Down Syndrome in Children: A Primary Immunodeficiency with Immune Dysregulation.

Background: The multisystemic features of Down syndrome (DS) in children are accompanied by immunodeficiency, making them susceptible to infections and immune dysregulation with autoimmune, allergic, inflammatory, and hematological complications. This study was aimed at a better understanding of the abnormalities within the B and T cell compartments and their correlations with clinical immunophenotypes. Methods: Medical records of 35 DS children were retrospectively reviewed, referring to clinical symptomatology including history of infections, immune dysregulation disorders, and humoral and cellular immune response. Results: While the etiology of respiratory tract infections included typical viral and bacterial pathogens, SARS-CoV2-induced inflammatory disease and syndromic immunodeficiency contributed significantly to the deterioration of the clinical course. Allergic diseases in the form of asthma, allergic rhinitis, and alimentary allergy were the most frequent manifestations of immune dysregulation and were followed by autoimmune disorders, such as Crohn's disease, celiac disease, autoimmune thyroiditis, and alopecia, as well as inflammatory disorders, balanitis xerotica obliterans and lymphadenopathy, and a hematological disorder of myelopoiesis. Deficiency of serum immunoglobulin levels, reduced numbers of naïve B cells, and non-switched memory B cells along with low naïve T helper cells and significantly reduced regulatory T helper cells were the most prominent immune abnormalities. Conclusions: The loss of naïveté in B and T lymphocyte compartments with a deficiency of regulatory T cells may be underpinning pathomechanisms for the skewed immune response. The clinical immunophenotype in DS is complex and represents syndromic primary immunodeficiency with immune dysregulation.

Immunogenetic Landscape in Pediatric Common Variable Immunodeficiency.

Common variable immunodeficiency (CVID) is the most common symptomatic antibody deficiency, characterized by heterogeneous genetic, immunological, and clinical phenotypes. It is no longer conceived as a sole disease but as an umbrella diagnosis comprising a spectrum of clinical conditions, with defects in antibody biosynthesis as their common denominator and complex pathways determining B and T cell developmental impairments due to genetic defects of many receptors and ligands, activating and co-stimulatory molecules, and intracellular signaling molecules. Consequently, these genetic variants may affect crucial immunological processes of antigen presentation, antibody class switch recombination, antibody affinity maturation, and somatic hypermutation. While infections are the most common features of pediatric CVID, variants in genes linked to antibody production defects play a role in pathomechanisms of immune dysregulation with autoimmunity, allergy, and lymphoproliferation reflecting the diversity of the immunogenetic underpinnings of CVID. Herein, we have reviewed the aspects of genetics in CVID, including the monogenic, digenic, and polygenic models of inheritance exemplified by a spectrum of genes relevant to CVID pathophysiology. We have also briefly discussed the epigenetic mechanisms associated with micro RNA, DNA methylation, chromatin reorganization, and histone protein modification processes as background for CVID development.

The clinical phenotype with gastrostomy and abdominal wall infection in a pediatric patient with Takenouchi-Kosaki syndrome due to a heterozygous c.191A > G (p.Tyr64Cys) variant in CDC42: a case report.

The CDC42 (cell division cycle homolog 42) gene product, Cdc42 belongs to the Rho GTPase family which plays a pivotal role in the regulation of multiple cellular functions, including cell cycle progression, motility, migration, proliferation, transcription activation, and reactive oxygen species production. The Cdc42 molecule controls various tissue-specific functional pathways underpinning organogenesis as well as developmental integration of the hematopoietic and immune systems. Heterozygous c.191A>G (p.Tyr64Cys) pathogenic variants in CDC42 cause Takenouchi-Kosaki syndrome characterized by a spectrum of phenotypic features comprising psychomotor developmental delay, sensorineural hearing loss, growth retardation, facial dysmorphism, cardiovascular and urinary tract malformations, camptodactyly, accompanied by thrombocytopenia and immunodeficiency of variable degree. Herein, we report a pediatric patient with the Takenouchi-Kosaki syndrome due to a heterozygous p.Tyr64Cys variant in CDC42 manifesting as a congenital malformation complex accompanied by macrothrombocytopenia, poor specific antibody response, B and T cell immunodeficiency, and low serum immunoglobulin A level. We also suggst that feeding disorders, malnutrition, and a gastrointestinal infection could be a part of the phenotypic characteristics of Takenouchi-Kosaki syndrome supporting the hypothesis of immune dysregulation and systemic inflammation occurring in the p.Tyr64Cys variant in CDC42.

