Complete DiGeorge Syndrome Research Articles

T-cells are significantly reduced in the luminal gastrointestinal tract of patients with “complete” 22q11.2 deletion syndrome (DiGeorge syndrome): Utilization of chromogenic multiplex immunohistochemistry to define cellular populations

Patients with 22q11.2 deletion syndrome or DiGeorge syndrome commonly report gastrointestinal symptoms in addition to more widely understood cardiac and immunodeficiency abnormalities. However, the morphologic features of gastrointestinal tract pathology in these patients are poorly understood. We previously reported that plasma cells are essentially absent from the luminal gastrointestinal tract of patients with “complete” DiGeorge syndrome. Herein, we add to the current understanding of the luminal gastrointestinal tract changes in patients with DiGeorge syndrome. Patients with cytogenetically confirmed DiGeorge syndrome were identified after approval from our institutional review board. Gastrointestinal tract biopsies from patients with DiGeorge syndrome that were severely immunosuppressed (complete DiGeorge syndrome, DGS-I), partially immunocompromised (partial DiGeorge syndrome, DGS), and from control patients were reviewed. Two panels of chromogenic multiplex immunohistochemistry (IHC) were performed to evaluate the immune cell infiltrate in the lamina propria of the duodenum and colon. “Panel #1” was composed of antibodies targeting CD3, CD20, and CD68. “Panel #2” was composed of antibodies targeting CD4, CD8, CD56, and TCRϒδ. Assessment of cell types identified by these antibody targets demonstrated a significant reduction of duodenal and colonic T-cells in patients with complete DiGeorge syndrome. In addition to establishing the morphologic phenotype of the luminal gastrointestinal tract of patients with DiGeorge syndrome, we also highlight our chosen technology of chromogenic multiplex IHC as a relatively accessible research and diagnostic tool with wide potential to be utilized across various disease processes.

Chronic norovirus infection in a pediatric patient with complete DiGeorge syndrome

Infectious gastroenteritis is a common acute illness that is usually self-limiting. Norovirus, in particular, is a common cause of acute gastroenteritis. In immunocompromised patients, however, norovirus infection may progress to prolonged viral shedding leading to debilitating and life-threatening consequences.A 3-year-old boy with congenital athymia and resulting severe T cell lymphopenia secondary to complete DiGeorge syndrome presented with acute worsening of chronic diarrhea. Previous work up for his chronic diarrhea included negative infectious and malabsorption studies. When he presented with acute worsening of diarrhea, work up included lymphocyte analysis that demonstrated stable severe T cell lymphopenia and infectious studies that were positive for norovirus. The patient had large volume diarrhea requiring hospital admission for intravenous fluids to manage dehydration and electrolyte derangements.Given the degree of immunocompromised and the risk for severe and chronic norovirus infection in this patient with complete DiGeorge syndrome, different therapeutic options were evaluated. The patient was started on oral immunoglobulin therapy 100 mg/kg three times per week as well as oral nitazoxanide 100 mg twice daily. Oral immunoglobulin therapy was discontinued after 2 months due to lack of perceived benefit. On days patient missed a dose of nitazoxanide, worsening of diarrhea was observed. Nitazoxanide therapy was continued given clear symptomatic benefit.While he experienced decreased number of bowel movements on nitazoxanide, his continued symptoms led to progressive weight loss, with a 12% decrease in body weight two months after norovirus diagnosis. Metronidazole was considered but was not initiated because concerns for side effects outweighed the evidence for benefit for this patient. Stool studies at this time demonstrated presence of fecal fat, consistent with malabsorption. The patient was subsequently started on total parental nutrition. His malabsorption and diarrhea persisted but he has been able to gain weight.This case demonstrates how severe norovirus infection can present in immunodeficient patients, specifically those with severe T cell lymphopenia. Moreover, this case highlights the need for research in therapeutics for the treatment of chronic norovirus infection in immunodeficient patients.

