant inflammatory response to various stimuli due to loss or gain of function mutations. Whilst PIRDs may feature susceptibility to recurrent, severe, or opportunistic infection in their phenotype, this group of syndromes has broadened the spectrum of disease caused by defects in immunity-related genes to include autoimmunity, autoinflammation, lymphoproliferation, malignancy, and allergy; increasing focus on PIRDs has thus redefined the classical 'primary immunodeficiency' as one aspect of an overarching group of inborn errors of immunity. The growing number of genetic defects associated with PIRDs has expanded our understanding of immune tolerance mechanisms and prompted identification of molecular targets for therapy. However, PIRDs remain difficult to recognize due to incomplete penetrance of their diverse phenotype, which may cross organ systems and present to multiple clinical specialists prior to review by an immunologist. Control of immune dysregulation with immunosuppressive therapies must be balanced against the enhanced infective risk posed by the underlying defect and accumulated end-organ damage, posing a challenge to clinicians. Whilst allogeneic hematopoietic stem cell transplantation may correct the underlying immune defect, identification of appropriate patients and timing of transplant is difficult. The relatively recent description of many PIRDs and rarity of individual genetic entities that comprise this group means data on natural history, clinical progression, and treatment are limited, and so international collaboration will be needed to better delineate phenotypes and the impact of existing and potential therapies. This review explores pathophysiology, clinical features, current therapeutic strategies for PIRDs including cellular platforms, and future directions for research.

Differential roles of regulatory T cells in acute respiratory infections

Acute respiratory infections trigger an inflammatory immune response with the goal of pathogen clearance; however, overexuberant inflammation causes tissue damage and impairs pulmonary function. CD4+FOXP3+ regulatory T cells (Tregs) interact with cells of both the innate and the adaptive immune system to limit acute pulmonary inflammation and promote its resolution. Tregs also provide tissue protection and coordinate lung tissue repair, facilitating a return to homeostatic pulmonary function. Here, we review Treg-mediated modulation of the host response to respiratory pathogens, focusing on mechanisms underlying how Tregs promote resolution of inflammation and repair of acute lung injury. We also discuss potential strategies to harness and optimize Tregs as a cellular therapy for patients with severe acute respiratory infection and discuss open questions in the field.

A Case Report of IPEX Syndrome with Neonatal Diabetes Mellitus and Congenital Hypothyroidism as the Initial Presentation, and a Systematic Review of neonatal IPEX

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX) is a serious disorder, which may comprise diabetes, thyroid disease, enteropathy, cytopenias, eczema, and other multi-system autoimmune dysfunction features. IPEX syndrome is caused by mutations in the forkhead box P3 (FOXP3) gene. Here, we report the clinical manifestations of a patient with IPEX syndrome onset in the neonatal period. A de novo mutation at exon 11 of the FOXP3 gene (c.1190G > A, p.R397Q) was found, and its main clinical manifestations included hyperglycemia and hypothyroidism. Subsequently, we comprehensively reviewed the clinical characteristics and FOXP3 mutations of 55 reported neonatal IPEX cases. The most frequent clinical presentation included symptoms of gastrointestinal involvement (n = 51, 92.7%), followed by skin-related symptoms (n = 37, 67.3%), diabetes mellitus (DM) (n = 33, 60.0%), elevated IgE (n = 28, 50.9%), hematological abnormality (n = 23, 41.8%), thyroid dysfunction (n = 18, 32.7%), and kidney-related symptoms (n = 13, 23.6%). In total, 38 variants were observed in the 55 neonatal patients. The most frequent mutation was c.1150G > A (n = 6; 10.9%), followed by c.1189C > T (n = 4; 7.3%), c.816 + 5G > A (n = 3; 5.5%), and C.1015C > G (n = 3; 5.5%), which were reported more than twice. The genotype-phenotype relationship showed that the repressor domain mutations were associated with DM (P = 0.020), and the leucine zipper mutations were associated with nephrotic syndrome (P = 0.020). The survival analysis suggested that treatment with glucocorticoids increased the survival of the neonatal patients. This literature review provides an informative reference for the diagnosis and treatment of IPEX syndrome in the neonatal period.

CTLA4-Ig Effectively Controls Clinical Deterioration and Immune Condition in a Murine Model of Foxp3 Deficiency

PURPOSE

FOXP3 deficiency results in severe multisystem autoimmunity in both mice and humans, driven by the absence of functional regulatory T cells. Patients typically present with early and severe autoimmune polyendocrinopathy, dermatitis, and severe inflammation of the gut, leading to villous atrophy and ultimately malabsorption, wasting, and failure to thrive. In the absence of successful treatment, FOXP3-deficient patients usually die within the first 2 years of life. Hematopoietic stem cell transplantation provides a curative option but first requires adequate control over the inflammatory condition. Due to the rarity of the condition, no clinical trials have been conducted, with widely unstandardized therapeutic approaches. We sought to compare the efficacy of lead therapeutic candidates rapamycin, anti-CD4 antibody, and CTLA4-Ig in controlling the physiological and immunological manifestations of Foxp3 deficiency in mice.

METHOD

We generated Foxp3-deficient mice and an appropriate clinical scoring system to enable direct comparison of lead therapeutic candidates rapamycin, nondepleting anti-CD4 antibody, and CTLA4-Ig.

RESULTS

We found distinct immunosuppressive profiles induced by each treatment, leading to unique protective combinations over distinct clinical manifestations. CTLA4-Ig provided superior breadth of protective outcomes, including highly efficient protection during the transplantation process.

CONCLUSION

These results highlight the mechanistic diversity of pathogenic pathways initiated by regulatory T cell loss and suggest CTLA4-Ig as a potentially superior therapeutic option for FOXP3-deficient patients.

