Learning the Autoimmune Pathogenesis Through the Study of Aire.

One of the difficulties in studying the pathogenesis of autoimmune diseases is that the disease is multifactorial involving sex, age, MHC, environment, and some genetic factors. Because deficiency of Aire, a transcriptional regulator, is an autoimmune disease caused by a single gene abnormality, Aire is an ideal research target for approaching the enigma of autoimmunity, e.g., the mechanisms underlying Aire deficiency can be studied using genetically modified animals. Nevertheless, the exact mechanisms of the breakdown of self-tolerance due to Aire's dysfunction have not yet been fully clarified. This is due, at least in part, to the lack of information on the exact target genes controlled by Aire. State-of-the-art research infrastructures such as single-cell analysis are now in place to elucidate the essential function of Aire. The knowledge gained through the study of Aire-mediated tolerance should help our understanding of the pathogenesis of autoimmune disease in general.

Novel Insights into the Autoimmunity from the Genetic Approach of the Human Disease.

Autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic inborn error of autoimmunity that is caused by damaging germline variants in the AIRE gene and clinically manifests with multiple autoimmune diseases in patients. Studies on the function of the AIRE gene, discovered in 1997, have contributed to fundamental aspects of human immunology as they have been important in understanding the basic mechanism of immune balance between self and non-self. This chapter looks back to the discovery of the AIRE gene, reviews its main properties, and discusses the key findings of its function in the thymus. However, more recent autoantibody profilings in APECED patients have highlighted a gap in our knowledge of the disease pathology and point to the need to revisit the current paradigm of AIRE function. The chapter reviews these new findings in APECED patients, which potentially trigger new thoughts on the mechanism of immune tolerance.

Identification of AIRE pathogenic variants ends diagnostic odyssey for Saudi child with infantile-onset keratoconjunctivitis as an early sign of autoimmune polyglandular syndrome type1; a case report.

PURPOSE: Chronic keratoconjunctivitis is a rare presentation of autoimmune polyglandular syndrome type 1 (APS-1) during the first year of life. Herein, We report a case of a 10-month-old baby girl with chronic bilateral keratoconjunctivitis, corneal scarring and neovascularization that was treated initially with topical immunosuppressants. METHODS: Detailed ophthalmological assessment followed by molecular testing using whole exome sequencing. RESULTS: In addition to the severe chronic bilateral keratoconjunctivitis, corneal scarring and neovascularization, patient weight was found to be low than 10th percentile. Further genetic testing revealed autoimmune regulator (AIRE) gene variant that was only reported once in the literature confirming the diagnosis of APS-1. Further workup detected hypoparathyroidism that was treated with calcium supplementation. CONCLUSION: Our case represents the importance of multidisciplinary services and highlights the role of genetic testing in diagnosing such syndromic cases. We reviewed previous reports and found that available treatment for ocular involvement is usually nonsatisfactory; however, early detection and referral by ophthalmologists could result in treating previously undetected endocrine disorders that can be life threatening if left untreated.

A novel missense mutation in the AIRE gene underlying autoimmune polyglandular syndrome type 1.

The immune regulator gene AIRE plays an essential role in the establishment of immune tolerance and the prevention of autoimmunity. This transcription factor plays a critical role in promoting self-tolerance in the thymus by regulating the expression of a large number of self-antigens that share the common feature of being tissue-restricted in their expression pattern in the periphery. Dysfunction of AIRE in humans causes a rare disease, autoimmune polyglandular syndrome type 1 (APS1), characterized by an autoimmune response against peripheral tissues, particularly endocrine tissues. Although a few dominant mutations have been described, the inactivation of AIRE is usually caused by recessive mutations. Recent data suggests that alterations in AIRE function contribute not only to APS1 but also to more common forms of autoimmune disease. Here, we present a previously unreported missense mutation (NM_000383.2:c.260 T > C) in exon 2 of the AIRE gene, predicted to cause the substitution (p.(Leu87Pro)) in the CARD domain of the AIRE protein. When inherited in conjunction with another dysfunctional AIRE allele, this mutation was associated with immune dysregulation in a pediatric patient. The presence of hypergammaglobulinemia, malabsorption syndrome, ectodermal dysplasia, mucocutaneous candidiasis, vitiligo, and hypothyroidism as well as the presence of multiple autoantibodies allowed us to confirm an APS1 diagnosis.

Identification of unstable regulatory and autoreactive effector T cells that are expanded in patients with FOXP3 mutations.