Timing of Immune Reconstitution in Patients With Congenital Athymia After Treatment With Allogeneic Processed Thymus Tissue-agdc

Congenital athymia is a rare pediatric condition characterized by the absence of a functioning thymus resulting in extremely low naïve T-cell numbers and severe immune deficiency. Allogeneic processed thymus tissue-agdc is approved for immune reconstitution in these patients. In clinical studies, naïve T-cell numbers increased from baseline through year 2 after allogeneic processed thymus tissue-agdc implantation. Based on these studies, immune reconstitution sufficient to overcome infection (>100 naïve CD4+ T cells/mm3) is unlikely to develop before 6–12 months after implantation and may take 2 years in some patients (Figure 1). This analysis aims to identify clinical features associated with delayed naïve T-cell development and impacts on clinical outcomes. In this post hoc analysis of data at year 1 (Y1) after allogeneic processed thymus tissue-agdc implantation, we evaluated clinical features of patients with < 100 naïve CD4+/mm3. Of 95 patients implanted in clinical trials, all 65 patients with baseline measurements had < 50 naïve CD4+/mm3. Of patients with Y1 measurements, 30/45 (66.7%) achieved >100 naïve CD4+/mm3 and 15/45 (33.3%) had < 100 naïve CD4+/mm3 (Tables 1, 2). Among patients with < 100 naïve CD4+/mm3 at Y1, 11/15 (73.3%) had atypical complete DiGeorge Syndrome (cDGS); all 11 atypical patients received glucocorticoids pre-implantation and calcineurin inhibitors pre- and post-implantation, and 6/11 received glucocorticoids post-implantation. Four of 15 patients (26.7%) with < 100 naïve CD4+/mm3 at Y1 had typical cDGS; 1 received calcineurin inhibitors pre- and post-implantation and 2 received glucocorticoids (pre-implantation only). Of 15 patients with < 100 naïve CD4+/mm3 at Y1, 10 (66.7%) experienced infection-related adverse events starting >1 year post-implantation. These events were reported for 8 atypical patients (all on pre-or post-implantation immunosuppressive therapy) and 2 typical patients (with no immunosuppressive therapy); most events resolved. At the time of last follow-up, 93.3% of patients (14/15) were alive; 1 patient died 7.6 years post-treatment (respiratory failure). In summary, most patients (66.7%) with available data achieved >100 naïve CD4+/mm3 by Y1 after allogeneic processed thymus tissue-agdc implantation. Amongst patients who did not, many had atypical cDGS and received immunosuppressive medications. No infection-related deaths were reported in patients with delayed naïve CD4+ T-cell reconstitution. [Display omitted] Table 1(abstract: 100) Characteristics of Patients With < 100 Naïve CD4+ T Cells/mm3 at Year 1 and Year 2 After ImplantationPatientAge at implantation, yearscDGS phenotypeGenetic backgroundaAlive at last follow-upInfection-related AE>1 year post-implantationImmunosuppression useCIPatients with <100 cells/mm3 at the year 1 visit10.8AtypicalHemizygous 22q11.2 deletion✓✓✓✓21.1AtypicalHemizygous 22q11.2 deletion✓No✓✓32.2AtypicalNo known mutation✓No✓✓40.7AtypicalCHARGE✓✓✓✓50.8AtypicalNo known mutation✓✓✓✓60.7AtypicalCHARGE✓✓✓✓71.3AtypicalCHARGE✓✓✓✓80.7TypicalHemizygous 22q11.2 deletion✓No✓✓92.3TypicalHemizygous 22q11.2 deletion✓NoNo✓10c0.2TypicalCHARGE✓✓NoNo110.4TypicalNo known mutationNod✓NoNoPatients with <100 cells/mm3 at the year 1 and year 2 visits121.4AtypicalHemizygous 22q11.2 deletion✓✓✓✓131.2AtypicalCHARGE✓No✓✓140.7AtypicalNo known mutation✓✓✓✓151.8AtypicalCHARGE✓✓✓✓Patients with <100 cells/mm3 at the year 2 visite160.3TypicalHemizygous 22q11.2 deletion✓✓NoNo170.9TypicalHemizygous 22q11.2 deletion✓✓NoNoAE, adverse event; cDGS, complete DiGeorge syndrome; CHARGE, coloboma, heart defect, choanal atresia, growth and developmental delay, genital hypoplasia, and ear anomalies or deafness syndrome; CHD7, chromodomain-helicase DNA-binding protein 7; CI, calcineurin inhibitor; EAS, efficacy analysis set; GC; glucocorticoids. Data based on EAS population (N = 95).aCHARGE includes CHD7mutation or other unknown CHARGE mutations.bIncludes methylprednisolone with anti-thymocyte globulin [rabbit] administered just before implantation.cPatient had renal impairment (defined as serum creatinine levels >0.4 mg/dL at baseline).dPatient died 7.6 years after allogeneic processed thymus tissue-agdc implantation (due to respiratory failure).eNaïve CD4+ T-cell data at the year 1 visit was not available for these patients.Table 2Naive CD4+ T cells/mm3 Over Time After Allogeneic Processed Thymus Tissue-agdc ImplantationaPatientNaïve CD4+ T cells/mm30.5–0.9 years1.0–1.4 years1.5–1.9 years≥2 yearsPatients with <100 cells/mm3 at the year 1 visit165.5NA48721046, 80NA2813101475NA4NA90, 521NA454511.9,51.0NA119.9, 219.3356.662.7,22.954.0NA218.5711,0NA7481250,100276NA9NA27NA10NA67.6359.9NA11NA47.9294.4NAPatients with <100 cells/mm3 at the year 1 and year 2 visits1246456454131068NA94.7, 149144,2339.934.466.4,1091518.534.072.939.9Patients with <100 cells/mm3 at the year 2 visitb1616273355173.9NA6967EAS, efficacy analysis set; NA, not available.Data based on EAS population (N = 95).aBased on available naïve CD4+ T-cell data.bNaïve CD4+ T-cell data at the year 1 visit was not available for these patients.