The expanding spectrum and utility of antigens in membranous nephropathy

PURPOSE OF REVIEW

Multiple antigenic targets were discovered in membranous nephropathy, representing distinct autoimmune diseases with a similar morphologic pattern of injury. An overview of recent developments, including antigen types, clinical associations, serologic monitoring, and advancements in understanding disease pathogenesis are provided.

RECENT FINDINGS

Several new antigenic targets have defined subtypes of membranous nephropathy, including Neural epidermal growth factor-like 1, protocadherin 7, HTRA1, FAT1, SEMA3B, NTNG1, NCAM1, exostosin 1/2, transforming growth factor beta receptor 3, CNTN1, proprotein convertase subtilisin/kexin type 6, and neuron-derived neurotrophic factor. Autoantigens in membranous nephropathy may demonstrate unique clinical associations, assisting the nephrologist to identify potential disease etiologies and triggers, such as autoimmune disease, cancer, medications, and infections.

SUMMARY

We are entering an exciting era for which an antigen-based approach will further define subtypes of membranous nephropathy, allow for development of noninvasive diagnostics, and improve care for patients.

Autoimmune Polyendocrine Syndromes in the Pediatric Age

Autoimmune polyendocrine syndromes (APSs) encompass a heterogeneous group of rare diseases characterized by autoimmune activity against two or more endocrine or non-endocrine organs. Three types of APSs are reported, including both monogenic and multifactorial, heterogeneous disorders. The aim of this manuscript is to present the main clinical and epidemiological characteristics of APS-1, APS-2, and IPEX syndrome in the pediatric age, describing the mechanisms of autoimmunity and the currently available treatments for these rare conditions.

Advances in the potential roles of Cullin-RING ligases in regulating autoimmune diseases

Cullin-RING ligases (CRLs) are the largest class of E3 ubiquitin ligases regulating the stability and subsequent activity of a large number of important proteins responsible for the development and progression of various diseases, including autoimmune diseases (AIDs). However, the detailed mechanisms of the pathogenesis of AIDs are complicated and involve multiple signaling pathways. An in-depth understanding of the underlying regulatory mechanisms of the initiation and progression of AIDs will aid in the development of effective therapeutic strategies. CRLs play critical roles in regulating AIDs, partially by affecting the key inflammation-associated pathways such as NF-κB, JAK/STAT, and TGF-β. In this review, we summarize and discuss the potential roles of CRLs in the inflammatory signaling pathways and pathogenesis of AIDs. Furthermore, advances in the development of novel therapeutic strategies for AIDs through targeting CRLs are also highlighted.

Case Report: Single-stage facial reanimation with bilateral lengthening temporalis myoplasties for immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome related developmental facial palsy

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare primary immunodeficiency, typically associated with clinical features of intractable diarrhoea, type 1 diabetes mellitus and eczema. We present a case of IPEX syndrome referred to our regional facial palsy service for smile restoration surgery. The patient presented with dissatisfaction of facial appearance, including mask-like facies and no functional smile. Pre-operative electromyography confirmed normal temporalis muscle activation. Consequently, the patient was offered single-stage bilateral lengthening temporalis myoplasties. The patient reported improved satisfaction with facial appearance. Surgery resulted in good early resting and voluntary symmetry. Oral commissures were elevated at rest improving oral incompetence. This is the first description of facial animation surgery in the context of IPEX syndrome. With careful consideration and patient selection, successful surgical restoration of resting symmetry and dynamic commissural smile can be achieved in this complex cohort of patients.

Immune dysregulation, polyendocrinopathy and enteropathy, X-linked (IPEX) syndrome due to a mutation in FOXP3, modified by a pathogenic variant in SON (SON DNA-binding protein)

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked, known as IPEX syndrome, is a rare heterogeneous condition. Zhu-Tokita-Takenouchi-Kim Syndrome (ZTTK) is an autosomal dominant condition arising from a mutation in the SON gene, which is involved in mRNA splicing. A case showing interactions of mutations in these two genes is described in which both conditions become non-typical.

Gene Editing in Human Haematopoietic Stem Cells for the Treatment of Primary Immunodeficiencies

In recent years, gene-editing technologies have revolutionised precision medicine, and human trials of this technology have been reported in cell-based cancer therapies and other genetic disorders. The same techniques have the potential to reverse mutations in monogenic primary immunodeficiencies (PIDs), and transplantation of edited haematopoietic stem cells may provide a functional cure for these diseases. In this review, we discuss the methods of gene editing being explored and describe progress made so far with several PIDs. We also detail the remaining challenges, how to confidently detect off-target effects and chromosomal abnormalities in a timely manner, how to obtain long-term benefits, and how to achieve physiological levels of expression of the therapeutic gene. With advances in gene editing, we envisage a robust clinical translation of this technology in the coming decade.

Impaired Treg-DC interactions contribute to autoimmunity in leukocyte adhesion deficiency type 1

Leukocyte adhesion deficiency type 1 (LAD-1) is a rare disease resulting from mutations in the gene encoding for the common β-chain of the β2-integrin family (CD18). The most prominent clinical symptoms are profound leukocytosis and high susceptibility to infections. Patients with LAD-1 are prone to develop autoimmune diseases, but the molecular and cellular mechanisms that result in coexisting immunodeficiency and autoimmunity are still unresolved. CD4+FOXP3+ Treg are known for their essential role in preventing autoimmunity. To understand the role of Treg in LAD-1 development and manifestation of autoimmunity, we generated mice specifically lacking CD18 on Treg (CD18Foxp3), resulting in defective LFA-1 expression. Here, we demonstrate a crucial role of LFA-1 on Treg to maintain immune homeostasis by modifying T cell-DC interactions and CD4+ T cell activation. Treg-specific CD18 deletion did not impair Treg migration into extralymphatic organs, but it resulted in shorter interactions of Treg with DC. In vivo, CD18Foxp3 mice developed spontaneous hyperplasia in lymphatic organs and diffuse inflammation of the skin and in multiple internal organs. Thus, LFA-1 on Treg is required for the maintenance of immune homeostasis.