Studies of the monogenic autoimmune disease immunodysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX) have elucidated the essential function of the transcription factor FOXP3 and thymic-derived regulatory T cells (Tregs) in controlling peripheral tolerance. However, the presence and the source of autoreactive T cells in IPEX remain undetermined. Here, we investigated how FOXP3 deficiency affects the T cell receptor (TCR) repertoire and Treg stability in vivo and compared T cell abnormalities in patients with IPEX with those in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED). To study Tregs independently of their phenotype and to analyze T cell autoreactivity, we combined Treg-specific demethylation region analyses, single-cell multiomic profiling, and bulk TCR sequencing. We found that patients with IPEX, unlike patients with APECED, have expanded autoreactive T cells originating from both autoreactive effector T cells (Teffs) and Tregs. In addition, a fraction of the expanded Tregs from patients with IPEX lost their phenotypic and functional markers, including CD25 and FOXP3. Functional experiments with CRISPR-Cas9-mediated FOXP3 knockout Tregs and Tregs from patients with IPEX indicated that the patients' Tregs gain a TH2-skewed Teff-like function, which is consistent with immune dysregulation observed in these patients. Analyses of FOXP3 mutation-carrier mothers and a patient with IPEX after hematopoietic stem cell transplantation indicated that Tregs expressing nonmutated FOXP3 prevent the accumulation of autoreactive Teffs and unstable Tregs. These findings could be directly used for diagnostic and prognostic purposes and for monitoring the effects of immunomodulatory treatments.

[Autoimmune polyendocrine syndrome in adults. Focus on rheumatological aspects of the problem: A review].

Autoimmune polyglandular syndromes (APS) are a heterogeneous group of clinical conditions characterized by functional impairment of multiple endocrine glands due to loss of central or peripheral immune tolerance. These syndromes are also often accompanied by autoimmune damage to non-endocrine organs. Taking into account the wide range of components and variants of the disease, APS is usually divided into a rare juvenile type (APS 1) and a more common adult type (APS 2-4). APS type 1 is caused by a monogenic mutation, while APS types 2-4 have a polygenic mode of inheritance. One subtype of adult APS (APS 3D) is characterized by a combination of autoimmune thyroid disease and autoimmune rheumatic disease. This review considers the available literature data on combinations that meet the above criteria. Many studies have noted a significantly higher prevalence of rheumatic diseases in patients with autoimmune thyroid disease compared with the control group. Also, as in a number of rheumatic diseases, a more frequent occurrence of autoimmune thyroiditis, primary hypothyroidism and Graves' disease was noted.

Ruxolitinib Rescues Multiorgan Clinical Autoimmunity in Patients with APS-1.

Autoimmune polyendocrine syndrome type-1 (APS-1) is caused by mono- or biallelic loss-of-function variants of the autoimmune regulator gene AIRE underlying early-onset multiorgan autoimmunity and the production of neutralizing autoantibodies against cytokines, accounting for mucosal candidiasis and viral diseases. Medical intervention is essential to prevent or attenuate autoimmune manifestations. Ruxolitinib is a JAK inhibitor approved for use in several autoimmune conditions. It is also used off-label to treat autoimmune manifestations of a growing range of inborn errors of immunity. We treated three APS-1 patients with ruxolitinib and followed them for at least 30 months. Tolerance was excellent, with no medical or biological adverse events. All three patients had remarkably positive responses to ruxolitinib for alopecia, nail dystrophy, keratitis, mucosal candidiasis, steroid-dependent autoimmune hepatitis, exocrine pancreatic insufficiency, renal potassium wasting, hypoparathyroidism, and diabetes insipidus. JAK inhibitors were therefore considered an effective treatment in three patients with APS-1. Our observations suggest that JAK/STAT pathways are involved in the pathogenesis of APS-1 autoimmune manifestations. They also suggest that JAK inhibitors should be tested in a broader range of APS-1 patients.

A partial form of AIRE deficiency underlies a mild form of autoimmune polyendocrine syndrome type 1.

Autoimmune polyendocrine syndrome type 1 (APS-1) is caused by mutations in the autoimmune regulator (AIRE) gene. Most patients present with severe chronic mucocutaneous candidiasis and organ-specific autoimmunity from early childhood, but the clinical picture is highly variable. AIRE is crucial for negative selection of T cells, and scrutiny of different patient mutations has previously highlighted many of its molecular mechanisms. In patients with a milder adult-onset phenotype sharing a mutation in the canonical donor splice site of intron 7 (c.879+1G>A), both the predicted altered splicing pattern with loss of exon 7 (AireEx7-/-) and normal full-length AIRE mRNA were found, indicating leaky rather than abolished mRNA splicing. Analysis of a corresponding mouse model demonstrated that the AireEx7-/- mutant had dramatically impaired transcriptional capacity of tissue-specific antigens in medullary thymic epithelial cells but still retained some ability to induce gene expression compared with the complete loss-of-function AireC313X-/- mutant. Our data illustrate an association between AIRE activity and the severity of autoimmune disease, with implications for more common autoimmune diseases associated with AIRE variants, such as primary adrenal insufficiency, pernicious anemia, type 1 diabetes, and rheumatoid arthritis.