CD45RA+ Depleted Lymphocyte Infusion for Treatment of Refractory Cytomegalovirus Disease in Complete DiGeorge Syndrome: A Case Report

CD45RA+ Depleted Lymphocyte Infusion for Treatment of Refractory Cytomegalovirus Disease in Complete DiGeorge Syndrome: A Case Report

428: A PERSISTENT CASE OF COVID-19 IN A PATIENT WITH COMPLETE DIGEORGE SYNDROME

Introduction: DiGeorge Syndrome is a relatively common microdeletion syndrome defined by a deletion in chromosome 22 at position 22q11.2 and clinically characterized by T-cell deficiency, unique facial features, congenital heart disease and hypocalcemia. Complete DiGeorge Syndrome refers to a subset that is athymic (< 1%) without any T cell function. The adaptive immune response is then disturbed leading to an increased susceptibility to infections given the lack of cytotoxic response to infected cells. In this population, pathogens can persist and have unique presentations due to the lack of an adaptive immune response. Description: We present a case of persistent COVID-19 in a 3-year-old male with complete DiGeorge syndrome. Two months prior to presentation, he was treated with remdesivir for a symptomatic COVID-19 infection. He later represented with severe persistent hypocalcemia despite aggressive IV electrolyte repletion as well as a new acute hemolytic anemia with positive Coombs and concern for Graft vs Host disease. During his hospital course, he had worsening respiratory status leading to re-intubation. Bronchoscopy with BAL showed significant SARS-CoV-2 viral load and he was started on a repeat course of remdesivir and convalescent plasma. Two weeks after initial bronchoscopy, repeat BAL samples showed unchanged SARS-CoV-2 viral load leading to another course of remdesivir and convalescent plasma. After a month of invasive ventilation, he was able to be successfully extubated and eventually discharged from the hospital, despite having persistently an elevated SARS-CoV-2 viral load and polymerase chain reaction testing positivity. Discussion: This case illustrates a unique situation of COVID-19 in a patient without an adaptive immune response due to complete DiGeorge Syndrome. This patient population is athymic without any T cell function leading to a lack of cytotoxic response and a susceptibility to infections due to the inability to clear infected cells. With COVID’s high mutation rate leading to multiple new strains, we present a case illustrating the possibility of new strain mutations developing due to persistent COVID in a patient with an inability to clear the viral infection.