Underlying IPEX syndrome in a patient with idiopathic juvenile arthritis and vitiligo

BACKGROUND

IPEX syndrome is an X-linked inborn error of immunity clinically characterized by the triad of: enteropathy, polyendocrinopathy and eczema. However many other clinical presentations lacking the triad above described have been reported what underpin the need of careful clinical suspicion, immunological evaluation and genetic sequencing.

CASE PRESENTATION

Here we report a case of a Brazilian boy with severe eczema as the first and only presentation requiring cyclosporin therapy. Progressive and cumulative symptoms of arthritis and enteropathy lead to the suspicion of an inborn error of immunity. Peripheral FOXP3 expression was normal (CD127-/CD4+/CD25+/FOXP3+-396 cells-63%) and a pathogenic mutation in FOXP3 gene (c.1150G>A; p.Ala384Thr), confirmed the diagnosis of IPEX syndrome.

CONCLUSIONS

IPEX syndrome should be suspected in patients presenting with severe eczema associated or not with other autoimmune/hyper inflammatory diseases in life. Our study also reinforces that FOXP3 expression by flowcytometry seems not to be a good screening method, and genetic sequencing is mandatory even in those with high suspicion and normal peripheral FOXP3 expression.

The role behind the scenes of Tregs and Th17s in Hashimoto's thyroiditis: Toward a pivotal role of FOXP3 and BACH2

In Hashimoto's thyroiditis (HT), the genetic bases play a central role in determining development of the disease. In particular, the most frequent genes involved in the onset of HT are the Human Leukocyte Antigen (HLA). However, there are other genes and transcription factors in the autoimmune background of HT, both isolated and as part of autoimmune polyendocrine syndromes (APS). Recently more interest is being fueled toward BACH2 (BTB Domain and CNC Homolog 2), that promotes Tregs (T regulators lymphocytes) differentiation and enhances Treg-mediated immunity. The synergistic interaction between environmental agents and the aforementioned genes leads to the onset of autoimmunity and ultimately to damage of the thyroid gland. In this scenario, the role of Th17 (T helper-17 lymphocytes) and Treg cells is still less defined as compared to action of Th1 cells (T helper-1 lymphocytes) and cytotoxic lymphocytes (CD8 ⁺ T lymphocytes). Evidences show that an imbalance of Th17/Treg ratio represents a prognostic factor with respect to the gland damage. Moreover, the deficient ability of Treg to inhibit the proliferation of T cells against the self can break the immune balance. In light of these considerations, the use of genetic panels and the progress of immunotherapy could allow for better targeting treatment and preventive interventions in subjects with potential or early stage of HT.

Atopic Dermatitis-like Genodermatosis: Disease Diagnosis and Management

Eczema is a classical characteristic not only in atopic dermatitis but also in various genodermatosis. Patients suffering from primary immunodeficiency diseases such as hyper-immunoglobulin E syndromes, Wiskott-Aldrich syndrome, immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, STAT5B deficiency, Omenn syndrome, atypical complete DiGeorge syndrome; metabolic disorders such as acrodermatitis enteropathy, multiple carboxylase deficiency, prolidase deficiency; and other rare syndromes like severe dermatitis, multiple allergies and metabolic wasting syndrome, Netherton syndrome, and peeling skin syndrome frequently perform with eczema-like lesions. These genodermatosis may be misguided in the context of eczematous phenotype. Misdiagnosis of severe disorders unavoidably affects appropriate treatment and leads to irreversible outcomes for patients, which underlines the importance of molecular diagnosis and genetic analysis. Here we conclude clinical manifestations, molecular mechanism, diagnosis and management of several eczema-related genodermatosis and provide accessible advice to physicians.

Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-linked Syndrome in Two Siblings: Same Mutation But Different Clinical Manifestations at Onset

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is an early onset systemic autoimmune genetic disorder caused by mutation of the forkhead box protein 3 (FOXP3) gene. Enteropathy, endocrinopathy and skin manifestations are considered the classic triad of IPEX syndrome. However, patients with IPEX syndrome display a variety of phenotypes including life threatening multi-organ autoimmunity. Here, we present the case of two siblings with IPEX syndrome with the same hemizygous mutation, but with different types of symptomology at onset of the disease.

Clinical and immunological characteristics of five patients with immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome in China–expanding the atypical phenotypes

Background

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare disorder of the immune regulatory system caused by forkhead box P3 (FOXP3) mutations. Abnormal numbers or functions of regulatory T (Treg) cells account for the various autoimmune symptoms. We aimed to explore the molecular genetics and phenotypic spectra of patients with atypical IPEX syndrome in China.

Methods

We analyzed the molecular, clinical and immune phenotype characteristics of five Chinese patients with FOXP3 mutations.

Results

We summarized the molecular and phenotypic features of five patients with FOXP3 mutations, including two novel mutations. Four of the five patients displayed atypical phenotypes, and one developed immune-related peripheral neuropathy. Three of the five patients showed normal frequencies of Treg cells, but the proportions of subsets of Treg cells, CD4⁺ T cells and B cells were out of balance.

Conclusions

Our report broadens the understanding of the clinical features of atypical IPEX syndrome. Our detailed analyses of the immunological characteristics of these patients enhance the understanding of the possible mechanisms underlying the clinical manifestations.

Atopic dermatitis leading to failure to thrive: A case report

We present an infant with severe atopic dermatitis, protein loss, and subsequent failure to thrive. With proper management, the patient's laboratory findings normalized, and he gained weight appropriately. In this report, we highlight the impact that severe atopic dermatitis may have growth and development and review the genetic conditions that can result in a similar clinical presentation.