Leber congenital amaurosis as the initial and essential manifestation in a Chinese patient with autoimmune polyglandular syndrome Type 1.

PURPOSE: Autoimmune polyglandular syndrome Type 1 (APS-1) is a rare autosomal recessive disorder caused by defects in the autoimmune regulator (AIRE) gene. Patients are generally diagnosed at ages between five and fifteen years when they exhibit three or more manifestations, most typically mucocutaneous candidiasis, autoimmune Addison's disease, and hypoparathyroidism. Our study aims to report the first case of a Chinese APS-1 patient, presented with LCA as the initial and essential clinical feature of this rare syndrome. METHODS: Detailed medical and family history were recorded for the patient. Also, the comprehensive ophthalmological examinations were conducted. Whole exome sequencing (WES) was applied to screen pathogenic variants. Sanger sequencing validation and segregation analysis were further performed for confirmation. RESULTS: A 3-year-old boy with severely impaired vision and initially referred as LCA. However, with a detailed history review, oral candidiasis, dental enamel hypoplasia, and nail candida infection were revealed. Moreover, genetic analysis revealed the homozygous c.769C>T (p.R257X) in AIRE gene (NM_000383.3) as the causative variant. CONCLUSION: We presented one case diagnosed with APS-1 based on clinical characteristics and genetic analysis. Our study demonstrated that LCA could serve as a warning sign for APS-1 and a potential trigger of early screening, which might prevent life-threatening complications.

Analysis of a series of Italian APECED patients with autoimmune hepatitis and gastro-enteropathies.

Introduction: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome is a rare monogenic disease determined by biallelic mutations in AIRE gene, which encodes a transcription factor essential for central immune tolerance. Classic diagnosis is determined by the presence of two of the main APECED clinical diseases: chronic mucocutaneous candidiasis, chronic hypoparathyroidism, and Addison's disease. Non-endocrine autoimmunity, involving the liver, intestine, eyes, and kidneys, is generally reported in a minority of European patients, while American APECED patients have a higher tendency of developing organ-specific non-endocrine manifestations early in life. This observation led to the revision of the diagnostic criteria to permit earlier diagnosis based on the appearance of one classic triad symptom or one non-classical manifestation at a young age in the presence of IFNωAbs or AIRE mutations (Ferre-Lionakis criteria). Patients and methods: We analyzed the clinical, genetic, and autoantibody (Ab) profiles in a series of 14 pediatric Italian APECED patients with gastrointestinal manifestations (seven male and seven female patients). Ten patients presented hepatitis (APECED-associated hepatitis (APAH)), while seven were affected by constipation, diarrhea, and malabsorption. Four patients had developed APAH before classic triad symptoms. Results: Based on the age of appearance of non-endocrine manifestations including APAH and gastro-enteropathy, the Ferre-Lionakis criteria would have allowed an expedited diagnosis in 11/14 patients. Abs to tryptophan hydroxylase (TPHAb) and hepatic aromatic l-amino acid decarboxylase (AADC) were significantly associated with APECED patients of the present series. Abs to cP4501A2 were detectable in the serum of 4/8 patients with APAH, and Abs to cP4502A6 were detectable in 3/8 patients. AADC Abs tested positive in 5/7 patients, which is indicative of gastrointestinal dysfunction in APECED and TPHAb in 5/7 patients with gastrointestinal dysfunction. IFNAb was significantly associated with the syndrome. Conclusion: Although Ferre-Lionakis expanded criteria applied to the American cohorts of APECED patients would require validation in independent large cohorts of European patients, the results of this study emphasize the importance to evaluate the presence and the age of appearance of APAH and autoimmune enteropathy even in European cohorts for an earlier APECED diagnosis. An earlier APECED diagnosis would also allow the prevention of episodes of life-threatening hypocalcemic seizures and adrenal crisis, which are the main manifestations of undiagnosed APECED.