BALANCING GVHD IMMUNOSUPPRESSION AND COVID19 VIRAL REACTIVATION IN A PATIENT WITH ATYPICAL COMPLETE DIGEORGE SYNDROME

<h3>Introduction</h3> Complete DiGeorge syndrome (DGS) accounts for less than 1% of patients with DGS, with atypical DGS being even rarer. We present a patient with atypical complete DGS who developed autoimmune phenomena attributed to autologous GVHD, and subsequent prolonged respiratory failure due to COVID19 pneumonia while on immunosuppression. <h3>Case Description</h3> A 3-year old male infant of a diabetic mother with complete DGS awaiting thymic transplantation, hypoparathyroidism, hypogammaglobulinemia on IVIG, and recent asymptomatic COVID19 infection was admitted for AKI, electrolyte disarray secondary to malabsorption, and warm autoimmune hemolytic anemia. A month prior he had a persistent eczematous rash, chronic cough, recurrent diarrhea, and thinning hair. Labs revealed uptrending total IgE to 10,000 IU/ml, no eosinophilia, an oligoclonal population of gamma-delta T cells, and increased numbers of CD4+ and CD8+ lymphocytes, which were primarily CD45RO+ central memory T cells. A large portion were activated and expressed HLA-DR. Mitogen proliferation was normal. Given these findings, he was diagnosed with autologous GVHD secondary to autoreactive oligoclonal T cells, and subsequently, atypical complete DGS. Tacrolimus and methylprednisolone were started for immunosuppression. IgE and CD3+ T cells decreased on immunosuppression, but he developed hypoxemic respiratory failure with prolonged intubation due to COVID19 pneumonia. Immunosuppression was gradually weaned. IgE and CD3+ cells increased slightly, but he showed no clinical signs of GVHD and was discharged home after a 3.5 month hospital stay. <h3>Discussion</h3> This case highlights the difficult balance between immunosuppression and viral reactivation. After starting immunosuppression for treatment of GVHD, he developed severe COVID19 pneumonia.

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.

Clinical and Immunological Defects and Outcomes in Patients with Chromosome 22q11.2 Deletion Syndrome.

Chromosome 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans and can present with highly variable clinical manifestations. Immune deficiencies occur because of thymic hypoplasia or aplasia. This retrospective study included patients diagnosed with 22q11.2DS at a medical center between 2000 and 2021. We analyzed the association between clinical phenotypes, immunological abnormalities, age, and outcomes. Eighty-seven patients with 22q11.2DS had a median diagnostic age of 1.78months. Patients presented with congenital heart disease (CHD; 86.2%), major infections (75.9%), and failure to thrive (FTT; 58.6%). Autoimmunity, neuropsychiatric disorders, and hypoparathyroidism were significantly associated. Neonatal seizures were associated with early diagnosis before 2months (OR 8.56, 95% CI 1.21-60.58, P = 0.032). Immunological abnormalities included lymphopenia (93.1%), T lymphopenia (71.9%), CD4+ T lymphopenia (64.1%), a lack of hepatitis B vaccine antibodies (46.2%), and complete DiGeorge syndrome (cDGS) (2.3%). Severe lymphopenia and T lymphopenia improved at 3years of age. Two patients with cDGS were treated with hematopoietic stem cell transplantation, and one survived. The mortality rate was 12.8% and the estimated 35-year survival probability was 77.5%. Major infections experienced > four times were significantly associated with a decreased survival rate of 60%. Patients with CHD without FTT or recurrent infections had a better 20-year survival rate (96.2%). CHD, major infection, and FTT were common manifestations and poor prognostic factors. Autoimmunity, neuropsychiatric disorders, and hypoparathyroidism were significantly associated. Although T lymphopenia may improve with age, patients with 22q11.2DS require lifelong monitoring for immune dysregulation.

Relationship Between Severity of T cell Lymphopenia and Immune Dysregulation in Patients With DiGeorge Syndrome (22q11.2 Deletions and/or Related TBX1 Mutations): A USIDNET Study