A novel FOXP3 mutation in a Chinese child with IPEX-associated membranous nephropathy

BACKGROUND

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a monogenic immunodeficiency disease caused by forkhead box protein3 (FOXP3) mutation. The kidney is commonly involved in IPEX syndrome, but there were few studies focusing on renal involvement.

METHODS

Whole-exome sequencing was used to identify the novel FOXP3 mutation. We collected clinical manifestations, kidney pathology, and gene function of the proband. All the previously published studies with IPEX-associated renal involvement were reviewed.

RESULTS

We report a late-onset Chinese child with IPEX-associated membranous nephropathy (MN). Type 1 diabetes mellitus and nephrotic-range proteinuria are the main clinical manifestations. Whole-exome sequencing shows a novel c.766A > G mutation in the FOXP3 gene. The literature review indicates that renal manifestations include proteinuria, microscopic hematuria, and renal insufficiency. MN is the most common pathological type in children with IPEX, followed by tubulointerstitial nephritis, interstitial nephritis, minimal change nephrotic syndrome, and membranoproliferative glomerulonephritis.

CONCLUSION

In summary, we report a novel FOXP3 mutation (c.766A > G) with MN stage II in IPEX. In a literature review, MN is the most common pathological type in children with IPEX and proteinuria is the most prevalent clinical feature. IPEX should be considered in the differential diagnosis of MN patients with related endocrine diseases and immune disorders.

Inborn Errors of Immunity Associated With Type 2 Inflammation in the USIDNET Registry

Background

Monogenic conditions that disrupt proper development and/or function of the immune system are termed inborn errors of immunity (IEIs), also known as primary immunodeficiencies. Patients with IEIs often suffer from other manifestations in addition to infection, and allergic inflammation is an increasingly recognized feature of these conditions.

Methods

We performed a retrospective analysis of IEIs presenting with allergic inflammation as reported in the USIDNET registry. Our inclusion criteria comprised of patients with a reported monogenic cause for IEI where reported lab eosinophil and/or IgE values were available for the patient prior to them receiving potentially curative therapy. Patients were excluded if we were unable to determine the defective gene underlying their IEI. Patients were classified as having eosinophilia or elevated IgE when their record included at least 1 eosinophil count or IgE value that was greater than the age stratified upper limit of normal. We compared the proportion of patients with eosinophilia or elevated IgE with the proportion of samples in a reference population that fall above the upper limit of normal (2.5%).

Results

The query submitted to the USIDNET registry identified 1409 patients meeting inclusion criteria with a monogenic cause for their IEI diagnosis, of which 975 had eosinophil counts and 645 had IgE levels obtained prior to transplantation or gene therapy that were available for analysis. Overall, 18.8% (183/975) of the patients evaluated from the USIDNET registry had eosinophilia and 20.9% (135/645) had an elevated IgE. IEIs caused by defects in 32 genes were found to be significantly associated with eosinophilia and/or an elevated IgE level, spanning 7 of the 10 IEI categories according to the International Union of Immunological Societies classification.

Conclusion

Type 2 inflammation manifesting as eosinophilia or elevated IgE is found in a broad range of IEIs in the USIDNET registry. Our findings suggest that allergic immune dysregulation may be more widespread in IEIs than previously reported.

The role of genetics in food allergy

INTRODUCTION

As the prevalence of food allergies (FA) increases worldwide, our understanding of its pathophysiology and risk factors is markedly expanding. In the past decades, an increasing number of genes have been linked to FA. Identification of such genes may help in predicting the genetic risk for FA development, age of onset, clinical manifestation, causative allergen(s), and possibly the optimal treatment strategies. Furthermore, identification of these genetic factors can help to understand the complex interactions between genes and the environment in predisposition to FA.

AREAS COVERED

We outline the recent important progress in determining genetic variants and disease-associated genes in IgE-mediated FA. We focused on the monogenic inborn errors of immunity (IEI) where FA is one of the clinical manifestations, emphasizing the genes and gene variants which were linked to FA with some of the most robust evidence.

EXPERT OPINION

Genetics play a significant role, either directly or along with environmental factors, in the development of FA. Since FA is a multifactorial disease, it is expected that multiple genes and genetic loci contribute to the risk for its development. Identification of the involved genes should contribute to the area of FA regarding pathogenesis, prediction, recognition, prognosis, prevention, and possibly therapeutic interventions.

Primary immune regulatory disorders: Undiagnosed needles in the haystack?

Primary Immune Regulatory Disorders (PIRD) describe a group of conditions characterized by loss of normal inflammatory control and immune tolerance mechanisms, with autoimmunity as a predominant clinical feature. PIRD can arise due to defects in the number or function of regulatory T-lymphocytes, defects in the immune mechanisms required to ‘turn off’ inflammation such as in perforin-dependent cytotoxicity or alterations in cytokine signalling pathways. Diagnosis of PIRD is a significant challenge to physicians due to their rarity, complexity, and diversity in clinical manifestations. Many of these individual conditions lack a genotype–phenotype correlation and display incomplete penetrance. However, establishing a diagnosis is integral in optimizing patient management, including the use of individualized treatment approaches. Increasing awareness among physicians is necessary as patients are likely to present to different subspecialties. Due to the rarity of these conditions, worldwide collaboration and data-sharing is essential to improve our knowledge of the clinical spectrum and disease course in PIRD, and to optimize therapeutic strategies including identification of which patients can benefit from hematopoietic stem cell transplant.