Ocular features of autoimmune polyendocrinopathy candidiasis ectodermal dystrophy.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a multisystemic rare genetic disorder characterised by abnormalities of the immune system. We report the ocular features of APECED in two siblings of an Indian family, out of four who are still living. The ocular features of this disorder primarily included madarosis, refractive error, heterochromia, corneal opacity and peripheral retinal pigment epithelium degeneration. There is marked phenotypical heterogeneity in this disorder. We found differences even between monozygotic twins. While one of the twins did not have any ocular issues, the other one did. The child with corneal involvement was the most symptomatic; however, it did not lead to visual impairment. On genetic workup, homozygous p.M1V mutation was found in exon 1 of AIRE gene that has not been studied in Indian subjects with APECED. To the best of our knowledge, there is no report in literature describing ocular features of APECED in an Indian family with distinctive genetic involvement.

Autoimmune regulator (Aire) deficiency results in reduced memory CD8+ T cells after Listeria monocytogenes infection in a murine model.

Homozygous mutations in the autoimmune regulator (AIRE) gene that cripple thymic negative selection of autoreactive T cells result in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). However, how AIRE regulates the T-cell response against foreign pathogens is not well understood. Here, we observed comparable primary CD8+ T cells but a markedly reduced memory T-cell population and protective function in Aire-/- mice compared with wild-type after infection with a strain of recombinant Listeria monocytogenes. In adoptive transfer models, exogenous congenic CD8+ T cells transferred into Aire-/- mice also showed a reduction in the memory T-cell population, indicating an important role for extrathymic Aire-expressing cells in shaping or sustaining memory T cells. Moreover, using a bone marrow chimeric model, we found that Aire expressed in radioresistant cells plays an important role in maintaining the memory phenotype. These results provide important insights into the role of extrathymic Aire in the T-cell response to infection.

Systemic interferon type I and B cell responses are impaired in autoimmune polyendocrine syndrome type 1.

Autoimmune polyendocrine syndrome type I (APS-1) is caused by mutations in the autoimmune regulator (AIRE) gene and characterised clinically by multiple autoimmune manifestations and serologically by autoantibodies against tissue proteins and cytokines. We here hypothesised that lack of AIRE expression in thymus affects blood immune cells and performed whole-blood microarray analysis (N = 16 APS-I patients vs 16 controls), qPCR verification, and bioinformatic deconvolution of cell subsets. We identified B cell responses as being downregulated in APS-1 patients, which was confirmed by qPCR; these results call for further studies on B cells in this disorder. The type I interferon (IFN-I) pathway was also downregulated in APS-1, and the presence of IFN antibodies is the likely reason for this mild overall downregulation of the IFN-I genes in most APS-1 patients.

Bone Tissue Evaluation Indicates Abnormal Mineralization in Patients with Autoimmune Polyendocrine Syndrome Type I: Report on Three Cases.

Autoimmune polyendocrine syndrome type-1 (APS1) is characterized by autoimmune manifestations affecting different organs from early childhood on. Immunological abnormalities, the resulting endocrinopathies, and their treatments may compromise bone health. For the first time in APS1, we analyzed transiliac bone biopsy samples by bone histomorphometry and quantitative backscattered electron imaging in three adult patients (female P1, 38 years; male P2, 47 years; male P3, 25 years). All had biallelic mutations in the autoimmune regulator gene and in addition to endocrinopathies, also significant bone fragility. Histomorphometry showed bone volume in the lower normal range for P1 (BV/TV, - 0.98 SD) and P3 (- 1.34 SD), mainly due to reduced trabecular thickness (TbTh, - 3.63 and - 2.87 SD). In P1, osteoid surface was low (OS/BS, - 0.96 SD); active osteoblasts and double labeling were seen only on cortical bone. P3 showed a largely increased bone turnover rate (BFR/BV, + 4.53 SD) and increased mineralization lag time (Mlt, + 3.40 SD). Increased osteoid surface (OS/BS, + 2.03 and + 4.71 SD for P2 and P3) together with a large proportion of lowly mineralized bone area (Trab CaLow, + 2.22 and + 9.81 SD for P2 and P3) and focal mineralization defects were consistent with abnormal mineralization. In all patients, the density and area of osteocyte lacunae in cortical and trabecular bone were similar to healthy adults. The bone tissue characteristics were variable and included decreased trabecular thickness, increased amount of osteoid, and abnormal mineralization which are likely to contribute to bone fragility in patients with APS1.

Autoimmune regulator (AIRE): Takes a hypoxia-inducing factor 1A (HIF1A) route to regulate FOXP3 expression in PCOS.