Chromosome 22q11.2 Deletion Syndrome: A Comprehensive Review of Molecular Genetics in the Context of Multidisciplinary Clinical Approach.

The 22q11.2 deletion syndrome is a multisystemic disorder characterized by a marked variability of phenotypic features, making the diagnosis challenging for clinicians. The wide spectrum of clinical manifestations includes congenital heart defects-most frequently conotruncal cardiac anomalies-thymic hypoplasia and predominating cellular immune deficiency, laryngeal developmental defects, midline anomalies with cleft palate and velar insufficiency, structural airway defects, facial dysmorphism, parathyroid and thyroid gland hormonal dysfunctions, speech delay, developmental delay, and neurocognitive and psychiatric disorders. Significant progress has been made in understanding the complex molecular genetic etiology of 22q11.2 deletion syndrome underpinning the heterogeneity of clinical manifestations. The deletion is caused by chromosomal rearrangements in meiosis and is mediated by non-allelic homologous recombination events between low copy repeats or segmental duplications in the 22q11.2 region. A range of genetic modifiers and environmental factors, as well as the impact of hemizygosity on the remaining allele, contribute to the intricate genotype-phenotype relationships. This comprehensive review has been aimed at highlighting the molecular genetic background of 22q11.2 deletion syndrome in correlation with a clinical multidisciplinary approach.

Successful Treatment of Large B-Cell Lymphoma in a Child with Compound Heterozygous Mutation in the ATM Gene.

Ataxia-telangiectasia (AT) is a multisystemic neurodegenerative inborn error of immunity (IEI) characterized by DNA repair defect, chromosomal instability, and hypersensitivity to ionizing radiation. Impaired DNA double-strand break repair determines a high risk of developing hematological malignancies, especially lymphoproliferative diseases. Poor response to treatment, excessive chemotherapy toxicities, and the need for avoiding exposure to ionizing radiation make the successful clinical management of patients with AT challenging for oncologists. We describe the favorable outcome of the LBCL with IRF4 rearrangement at stage III in a 7-year-old female patient diagnosed with AT. The patient was treated according to the B-HR arm of the INTER-B-NHL-COP 2010 protocol, including the administration of rituximab, cyclophosphamide, methotrexate, prednisone, etc. She presented excessive treatment toxicities despite individually reduced doses of methotrexate and cyclophosphamide. However, in the MRI there was no significant reduction in pathologic lymph nodes after three immunochemotherapy courses. Therefore, a lymph node biopsy was taken. Its subsequent histopathological examination revealed tuberculosis-like changes, though tuberculosis suspicion was excluded. After two following immunochemotherapy courses, PET-CT confirmed complete remission. From March 2022 onwards, the patient has remained in remission under the care of the outpatient children's oncology clinic.

Infections and immune dysregulation in ataxia-telangiectasia children with hyper-IgM and non-hyper-IgM phenotypes: A single-center experience.

Ataxia-telangiectasia (A-T) is a severe syndromic neurodegenerative inborn error of immunity characterized by DNA reparation defect, chromosomal instability, and hypersensitivity to ionizing radiation, thereby predisposing affected individuals to malignant transformation. While the leading disease symptomatology is associated with progressively debilitating cerebellar ataxia accompanied by central and peripheral nervous system dysfunctions, A-T is a multisystemic disorder manifesting with the heterogeneity of phenotypic features. These include airway and interstitial lung disease, chronic liver disease, endocrine abnormalities, and cutaneous and deep-organ granulomatosis. The impaired thymic T cell production, defective B cell development and antibody production, as well as bone marrow failure, contribute to a combined immunodeficiency predisposing to infectious complications, immune dysregulation, and organ-specific immunopathology, with the A-T hyper-IgM (HIGM) phenotype determining the more severe disease course. This study aimed to clarify the immunodeficiency and associated immune dysregulation as well as organ-specific immunopathology in children with A-T. We also sought to determine whether the hyper-IgM and non-hyper-IgM phenotypes play a discriminatory role and have prognostic significance in anticipating the clinical course and outcome of the disease. We retrospectively reviewed the medical records of twelve A-T patients, aged from two to eighteen years. The patients' infectious history, organ-specific symptomatology, and immunological workup including serum alpha-fetoprotein, immunoglobulin isotypes, IgG subclasses, and lymphocyte compartments were examined. For further comparative analysis, all the subjects were divided into two groups, HIGM A-T and non-HIGM A-T. The clinical evaluation of the study group showed that recurrent respiratory tract infections due to viral and bacterial pathogens and a chronic obstructive airway disease along with impaired humoral immunity, in particular complete IgA deficiency, were noted in all the A-T patients, with both HIGM and non-HIGM phenotypes. The most important features with the discriminatory role between groups, were autoimmune disorders, observable four times more frequently in HIGM than in non-HIGM A-T. Two patients with the HIGM A-T phenotype were deceased due to liver failure and chronic Epstein-Barr virus (EBV) infection. It may therefore be assumed that the HIGM form of A-T is associated with more profound T cell dysfunction, defective immunoglobulin class switching, chronic EBV expansion, and poorer prognosis.