Renal Involvement in IPEX Syndrome With a Novel Mutation of FOXP3: A Case Report

The immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare genetic disease characterized by multiple immune disorders. Different mutations of the FOXP3 gene may lead to distinct clinical manifestations. Here, we present a rare case of IPEX syndrome caused by a novel variant of FOXP3. Clinical manifestations include autoimmune hemolysis, bronchiectasis, diarrhea, and proteinuria but without diabetes or other endocrine disorders. The diagnosis of IPEX syndrome was confirmed by whole-exon sequencing. Supportive treatment did not ameliorate the patient’s symptoms, while immunosuppressive therapy showed a promising efficacy. The patient we reported will improve the understanding of renal manifestations in IPEX syndrome.

Immune‐mediated inflammatory diseases of the gastrointestinal tract: Beyond Crohn's disease and ulcerative colitis

Immune‐mediated inflammatory diseases (IMIDs) are a diverse group of complex inflammatory diseases that result from dysregulated immune pathways and can involve any system of the human body. Inflammatory bowel disease (IBD) is one such disease involving the gastrointestinal (GI) system. With high prevalence in the West and increasing incidence in newly industrialized countries, IBD poses a significant burden on health care. IMIDs of the GI system other than IBD can have similar clinical features, causing diagnostic and therapeutic challenges. Although these disorders share a common pathophysiology, the defects can occur anywhere in the complex network of cytokines, inflammatory mediators, and innate and adaptive systems, leading to unregulated inflammation. Precise knowledge about them will help determine the possible targeted therapy. Thus, it is essential to distinguish these disorders from IBD. This review describes various IMIDs of the GI tract that mimic IBD.

Inborn Errors of Immunity With Fetal or Perinatal Clinical Manifestations

In this article we revised the literature on Inborn Errors of Immunity (IEI) keeping our focus on those diseases presenting with intrauterine or perinatal clinical manifestations. We opted to describe our findings according to the IEI categories established by the International Union of Immunological Societies, predominantly addressing the immunological features of each condition or group of diseases. The main finding is that such precocious manifestations are largely concentrated in the group of primary immune regulatory disorders (PIRDs) and not in the group of classical immunodeficiencies. The IEI categories with higher number of immunological manifestations in utero or in perinatal period are: (i) diseases of immune dysregulation (HLH, IPEX and other Tregopathies, autosomal recessive ALPS with complete lack of FAS protein expression) and (ii) autoinflammatory diseases (NOMID/CINCA, DIRA and some interferonopathies, such as Aicardi-Goutières syndrome, AGS, and USP18 deficiency). Regarding the other IEI categories, some patients with Omenn syndrome (an atypical form of SCID), and a few X-linked CGD patients present with clinical manifestations at birth associated to immune dysregulation. The most frequent clinical features were hydrops fetalis, intrauterine growth retardation leading to fetal loss, stillbirths, and prematurity, as in HLH and IPEX. Additionally, pseudo-TORCH syndrome was observed in AGS and in USP18 deficiency. The main goal of our review was to contribute to increasing the medical awareness of IEI with intrauterine and perinatal onset, which has obvious implications for diagnosis, treatment, and genetic counseling.

Endocrinopathies in Inborn Errors of Immunity

Inborn errors of immunity (IEI), caused by hereditary or genetic defects, are a group of more than 400 disorders, in which the immune system, including lymphocytes, neutrophils, macrophages, and complements, does not function properly. The endocrine system is frequently affected by IEI as an associated clinical feature and a complex network of glands which regulate many important body functions, including growth, reproduction, homeostasis, and energy regulation. Most endocrine disorders associated with IEI are hypofunction which would be treated with supplementation therapy, and early diagnosis and appropriate management are essential for favorable long-term outcomes in patients with IEI. In this review, we aimed to comprehensively summarize and discuss the current understanding on the clinical features and the pathophysiology of endocrine disorders in IEI. This review is composed with three parts. First, we discuss the two major pathophysiology of endocrinopathy in IEI, autoimmune response and direct effects of the responsible genes. Next, the details of each endocrinopathy, such as growth failure, hypothyroidism, hypoparathyroidism, adrenal insufficiency, diabetes mellitus (DM) are specified. We also illustrated potential endocrinopathy due to hematopoietic stem cell transplantation, including hypogonadism and adrenal insufficiency due to glucocorticoid therapy.

Pediatric Autoimmune Liver Diseases: Autoimmune Hepatitis and Primary Sclerosing Cholangitis

In chronic hepatitis, a broad differential diagnosis should be considered to accurately identify the cause(s) of liver injury. Autoimmune liver diseases (autoimmune hepatitis, primary sclerosing cholangitis, overlap syndrome) can occur in the setting of limited symptoms; therefore, a high index of suspicion and appropriate diagnostic workup should be performed. Most children with autoimmune hepatitis achieve sustained remission with medical therapy; however, there are no equivalent therapies for primary sclerosing cholangitis that impact the progression of disease. Research should include biomarker studies to predict histologic remission in autoimmune hepatitis and mechanistic studies to define future treatment targets for primary sclerosing cholangitis.

The mosaic of autoimmunity - A taste for more. The 12th international congress of autoimmunity 2021 (AUTO12) virtual

Notwithstanding the fact that the 12th international congress of autoimmunity (AUTO12) was held virtual this year, the number of the abstracts submitted and those presented crossed the thousand marks. Leading investigators and researchers from all over the world presented the latest developments of their research in the domain of autoimmunity and its correlation with various diseases. In terms of mechanisms of autoimmunity, an update on the mechanisms behind the association of autoimmunity with systemic diseases focusing on hyperstimulation was presented during AUTO12. In addition, a new mechanism of ASIA syndrome caused by an intrauterine contraceptive device was revealed demonstrating a complete resolution of symptoms following device removal. In regard to the correlation between autoimmunity and neurogenerative diseases, the loss of structural protein integrity as the trigger of immunological response was shown. Schizophrenia as well, and its correlation to pro-inflammatory cytokines was also addressed. Furthermore, and as it was said AUTO12 virtual due to COVID-19 pandemic, various works were dedicated to SARS-CoV-2 infection and COVID-19 in terms of autoimmune mechanisms involved in the pathogenesis, treatment and complications of COVID-19. For instance, the correlation between autoimmunity and the severity of COVID-19 was viewed. Moreover, the presence and association of autoantibodies in COVID-19 was also demonstrated, as well as the clinical outcomes of COVID-19 in patients with rheumatic diseases. Finally, immune-mediated reactions and processes secondary to SARS-CoV-2 vaccination was displayed. Due to the immense importance of all of the topics addressed and while several hundreds of works were presented which cannot be summed up in one paper, we aimed hereby to highlight some of the outstanding abstracts and presentations during AUTO12.