To evaluate if the severity of T-cell lymphopenia is associated with immune dysregulation, such as autoimmunity and asthma, in patients with DiGeorge syndrome (DGS) and/or TBX1 mutation.In this study, researchers included 415 patients with DGS and/or TBX1 mutations from the US Immunodeficiency Network registry. Patients with complete and atypical complete DGS were excluded. The median age was 4.6 years (range: 0–45 years).This was a retrospective analysis of 415 patients with DGS and/or TBX1 mutations from the US Immunodeficiency Network registry. Patients were stratified on the basis of severity of initial absolute CD3+ T cells. The rate of infections, autoimmunity, and atopic disease were compared by using χ2 tests and multivariate logistic regression.In this DGS cohort, the median absolute CD3+ T-cell count was 1424 (range: 85–6371 cells/μl). Among the 415 DGS patients, 25% reported congenital heart disease, 4.1% reported autoimmunity, and 6.7% reported asthma. Absolute CD3 counts were lower in those with cardiac disease (P < .001). Patients with absolute CD3+ T cells <50% of age-adjusted normal values were more likely to have reported autoimmunity (odds ratio: 7.56; 95% confidence interval: 1.58 to 36.17; P = .01) and asthma (odds ratio: 4.5; 95% confidence interval: 1.06 to 18.93; P = .04) when compared with those with normal T cell counts. The most commonly reported autoimmune conditions were thyroid disease and cytopenias. Patients with reported autoimmunity more frequently had low CD19+ B cells (P = .002) and low immunoglobulin G (P = .005), when compared with those without autoimmunity. There was no association noted between low CD3+ T cells and immunoglobulin levels or infection rates.Patients with DGS and absolute CD3+ T cells <50% of age-adjusted normal levels had a higher odds of developing autoimmunity and/or asthma, when compared with those with normal T cell counts.Although it is well known that DGS increases the risk for autoimmunity and atopy, in this study, the authors investigated the association between the severity of T-cell lymphopenia and odds of autoimmunity and atopy. Patients with absolute CD3+ T cells <50% of age-adjusted normal levels had a significantly higher odds of developing autoimmunity and/or asthma. This information is useful to providers because it helps us identify those at higher risk for developing autoimmunity and/or asthma and allows us to heighten our surveillance in this population, especially because autoimmunity and/or asthma had increasing frequency with advancing age. This was a large study of DGS patients nationally; however, it was limited by the nature of registry data, which had variable areas of missing data.

M208 A RARE CONDITION IN A RARE DISEASE: A CHALLENGING CASE OF ATYPICAL COMPLETE DIGEORGE

DiGeorge Syndrome (DGS) is a congenital defect affecting the heart, thymus and parathyroid glands due to deletion of 22q11.2. This case describes an infant with Complete DiGeorge Syndrome who developed Atypical DiGeorge.

Plasma cells are essentially absent in the luminal gastrointestinal tract of patients with “complete” 22q11.2 deletion syndrome (DiGeorge syndrome)

Gastrointestinal symptoms are commonly reported in patients with 22q11.2 deletion syndrome or DiGeorge syndrome (DGS) in addition to the dominant cardiac manifestations and immunodeficiency. But literature providing specific morphologic details of the gastrointestinal tract pathology is very limited. Here, we provide the first comprehensive morphologic description of the luminal gastrointestinal tract changes in patients with DGS. Cytogenetically confirmed DGS patients were identified, clinical and laboratory data were reviewed to determine the severity of immunodeficiency, and patients were stratified into mildly immunocompromised, that is, partial DiGeorge anomaly or severely immunosuppressed, that is, complete DiGeorge anomaly groups. Gastrointestinal tract biopsies from these patients were retrospectively reviewed and compared with those from controls without the history of DGS. Patients with immunosuppressed DGS showed a near complete absence of plasma cells in the stomach, duodenum, and colon lamina propria by hematoxylin and eosin evaluation. Immunohistochemistry for CD138 used to highlight plasma cells confirmed this finding. The notable absence of plasma cells adds to the existing knowledge of the pathophysiology underlying DGSand expands the differential diagnostic considerations for this finding, which has been previously described in common variable immunodeficiency. It also provides a useful morphologic marker observable by the readily accessible light microscopy. Second, patients with DGS showed a mild increase in epithelial cell apoptosis in their colon. This finding is significant because of its overlap with morphologic features of gastrointestinal graft versus host disease as thymus transplantation is being used as a treatment option for patients with complete DGS.