COVID-19 in unvaccinated patients with inborn errors of immunity-polish experience.

At the beginning of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic, patients with inborn errors of immunity (IEI) appeared to be particularly vulnerable to a severe course of the disease. It quickly turned out that only some IEI groups are associated with a high risk of severe infection. However, data on the course of Coronavirus Disease 2019 (COVID-19) in patients with IEI are still insufficient, especially in children; hence, further analyses are required. The retrospective study included 155 unvaccinated people with IEI: 105 children and 50 adults (67.7% and 32.3%, respectively). Male patients dominated in the study group (94 people, 60.6%). At least two comorbidities were found in 50 patients (32.3%), significantly more often in adults (56% vs. 21%). Adult patients presented significantly more COVID-19 symptoms. Asymptomatic and mildly symptomatic course of COVID-19 was demonstrated in 74.8% of the entire group, significantly more often in children (88.6% vs. 46%). Moderate and severe courses dominated in adults (54% vs. 11.4%). Systemic antibiotic therapy was used the most frequently, especially in adults (60% vs. 14.3%). COVID-19-specific therapy was used almost exclusively in adults. In the whole group, complications occurred in 14.2% of patients, significantly more often in adults (30% vs. 6.7%). In the pediatric group, there were two cases (1.9%) of multisystem inflammatory syndrome in children. Deaths were reported only in the adult population and accounted for 3.9% of the entire study group. The death rate for all adults was 12%, 15.4% for adults diagnosed with common variable immunodeficiency, 12.5% for those with X-linked agammaglobulinemia, and 21.4% for patients with comorbidity. The results of our study imply that vaccinations against COVID-19 should be recommended both for children and adults with IEI. Postexposure prophylaxis and early antiviral and anti-SARS-CoV-2 antibody-based therapies should be considered in adults with IEI, especially in those with severe humoral immune deficiencies and comorbidity.

Case report: The cardio-facio-cutaneous syndrome due to a novel germline mutation in MAP2K1: A multifaceted disease with immunodeficiency and short stature.

Cardio-facio-cutaneous syndrome (CFCS) belongs to the group of RASopathies, clinical disorders defined by disruptions in the RAS/MAPK signaling pathway. It is caused by heterozygous gain-of-function germline mutations in genes encoding protein kinases: BRAF, MAP2K1 (MEK1), MAP2K2 (MEK2), and in the GTPase-encoding gene KRAS. CFCS is characterized by craniofacial dysmorphic features, congenital heart defects, severe malnutrition, proportionate short stature, anomalies within the structure of skin and hair, and psychomotor disability. The pathophysiology of growth impairment is multifactorial with feeding difficulties, growth hormone deficiency, and insensitivity. Immunodeficiency has not been hitherto reported as an integral part of CFCS yet an increased activation of the RAS/MAPK signaling pathway may contribute to explaining the causal relationship between RASopathy and the dysfunctions within the B and T lymph cell compartments resulting in a deficiency in T cell costimulation and B cell maturation with impaired class switch recombination, somatic hypermutation, and high-affinity antibody production. We report on a boy born prematurely at 32 WGA, with the perinatal period complicated by pneumonia, respiratory distress syndrome, and valvular pulmonary stenosis. The boy suffered from recurrent pneumonia, obstructive bronchitis, sepsis, urinary tract infection, and recurrent fevers. He presented with severe hypotrophy, psychomotor disability, short stature, craniofacial dysmorphism, dental hypoplasia, sparse hair, and cryptorchidism. Whole genome sequencing showed a novel heterozygous pathogenic germline missense variant: c.364A > G; p.Asn122Asp in the MAP2K1 gene, supporting the diagnosis of CFCS. The immunological workup revealed hypogammaglobulinemia, IgG subclass, and specific antibody deficiency accompanied by decreased numbers of T helper cells and naive and memory B cells. Replacement immunoglobulin therapy with timely antibiotic prophylaxis were instituted. At the age of six years, growth hormone deficiency was diagnosed and the rGH therapy was started. The ever-increasing progress in genetic studies contributes to establishing the definitive CFCS diagnosis and sheds the light on the interrelated genotype-phenotype heterogeneity of RASopathies. Herein, we add new phenotypic features of predominating humoral immunodeficiency to the symptomatology of CFCS with a novel mutation in MAP2K1. While CFCS is a multifaceted disease, increased pediatricians' awareness is needed to prevent the delay in diagnostics and therapeutic interventions.