Regulatory T cells function in established systemic inflammation and reverse fatal autoimmunity

The immunosuppressive function of regulatory T (Treg) cells is dependent on continuous expression of the transcription factor Foxp3. Foxp3 loss-of-function or induced ablation of Treg cells results in a fatal autoimmune disease featuring all known types of inflammatory responses with every manifestation stemming from Treg cell paucity, highlighting a vital function of Treg cells in preventing fatal autoimmune inflammation. However, a major question remains whether Treg cells can persist and effectively exert their function in a disease state, where a broad spectrum of inflammatory mediators can either inactivate Treg cells or render innate and adaptive pro-inflammatory effector cells insensitive to suppression. By reinstating Foxp3 protein expression and suppressor function in cells expressing a reversible Foxp3 null allele in severely diseased mice, we found that the resulting single pool of “redeemed” Treg cells normalized immune activation, quelled severe tissue inflammation, reversed fatal autoimmune disease, and provided long-term protection against them. Thus, Treg cells are functional in settings of established broad spectrum systemic inflammation and are capable of affording sustained reset of immune homeostasis.

Familial Clustering of Juvenile Psoriatic Arthritis Associated with a Hemizygous FOXP3 Mutation

PURPOSE OF REVIEW

We describe the clinical and genetic findings in four patients from a single family who presented with refractory psoriatic arthritis and were hemizygous in the forkhead box protein 3 (FOXP3) gene (c.1222G>A).

RECENT FINDINGS

We report four siblings with hemizygous mutation in the FOXP3 gene (c.1222G>A) who presented with type 1 diabetes mellitus and psoriatic arthritis poorly responsive to treatment. Our findings expand the phenotype spectrum of FOXP3 mutations. Immune dysregulation, polyendocrinopathy, and enteropathy, X-linked (IPEX) syndrome is a rare disorder caused by mutations in FOXP3 gene, which lead to early onset of constellation of autoimmune manifestations. This report highlights the influence of immune dysregulation in juvenile arthritis.

Lymphadenopathy at the crossroad between immunodeficiency and autoinflammation: An intriguing challenge

Lymphadenopathies can be part of the clinical spectrum of several primary immunodeficiencies, including diseases with immune dysregulation and autoinflammatory disorders, as the clinical expression of benign polyclonal lymphoproliferation, granulomatous disease or lymphoid malignancy. Lymphadenopathy poses a significant diagnostic dilemma when it represents the first sign of a disorder of the immune system, leading to a consequently delayed diagnosis. Additionally, the finding of lymphadenopathy in a patient with diagnosed immunodeficiency raises the question of the differential diagnosis between benign lymphoproliferation and malignancies. Lymphadenopathies are evidenced in 15–20% of the patients with common variable immunodeficiency, while in other antibody deficiencies the prevalence is lower. They are also evidenced in different combined immunodeficiency disorders, including Omenn syndrome, which presents in the first months of life. Interestingly, in the activated phosphoinositide 3‐kinase delta syndrome, autoimmune lymphoproliferative syndrome, Epstein–Barr virus (EBV)‐related lymphoproliferative disorders and regulatory T cell disorders, lymphadenopathy is one of the leading signs of the entire clinical picture. Among autoinflammatory diseases, the highest prevalence of lymphadenopathies is observed in patients with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) and hyper‐immunoglobulin (Ig)D syndrome. The mechanisms underlying lymphoproliferation in the different disorders of the immune system are multiple and not completely elucidated. The advances in genetic techniques provide the opportunity of identifying new monogenic disorders, allowing genotype–phenotype correlations to be made and to provide adequate follow‐up and treatment in the single diseases. In this work, we provide an overview of the most relevant immune disorders associated with lymphadenopathy, focusing on their diagnostic and prognostic implications.

Search for Genetic Predictors of Adult Autoimmune Polyendocrine Syndrome in Monozygotic Twins

Autoimmune polyendocrine syndromes (APS) are a heterogeneous group of diseases characterized by the presence of autoimmune dysfunction of 2 or more endocrine glands and other non-endocrine organs. The components of the syndrome can manifest throughout life: in childhood—APS type 1 (the juvenile type) and in adulthood—APS type 2, 3, and 4 (the adult types). Adult types of APS are more common in clinical practice. It is a polygenic disease associated with abnormalities in genes encoding key regulatory proteins of the major histocompatibility complex (MHC). The search of for candidate genes responsible for mutations in adult APS is continuing. Genetic predisposition is insufficient for the manifestation of the APS of adults, since the penetrance of the disease, even among monozygotic twins, does not approach 100% (30–70%). The article presents the case of isolated Addison’s disease and APS type 2 in monozygotic twins with a revealed compound heterozygosity in the candidate gene VTCN1.