Experience with cultured thymus tissue in 105 children

Currently, there are no approved therapies to treat congenital athymia, a condition of immune deficiency resulting in high early mortality due to infection and immune dysregulation. Multiple syndromic conditions, such as complete DiGeorge syndrome, 22q11.2 deletion syndrome, CHARGE (coloboma, heart defects, choanal atresia, growth or mental retardation, genital hypoplasia, and ear anomalies and/or deafness) syndrome, diabetic embryopathy, other genetic variants, and FOXN1 deficiency, are associated with congenital athymia. Our aims were to study 105 patients treated with cultured thymus tissue (CTT), and in this report, to focus on the outcomes of 95 patients with treatment-naive congenital athymia. A total of 10 prospective, single-arm open-label studies with patient enrollment from 1993 to 2020 form the basis of this data set. Patients were tested after administration of CTT for T-cell development; all adverse events and infections were recorded. A total of 105 patients were enrolled and received CTT (the full analysis set). Of those patients, 10 had diagnoses other than congenital athymia and/or received prior treatments. Of those 105 patients, 95 patients with treatment-naive congenital athymia were included in the efficacy analysis set (EAS). The Kaplan-Meier estimated survival rates at year 1 and year 2 after administration of CTT in the EAS were 77% (95% CI=0.670-0.844) and 76% (95% CI= 0.657-0.834), respectively. In all, 21 patients died in the first year before developing naive T cells and 1 died in the second year after receipt of CTT; 3 subsequent deaths were not related to immunodeficiency. Afew patients developed alopecia, autoimmune hepatitis, psoriasis, and psoriatic arthritis after year 1. The rates of infections, autologous graft-versus-host-disease manifestations, and autoimmune cytopenias all decreased approximately 1 year after administration of CTT. Treatment with CTT led to development of naive T cells with a 1-year survival rate of 77% and a median follow-up time of 7.6 years. Immune reconstitution sufficient to prevent infections and support survival typically develops 6 to12 months after administration of CTT.

Current and Future Therapeutic Approaches for Thymic Stromal Cell Defects.

Inborn errors of thymic stromal cell development and function lead to impaired T-cell development resulting in a susceptibility to opportunistic infections and autoimmunity. In their most severe form, congenital athymia, these disorders are life-threatening if left untreated. Athymia is rare and is typically associated with complete DiGeorge syndrome, which has multiple genetic and environmental etiologies. It is also found in rare cases of T-cell lymphopenia due to Nude SCID and Otofaciocervical Syndrome type 2, or in the context of genetically undefined defects. This group of disorders cannot be corrected by hematopoietic stem cell transplantation, but upon timely recognition as thymic defects, can successfully be treated by thymus transplantation using cultured postnatal thymic tissue with the generation of naïve T-cells showing a diverse repertoire. Mortality after this treatment usually occurs before immune reconstitution and is mainly associated with infections most often acquired pre-transplantation. In this review, we will discuss the current approaches to the diagnosis and management of thymic stromal cell defects, in particular those resulting in athymia. We will discuss the impact of the expanding implementation of newborn screening for T-cell lymphopenia, in combination with next generation sequencing, as well as the role of novel diagnostic tools distinguishing between hematopoietic and thymic stromal cell defects in facilitating the early consideration for thymus transplantation of an increasing number of patients and disorders. Immune reconstitution after the current treatment is usually incomplete with relatively common inflammatory and autoimmune complications, emphasizing the importance for improving strategies for thymus replacement therapy by optimizing the current use of postnatal thymus tissue and developing new approaches using engineered thymus tissue.

Inborn Error of Immunity or Atopic Dermatitis: When to be Concerned and How to Investigate

Around 20% of all children worldwide suffer from atopic dermatitis. Therefore, eczematous skin lesions and elevated serum immunoglobulin E (IgE) levels are common findings. Inborn errors of immunity (IEI) may be missed in the context of atopic dermatitis, and management and prognosis of these conditions can be substantially different. Children suffering from IEIs such as hyper-IgE syndromes, Wiskott-Aldrich syndrome, immunodysregulation polyendocrinopathy enteropathy X-linked syndrome, Omenn syndrome, the atypical complete DiGeorge syndrome, and skin barrier disorders like Comèl-Netherton syndrome and severe dermatitis-multiple allergies and metabolic wasting syndrome may present with additional red flags, which should raise a clinical suspicion for an underlying IEI. These red flags may include eczematous skin lesion manifesting prior to two months of life, disseminated or recurrent viral, bacterial, or fungal infections, mucocutaneous candidiasis, purpura, chronic diarrhea, or abnormalities in development or of connective tissue. A differential blood count, as well as a lymphocyte subset analysis, total immunoglobulin levels, and vaccination titers can help the clinician to decide whether a patient with eczematous skin lesions and elevated serum IgE should be referred to a clinical immunologist for a full immunological work-up and broad genetic analysis.

Replacing defective thymus function.