Imaging in children with ataxia-telangiectasia-The radiologist's approach.

Ataxia-telangiectasia (A-T) is a syndromic inborn error of immunity (IEI) characterized by genomic instability, defective reparation of the DNA double-strand breaks, and hypersensitivity to ionizing radiation disturbing cellular homeostasis. The role of imaging diagnostics and the conscious choice of safe and advantageous imaging technique, as well as its correct interpretation, are crucial in the diagnostic process and monitoring of children with A-T. This study aimed at defining the role of a radiologist in the early diagnosis of A-T, as well as in detecting and tracking disease complications associated with infections, inflammation, lymphoproliferation, organ-specific immunopathology, and malignancy. Based on our single-center experience, retrospective analysis of investigations using ionizing radiation-free techniques, ultrasound (US), and Magnetic Resonance Imaging (MRI), was performed on regularly followed-up 11 pediatric A-T patients, 6 girls and 5 boys, aged from 2 to 18 years, with the longest period of observation coming to over 13 years. Our attention was especially drawn to the abnormalities that were observed in the US and MRI examinations of the lungs, abdominal cavity, and lymph nodes. The abdominal US showed no abnormalities in organ dimensions or echostructure in 4 out of 11 children studied, yet in the other 7, during follow-up examinations, hepato- and/or splenomegaly, mesenteric, visceral, and paraaortic lymphadenopathy were observable. In 2 patients, focal changes in the liver and spleen were shown, and in one patient progressive abdominal lymphadenopathy corresponded with the diagnosis of non-Hodgkin lymphoma (NHL). The lung US revealed multiple subpleural consolidations and B line artifacts related to the interstitial-alveolar syndrome in 5 patients, accompanied by pleural effusion in one of them. The MRI investigation of the lung enabled the detection of lymphatic nodal masses in the mediastinum, with concomitant airway lesions characteristic of bronchiectasis and focal parenchymal consolidations in one A-T patient with chronic respiratory failure. This patient also manifested organomegaly and granulomatous liver disease in abdominal MRI examination. Our study shows that the use of modern US capabilities and MRI is safe and efficient, thereby serving as a recommended advantageous imaging diagnostic tool in monitoring children with IEI and DNA instability syndromes.

Clinical and immunological assessment of APDS2 with features of the SHORT syndrome related to a novel mutation in PIK3R1 with reduced penetrance.

Monoallelic loss-of-function (LOF) mutations in the phosphatidylinositol 3-kinase (PIK3R1) gene affecting the inter-Src homology 2 domain of the p85α regulatory subunit of phosphoinositide--3-kinase δ (PI3Kδ) cause the activated PI3K δ syndrome (APDS2). APDS2 is defined as a primary antibody deficiency, developmental abnormalities within the B and T lymph cell compartments, and immune dysregulation. The genetic defect of APDS2 is shared with that of the SHORT syndrome, characterized by short stature, joint hyperextensibility, ocular depression, Rieger anomaly, and delayed tooth eruption. LOF variants in an intronic splice site (c.1425+1G.C/A/T) in the PI3KR1 gene have been identified in patients affected with both APDS2 and SHORT syndrome. Herein, we report a novel c.1644-1648del (p.Asp548Glufs*6) variant in a pediatric patient with the APDS2-related immunodeficiency, who presents with mild phenotypic features of the SHORT syndrome, congenital chest wall deformity, and IgE-mediated food allergy. The same variant was also identified in the patient's hitherto asymptomatic mother, implicating an incomplete penetrance. Regular monitoring by a multidisciplinary team under the pediatric clinical immunologist's supervision to implement appropriate diagnostic procedures and treatment modalities is of paramount importance. Further studies are required to better define the genotype-phenotype correlation in patients with the PIK3R1 gene mutations and to better delineate the mutual relationship between APDS2 and the SHORT syndrome.

Immune Dysregulation in Pediatric Common Variable Immunodeficiency: Implications for the Diagnostic Approach.