Cellular and molecular mechanisms breaking immune tolerance in inborn errors of immunity

In addition to susceptibility to infections, conventional primary immunodeficiency disorders (PIDs) and inborn errors of immunity (IEI) can cause immune dysregulation, manifesting as lymphoproliferative and/or autoimmune disease. Autoimmunity can be the prominent phenotype of PIDs and commonly includes cytopenias and rheumatological diseases, such as arthritis, systemic lupus erythematosus (SLE), and Sjogren's syndrome (SjS). Recent advances in understanding the genetic basis of systemic autoimmune diseases and PIDs suggest an at least partially shared genetic background and therefore common pathogenic mechanisms. Here, we explore the interconnected pathogenic pathways of autoimmunity and primary immunodeficiency, highlighting the mechanisms breaking the different layers of immune tolerance to self-antigens in selected IEI.

Immune checkpoint deficiencies and autoimmune lymphoproliferative syndromes

Autoimmune lymphoproliferative syndrome (ALPS) is an inherited non-malignant and non-infectious lymphoproliferative syndrome caused by mutations in genes affecting the extrinsic apoptotic pathway (FAS, FASL, CASP10). The resulting FAS-mediated apoptosis defect accounts for the expansion and accumulation of autoreactive (double-negative) T cells leading to cytopenias, splenomegaly, lymphadenopathy, autoimmune disorders, and risk of lymphoma. However, there are other monogenetic disorders known as ALPS-like syndromes that can be clinically similar to ALPS but are genetically and biologically different, such as observed in patients with immune checkpoint deficiencies, particularly cytotoxic T-lymphocyte antigen 4 (CTLA-4) insufficiency and lipopolysaccharide-responsive beige-like anchor protein LRBA deficiency. CTLA-4 insufficiency is caused by heterozygous mutations in CTLA-4, an essential negative immune regulator that is constitutively expressed on regulatory T (Treg) cells. Mutations in CTLA-4 affect CTLA-4 binding to CD80-CD86 costimulatory molecules, CTLA-4 homodimerization, or CTLA-4 intracellular vesicle trafficking upon cell activation. Abnormal CTLA-4 trafficking is also observed in patients with LRBA deficiency, a syndrome caused by biallelic mutations in LRBA that abolishes the LRBA protein expression. Both immune checkpoint deficiencies are biologically characterized by low levels of CTLA-4 protein on the cell surface of Tregs, accounting for the autoimmune manifestations observed in CTLA4-insufficient and LRBA-deficient patients. In addition, both immune checkpoint deficiencies present with an overlapping but heterogeneous clinical picture despite the difference in inheritance and penetrance. In this review, we describe the most prominent clinical features of ALPS, CTLA-4 insufficiency and LRBA deficiency, emphasizing their corresponding biological mechanisms. We also provide some clinical and laboratory approaches to diagnose these three rare immune disorders, together with therapeutic strategies that have worked best at improving prognosis and quality life of patients.

Genetics of Food Allergy

The risk factors for food allergy (FA) include both genetic variants and environmental factors. Advances using both candidate-gene association studies and genome-wide approaches have led to the identification of FA-associated genes involved in immune responses and skin barrier functions. Epigenetic changes have also been associated with the risk of FA. In this chapter, we outline current understanding of the genetics, epigenetics and the interplay with environmental risk factors associated with FA. Future studies of gene-environment interactions, gene-gene interactions, and multi-omics integration may help shed light on the mechanisms of FA, and lead to improved diagnostic and treatment strategies.

A delayed diagnosis of atypical immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome: A case report

INTRODUCTION

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked (IPEX) syndrome is a rare monogenic autoimmune disease, which is caused by mutations in the forkhead box protein 3 gene, can affect various systems. The typical clinical manifestations of IPEX are enteropathy, type 1 diabetes mellitus, and skin diseases. However, some atypical phenotypes can easily be misdiagnosed clinically.

PATIENT CONCERNS

A 9-year-and-7-month old patient suffered from recurrent wheezing, hematochezia, and eczematous dermatitis at the age of six months, but did not have any manifestations of autoimmune endocrinopathy. The patient was treated with glucocorticoids for more than six years, and he developed bronchiectasis.

DIAGNOSIS

Whole exome sequencing revealed a hemizygous pathogenic mutation c.1010G>A, p. (Arg337Gln) in Forkhead box protein 3 gene (NM_014009.3).

INTERVENTIONS

The patient was treated with oral mycophenolate mofetil combined with inhaled budesonide formoterol for six months after diagnosis.

OUTCOMES

The respiratory symptoms of the patient seemed to be controlled but eczematous dermatitis progressed, which led the patient to give up the treatment.

CONCLUSION

Early diagnosis and treatment of IPEX are crucial. Lung injury may be a major problem in the later stages of atypical IPEX, and mycophenolate mofetil seems to control the respiratory symptoms, but could induce significant skin side effects.

IPEX Syndrome: Genetics and Treatment Options

(1) Background: IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked) syndrome characterizes a complex autoimmune reaction beginning in the perinatal period, caused by a dysfunction of the transcription factor forkhead box P3 (FOXP3). (2) Objectives: Studies have shown the clinical, immunological, and molecular heterogeneity of patients with IPEX syndrome. The symptoms, treatment, and survival were closely connected to the genotype of the IPEX syndrome. Recognition of the kind of mutation is important for the diagnostics of IPEX syndrome in newborns and young infants, as well as in prenatal screening. The method of choice for treatment is hematopoietic stem cell transplantation and immunosuppressive therapy. In children, supportive therapy for refractory diarrhea is very important, as well as replacement therapy of diabetes mellitus type 1 (DMT1) and other endocrinopathies. In the future, genetic engineering methods may be of use in the successful treatment of IPEX syndrome. (3) Conclusions: The genetic defects determine a diagnostic approach and prognosis, making the knowledge of the genetics of IPEX syndrome fundamental to introducing novel treatment methods.