Transplantation of cultured postnatal allogeneic thymus has been successful for treating athymia, mostly associated with complete DiGeorge syndrome, for more than 20 years. Advances in molecular genetics provide opportunities for widening the range of athymic conditions that can be treated while advances in cell culture and organ/tissue regeneration may offer the prospect of alternative preparations of thymic tissue. There are potential broader applications of this treatment outside congenital athymia. At the same time as further characterization of the cultured thymus product in terms of thymic epithelial cells and lymphoid composition, preclinical studies have looked at de-novo generation of thymic epithelial cells from stem cells and explored scaffolds for delivering these as three-dimensional structures. In the era of newborn screening for T-cell lymphopaenia, a broadening range of defects leading to athymia is being recognized and new assays should allow differentiation of these from haematopoietic cell defects, pending their genetic/molecular characterization. Evidence suggests that the tolerogenic effect of transplanted thymus could be exploited to improve outcomes after solid organ transplantation. Thymus transplantation, the accepted standard treatment for complete DiGeorge syndrome is also appropriate for other genetic defects leading to athymia. Improved strategies for generating thymus may lead to better outcomes and broader application of this treatment.

Predicting Autoimmunity Development in 22q11.2DS

Autoimmunity is a known complication of the 22q11.2 deletion syndrome (22q11.2DS) but predictive biomarkers for risk have not been identified. In most cases, autoimmunity develops 8 years after 22q11.2DS diagnosis. We sought to determine if immune biomarkers during early childhood could predict autoimmunity later in life. Retrospective chart investigation of patients with 22q11.2 from Duke University from 2008 to 2019. Only participants who had 22q11.2 deletion by FISH or microarray were evaluated. Fisher & Mann Whitney U tests were used for statistical analysis comparing 22q11.2DS patients with and without autoimmune disease. Study was IRB approved. Seventy-one patients with 22q11.2DS were identified, and 19 of 71 (26.8%) had a physician diagnosis of autoimmune disease. The most common autoimmune diagnoses were cytopenias followed by psoriasis and juvenile arthritis. Prevalence of an autoimmune diagnosis was not significantly different for those with complete versus partial DiGeorge Syndrome. The presence of hypoparathyroidism (OR 3.5, p=0.03) and allergic rhinitis (OR 0.3, p=0.03) significantly correlated with autoimmunity. T cell lymphopenia at 22q11.2 diagnosis (median age 4 years) was correlated with autoimmunity (p=0.01). Multiple T cell subsets were independently associated with autoimmunity including CD4 (p=0.01), CD8 (p=0.01), and naïve CD4 T cells (p=0.01). NK cell numbers, B cell numbers, PHA response, vaccine responses, and size of 22q11.2 deletion were not correlative with autoimmunity. 22q11.2DS patients with hypoparathyroidism and T cell lymphopenia were associated with a higher risk of autoimmune disease. This study indicates that immune biomarkers present in early childhood may predict risk for autoimmunity later in life.

ESGCT 27th Annual Congress In collaboration with SETGyc Barcelona, Spain October 22–25, 2019 Abstracts

Xenotransplantation of transgenic porcine pancreatic islets offers a promising alternative source to circumvent current limitations posed by the scarcity of allogeneic donors. We have investigated the feasibility to generate tissue engineered SLA silenced islet cell clusters (ICC) to decrease xenogeneic immune responses Pancreatic islets single cell suspensions were generated by enzymatic digestion of porcine ICCs. Single cells were silenced for SLA expression by lentiviral vectors encoding for Nanoluciferase as reporter gene and for short hairpin RNAs targeting beta2-microglobulin or class II transactivator, respectively. SLA transcripts were evaluated by real-time PCR and protein levels by flow cytometry and fluorescence microscopy analyses. The effect of SLA silencing was evaluated in human T and NK cell cytotoxicity assays. SLA-silenced pancreatic beta-cells were then reassembled into ICCs in stirred bioreactors. SLA class I silencing reached a level of up to 84% and class II by up to 50% on pancreatic islet cell. Silencing SLA expression did not affect cell viability and the insulin-producing beta-cell phenotype. Xenogeneic T-cell immune responses (p < 0.05) as well as antibody-mediated cellular-dependent immune responses (p < 0.01) were significantly decreased. Silencing SLA class I expression did not increase susceptibility to NK-cell cytotoxicity. In stirred bioreactors, tissue engineered islets showing the typical 3D-structure and morphology of ICC were assembled from SLA-silenced pancreatic cell suspensions. These data shows the feasibility to generate low immunogenic porcine ICC from transgenic pigs after single cell engineering and post-transduction islet reassembling that might serve as a robust alternative to allogeneic pancreatic islet cell transplantation.