Infections and infectious complications are hallmarks of common variable immunodeficiency (CVID) and the leading cause of morbidity and mortality in affected patients at any age. However, the pediatric CVID is no longer perceived as a primary immunodeficiency associated solely with infectious manifestations; autoimmune, allergic, lymphoproliferative, and malignant disorders and organ-specific immunopathology also characterize the spectrum of non-infectious complications. In this study, we sought to determine the role of immune dysregulation and frequency of non-infectious sequelae in children affected with CVID. We also aimed at providing an insight into the pathogenesis of non-infectious complications and at delineating the diagnostic approach to pediatric CVID with immune dysregulation. An in-depth retrospective analysis of clinical manifestations and their correlations with selected immune parameters was performed in a group of 39 CVID children, followed by our pediatric immunology department. Whereas recurrent sinopulmonary infections were present in all (100%) of the children studied, an unexpectedly high rate of non-infectious disorders and immune dysregulation phenotypes were observed in as many as 32 (82.05%) patients, compared with infection-only phenotypes limited to 7 (17.95%) male patients. The most common inflammatory comorbidity was asthma, diagnosed in 21 (53.85%) patients. The second most frequent immune dysregulation group was autoimmune disorders, present in 18 (46.15%) of the children studied with a high rate of autoimmune thyroiditis in as many as 10 (25.64%) of the CVID-affected children. Lymphoproliferation was seen in 14 children (35.90%), and, among them, lymphadenopathy occurred in nine (23.08%) cases and granulomatous lymphocytic interstitial lung disease in seven (17.95%) cases. Finally, malignancies occurred in two female patients (5.13%), papillary thyroid cancer in the first one and T-cell lymphoblastic leukemia in the other one. The most prominent abnormalities in the B- and T-cell compartment contributing to complex immune deficiency and immune dysregulation phenotypes were seen in the autoimmunity group, showing significant reductions in the switched memory B cell, naive T helper cell, and regulatory T-cell subsets. Herein, we document the previously unreported high rate of immune dysregulation in pediatric CVID as a clinical and diagnostic challenge with the variability of defects in the humoral and cellular immune responses.

The pediatric common variable immunodeficiency - from genetics to therapy: a review.

Common variable immunodeficiency (CVID) is the most prevalent antibody deficiency, characterized by remarkable genetic, immunological, and clinical heterogeneity. The diagnosis of pediatric CVID is challenging due to the immaturity of the immune response and sustained actively developing antibody affinity to antigens and immunological memory that may overlap with the inborn error of immunity. Significant progress has been recently done in the field of immunogenetics, yet a paucity of experimental and clinical studies on different systemic manifestations and immunological features of CVID in children may contribute to a delayed diagnosis and therapy. In this review, we aimed at defining the variable epidemiological, etiological, and clinical aspects of pediatric CVID with special emphasis on predominating infectious and non-infectious phenotypes in affected children. CONCLUSION: While pediatric CVID is a multifaceted and notorious disease, increasing the pediatricians' awareness of this disease entity and preventing the diagnostic and therapeutic delay are needed, thereby improving the prognosis and survival of pediatric CVID patients. WHAT IS KNOWN: • CVID is an umbrella diagnosis characterized by complex pathophysiology with an antibody deficiency as a common denominator. • It is a multifaceted disease characterized by marked genetic, immunological, and clinical heterogeneity.. WHAT IS NEW: • The diagnosis of pediatric CVID is challenging due to the immaturity of innate and adaptive immune response. • Increasing the pediatricians' awareness of CVID for the early disease recognition, timely therapeutic intervention, and improving the prognosis is needed.

Syndromic immunodeficiencies: a pediatrician's perspective on selected diseases.

BACKGROUND: Syndromic immunodeficiencies are a genetically and pathophysiologically heterogeneous group of inborn errors of immunity. These are characterized by multiple extra immune clinical symptoms and a wide range of immunological phenotypes with increased susceptibility to infections, autoimmune phenomena, immune dysregulation, organ-specific pathology, and malignancy. OBJECTIVE: To increase the pediatricians' awareness of this multifaceted group of primary immunodeficiencies in children. METHODS: A comprehensive review of genetic background and clinical symptomatology of syndromic immunodeficiencies as well as current diagnostic approach and treatment modalities. RESULTS: From the pediatrician's perspective, an early-life diagnosis of syndromic immunodeficiencies, which is frequently indispensable for successful life-saving immunocorrection, poses a diagnostic challenge. Increased pediatricians' awareness to recognize signs and symptoms of these diseases in affected children is of paramount importance. Current advances in molecular biotechnology and immunogenetics, resulting in the implementation of newborn screening and new-generation sequencing, provide informative tools for definitive diagnosis and, in many new disease entities, for their definition and genotype-phenotype delineation and correlation. CONCLUSIONS: A broad spectrum of clinical phenotypes in children with syndromic primary immunodeficiencies requires pediatrician's special attention, that is, individualized multidisciplinary approach under the supervision of a clinical immunologist.