PROBLEM: Autoimmune polyendocrinopathy-candidiasis- ectodermal dystrophy (APECED) pathology due to autoimmune regulator (AIRE) gene mutations leads to loss of central tolerance triggering immune attack, a factor causing infertility. One of the targets of autoimmune attack is ovary and its repercussion results in polycystic ovarian syndrome (PCOS). Although reduced Tregs have been reported in PCOS, a lacunae exists on the status of AIRE gene expression and its role in treg insufficiency via HIF1A-FOXP3 axis in PCOS. METHOD OF STUDY: This is a case-control cohort study recruiting 40 normal and 40 PCOS volunteers for peripheral blood sample collection and PCOS diagnoses were based on Rotterdam Consensus criteria. AIRE and HIF1A expression status was analysed by qRT PCR and western blot. FACS analyses was conducted on AIRE silenced peripheral blood mononuclear cells (PBMCs) after Treg induction. RESULTS: Our results indicate a reduced AIRE (fold change log2 (RQ) = -2.6, P < .01) and increased HIF1A (fold change log2 (RQ) = 3.6, P < .02) in PBMCs of PCOS subjects compared to age-matched controls. Western blot of AIRE and HIF1A corroborates with qRT PCR data. Our CHIP data demonstrate AIRE mediated HIF1A promoter regulation. Silencing of AIRE in PBMCs contributes to the upregulation of HIF1A transcripts by two-fold (P < .0015) and downregulation in FOXP3 expression by three-fold (P < .0017). FACS analyses revealed that silencing of AIRE reduces Tcell to Treg conversion. CONCLUSIONS: Our consolidated results derive a new connection among AIRE-HIF1A-FOXP3 with AIRE reduction enabling increased HIF1A resulting in reduced FOXP3 in PBMCs of PCOS patients leading to Treg insufficiency.

A non-classical presentation of APECED in a family with heterozygous R203X AIRE gene mutation.

PURPOSE: Biallelic loss-of-function mutations of AIRE cause the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome. However, single nucleotide mutations may cause a milder phenotype. In this paper, we describe an unusual and mild phenotype in a mother and her two children (son and daughter) who carry a rare heterozygous mutation of AIRE. METHODS AND RESULTS: The son presented with alopecia and subclinical hypothyroidism due to Hashimoto's Thyroiditis (HT); the daughter had alopecia, vaginal mycosis, stomach pains and subclinical hypothyroidism due to HT; and the mother had alopecia, vaginal mycosis and stomach pains. Organ- and non-organ-specific autoantibodies were evaluated as well as antibodies against interleukin-17A, -17F, -22 (IL-Abs) and interferon -α and -ω (IFN-Abs). The organ- and non-organ-specific autoantibodies screening was negative in the son, while the daughter was positive for liver-kidney microsomal antibodies (LKMAbs) and the mother was positive for glutamic acid decarboxylase antibodies (GADAbs). Daughter and mother were also positive for IFN-Abs. Analysis of the AIRE gene identified a rare heterozygous R203X mutation in all three family members. CONCLUSIONS: We describe for a first time a family with heterozygous R203X AIRE mutation causing an APECED-like condition, as confirmed by presence of IFN-Abs. The unusual mild phenotype should be reassuring for the patients and assist in their clinical management.

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.

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.

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.

Multiple endocrine neoplasia type 2 and autoimmune polyendocrine syndromes (type 1 diabetes mellitus and Graves' disease) in a 16-year-old male with Kabuki syndrome.

Multiple endocrine neoplasia type 2A (MEN2A) is caused by germline pathogenic variants in the RET proto-oncogene and is characterized by medullary thyroid cancer (MTC), pheochromocytoma, and hyperparathyroidism. Autoimmune polyendocrine syndromes (APS) are defined as multiple endocrine gland insufficiency associated with loss of immune tolerance. APS type 2 (APS-2) consists of at least two of the following diseases: type 1 diabetes mellitus (T1DM), autoimmune thyroid disease, and Addison's disease. We describe the clinical, molecular, and biochemical findings of MEN2A, APS-2, and Kabuki syndrome (KS) in a 16-year-old male. Whole exome sequencing was performed to identify the genetic cause of the pheochromocytoma and syndromic features including facial dysmorphism, developmental delay, and epilepsy. RET pathogenic variant and KMT2D pathogenic variant were identified, and he was diagnosed with MEN2A and KS. This is the first case of association between MEN2 and APS in adolescence and the second proven case in humans. In addition, this is the first report of MEN2 and APS in KS.