De novo generation of a functional human thymus from induced pluripotent stem cells

A proper functional thymus is required for generation of T cell–mediated immunity. This is dramatically illustrated by patients lacking a thymus, such as children with complete DiGeorge syndrome, which is fatal if left untreated.1-3 Therapeutic options for such patients are limited and confined to transplantation of small fragments from allogeneic neonatal thymi.

Newborn Screening for Severe Combined Immunodeficiency and T-cell Lymphopenia in California, 2010-2017.

Newborn screening for severe combined immunodeficiency (SCID) was instituted in California in 2010. In the ensuing 6.5 years, 3 252 156 infants in the state had DNA from dried blood spots assayed for T-cell receptor excision circles (TRECs). Abnormal TREC results were followed-up with liquid blood testing for T-cell abnormalities. We report the performance of the SCID screening program and the outcomes of infants who were identified. Data that were reviewed and analyzed included demographics, nursery summaries, TREC and lymphocyte flow-cytometry values, and available follow-up, including clinical and genetic diagnoses, treatments, and outcomes. Infants with clinically significant T-cell lymphopenia (TCL) were successfully identified at a rate of 1 in 15 300 births. Of these, 50 cases of SCID, or 1 in 65 000 births (95% confidence interval 1 in 51 000-1 in 90 000) were found. Prompt treatment led to 94% survival. Infants with non-SCID TCL were also identified, diagnosed and managed, including 4 with complete DiGeorge syndrome who received thymus transplants. Although no cases of typical SCID are known to have been missed, 2 infants with delayed-onset leaky SCID had normal neonatal TREC screens but came to clinical attention at 7 and 23 months of age. Population-based TREC testing, although unable to detect immune defects in which T cells are present at birth, is effective for identifying SCID and clinically important TCL with high sensitivity and specificity. The experience in California supports the rapid, widespread adoption of SCID newborn screening.

DIAGNOSIS AND MANAGEMENT OF AN INFANT WITH ATYPICAL COMPLETE DIGEORGE IMMUNOLOGIC PHENOTYPE

Introduction The diagnosis of complete DiGeorge syndrome is seen ≤1.5% of patients with 22q11.2 syndrome. We present a rare case of an infant with CHARGE syndrome with atypical complete DiGeorge immunologic phenotype. Case Description A 3-day old Caucasian male was referred for absent TRECs for SCID. He had known arch hypoplasia prior to delivery. Following delivery, a tracheoesophageal fistula was identified. Additional congenital anomalies included large patent ductus arteriosus, bilateral iris colobomas, dysplastic ears, microphallus, cryptorchidism, and bilateral hydronephrosis. His initial lymphocyte enumeration demonstrated absent T-cells, normal number of B-cells and NK-cells. Lymphocyte proliferation to mitogens was absent. Targeted sequencing demonstrated a new variant in CHD7c.2698-11A>G predicted to affect splicing. SCID genetic panel and chromosomal microarray were normal. Based on workups and congenital anomalies, he was diagnosed with CHARGE syndrome with a complete DiGeorge phenotype. At 5 months of age, he developed Omenn syndrome-like manifestations with diffuse non-blanching erythematous macular rash over his body. Serial lymphocyte subsets demonstrated the development of T-cells expressing HLA-DR indicating the emergence of activated T-cells (CD3 269/cumm; CD3+HLA-DR 258/cumm, 96% of total T-cells). Spectratyping confirmed the presence of oligoclonal-T-cells. Therefore, immunosuppression with cyclosporin and prednisolone was given for treatment of self-reactive oligoclonal-T-cells with resolution of rashes. He is currently awaiting thymus transplantation, and receiving IVIG, and antimicrobial prophylaxis. Discussion Although not yet approved by FDA, thymus transplantation is the preferred treatment for complete DiGeorge syndrome. Additionally, close monitoring of activated self-reactive oligoclonal-T-cells symptoms with proper immunosuppressive treatment is crucial while patient is waiting for thymus transplantation.