IPEX Syndrome: Improved Knowledge of Immune Pathogenesis Empowers Diagnosis

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare monogenic autoimmune disease with variable clinical manifestations, ranging from early-onset severe autoimmunity, including enteropathy, eczema, and type 1 diabetes, to late-onset or atypical symptoms. Despite the clinical heterogeneity, the unifying feature of IPEX is mutation of the FOXP3 gene, which encodes a transcription factor essential for maintenance of thymus-derived regulatory T cells (Tregs). In IPEX patients, Tregs can be present, although unstable and impaired in function, unable to inhibit proliferation and cytokine production of effector T (Teff) cells. Mutated FOXP3 can also disrupt other compartments: FOXP3-deficient Teff cells proliferate more than the wild-type counterpart, display altered T-cell-receptor signaling response, a reduced T-naïve compartment and a skew toward a Th2 profile. Due to FOXP3 mutations, the frequency of autoreactive B cells is increased and the IgA and IgE production is altered, together with early emergence of tissue-specific autoantibodies. Recently, the awareness of the wide clinical spectrum of IPEX improved the diagnostic tools. In cases presenting with enteropathy, histological evaluation is helpful, although there are no pathognomonic signs of disease. On the other hand, the study of FOXP3 expression and in vitro Treg function, as well as the detection of specific circulating autoantibodies, is recommended to narrow the differential diagnosis. Nowadays, Sanger sequencing should be limited to cases presenting with the classical triad of symptoms; otherwise, next-generation sequencing is recommended, given the cost-effectiveness and the advantage of excluding IPEX-like syndromes. The latter approach could be time spearing in children with severe phenotypes and candidate to advanced therapies.

Regulatory T cell heterogeneity and therapy in autoimmune diseases

Regulatory T (Treg) cells are a group of CD4⁺ T cell with high expression of CD25 and cell linage specific transcription factor forkhead box P3 (Foxp3) and play a vital role in maintaining immune homeostasis. In the last two decades, researchers have shown that Treg cells involved in the occurrence, development and prognosis of many diseases, especially in autoimmune diseases. Treg targeted therapies, such as low-dose interleukin-2 (IL-2) treatment and Treg infusion therapy, which are aimed at restoring the number or function of Treg cells, have become a hot topic in clinical trials of these diseases. It is believed that Treg cells are heterogeneous. Different subsets of Treg cells have various functions and play different parts in immunomodulatory. Gaining insights into Treg heterogeneity will help us further understand the function of Treg cells and provide news ideas for the selective therapeutic manipulation of Treg cells. In this review, we mainly summarize the heterogeneity of Treg cells and their potential therapeutic value in autoimmune diseases.

Bibliometric Analysis on COVID-19: A Comparison of Research Between English and Chinese Studies

Background: As an emerging infectious disease, COVID-19 has garnered great research interest. We aimed to explore the differences between English language and Chinese language Medical/Scientific journals publications, particularly aiming to explore the efficacy/contents of the literature published in English and Chinese in relation to the outcomes of management and characterization of COVID-19 during the early stage of COVID-19 pandemic.

Methods: Publications on COVID-19 research were retrieved from both English and Chinese databases. Bibliometric analyses were performed using VOSviewer 1.6.14, and CiteSpace V software. Network maps were generated to evaluate the collaborations between different authors, countries/provinces, and institutions.

Results: A total of 143 English and 721 Chinese original research articles and reviews on COVID-19 were included in our study. Most of the authors and institutions of the papers were from China before March 1st, 2020, however, the distribution of authors and institutions were mainly in developed countries or more wealthy areas of China. The range of the keywords in English publications was more extensive than those in Chinese. Traditional Chinese Medicine was seen more frequently in Chinese papers than in English. Of the 143 articles published in English, 54 articles were published by Chinese authors only and 21 articles were published jointly by Chinese and other overseas authors.

Conclusions: The publications in English have enabled medical practitioners and scientists to share/exchange information, while on the other hand, the publications in the Chinese language have provided complementary educational approaches for the local medical practitioners to understand the essential and key information to manage COVID-19 in the relatively remote regions of China, for the general population with a general level of education.

Intrauterine IPEX

IPEX is one of the few Inborn Errors of Immunity that may manifest in the fetal period, and its intrauterine forms certainly represent the earliest human autoimmune diseases. Here, we review the clinical, histopathologic, and genetic findings from 21 individuals in 11 unrelated families, with nine different mutations, described as cases of intrauterine IPEX. Recurrent male fetal death (multigenerational in five families) due to hydrops in the midsemester of pregnancy was the commonest presentation (13/21). Noteworthy, in the affected families, there were only fetal- or perinatal-onset cases, with no affected individuals presenting milder forms with later-life manifestation. Most alive births were preterm (5/6). Skin desquamation and intrauterine growth restriction were observed in part of the cases. Fetal ultrasonography showed hyperechoic bowel or dilated bowel loops in the five cases with available imaging data. Histopathology showed multi-visceral infiltrates with T lymphocytes and other cells, including eosinophils, the pancreas being affected in most of the cases (11/21) and as early as at 18 weeks of gestational age. Regarding the nine FOXP3 mutations found in these cases, six determine protein truncation and three predictably impair protein function. Having found distinct presentations for the same FOXP3 mutation in different families, we resorted to the mouse system and showed that the scurfy mutation also shows divergent severity of phenotype and age of death in C57BL/6 and BALB/c backgrounds. We also reviewed age-of-onset data from other monogenic Tregopathies leading to IPEX-like phenotypes. In monogenic IPEX-like syndromes, the intrauterine onset was only observed in two kindreds with IL2RB mutations, with two stillbirths and two premature neonates who did not survive. In conclusion, intrauterine IPEX cases seem to constitute a particular IPEX subgroup, certainly with the most severe clinical presentation, although no strict mutation-phenotype correlations could be drawn for these cases.