Granulomatous Lymphocytic Interstitial Lung Disease in a Spectrum of Pediatric Primary Immunodeficiencies.

BACKGROUND: Granulomatous lymphocytic interstitial lung disease (GLILD) has been increasingly recognized in children affected with primary immunodeficiencies (PIDs). In this study, we aimed to better characterize the spectrum of pediatric PIDs coexisting with GLILD including clinical and immunological predictors, thoracic imaging findings, and histopathologic features. METHODS: We respectively reviewed records of six representative cases of children, three of them affected with common variable immunodeficiency (CVID) and three with syndromic immunodeficiencies, in whom a diagnosis of GLILD was established based on clinical, radiological, and histopathologic findings. Clinical and immunological predictors for GLILD were also analyzed in the patients studied. RESULTS: All the children with GLILD had a history of autoimmune phenomena, organ-specific immunopathology, and immune dysregulation. Defective B-cell maturation and deficiency of memory B cells were found in all the children with GLILD. The radiological and histopathological features consistent with the diagnosis of GLILD, granulomatous disease, and lymphoid hyperplasia, were accompanied by chronic airway disease with bronchiectasis in children with CVID and syndromic PIDs. CONCLUSIONS: Our study shows that both CVID and syndromic PIDs may be complicated with GLILD. Further studies are required to understand the predictive value of coexisting autoimmunity and immune dysregulation in the recognition of GLILD in children with PIDs.

The CXCR5 T follicular helper cell compartment in children with antibody deficiencies-in search of a prognostic marker of childhood hypogammaglobulinemia.

BACKGROUND: Novel immunodiagnostic markers are required in order to discriminate between mild hypogammaglobulinemia and severe humoral primary immune deficiencies in children. The efficacy of an antibody response to infections and vaccines is underpinned by T follicular helper (Tfh) cells, activating an immunoglobulin class switch recombination, somatic hypermutations, and affinity maturation. OBJECTIVE: To determine the formation of the Tfh cells in antibody deficient children and to define their importance as prognostic markers helpful in defining the severity of hypogammaglobulinemia. METHODS: We retrospectively reviewed medical records of 200 children aged from 2 months to 10 years, in whom hypogammaglobulinemia was assessed, from January to December 2019. In all the children studied, a flow cytometric analysis of the Tfh cell compartment was performed. RESULTS: In young infants aged from 2 to 9 months, the mean relative frequency of the Tfh population was lower than in the control population. Concomitantly, the relative values of Tfh cells, corresponding with the 95th percentile, were below the reference values in all age groups. CONCLUSIONS: A deficiency of Tfh cells in young infants mirrors the immaturity of the humoral immune response, whereas in older children Tfh cells are proposed as a prognostic marker facilitating to distinguish between mild hypogammaglobulinemia and the developing common variable immunodeficiency.

Mosaic IL6ST variant inducing constitutive GP130 cytokine receptor signaling as a cause of neonatal onset immunodeficiency with autoinflammation and dysmorphy.

Interleukin-6 signal transducer (IL6ST) encodes the GP130 protein which transduces the proinflammatory signaling of the IL6 cytokine family through Janus kinase signal transducers and activators of transcription pathway (JAK/STAT) activation. Biallelic loss-of-function IL6ST variants cause autosomal recessive hyper-IgE syndrome or a variant of the Stuve-Wiedemann syndrome. Somatic gain-of-function IL6ST mutations, in particular, small monoallelic in-frame deletions of which the most prevalent is the IL6ST Ser187_Tyr190del, are an established cause of inflammatory hepatocellular tumors, but so far, no disease caused by such mutations present constitutively has been described. Herein, we report a pediatric proband with a novel syndrome of neonatal onset immunodeficiency with autoinflammation and dysmorphy associated with the IL6ST Tyr186_Tyr190del variant present constitutively. Tyr186_Tyr190del was found by exome sequencing and was shown to be de novo (absent in proband's parents and siblings) and mosaic (present in approximately 15-40% of cells depending on the tissue studied-blood, urine sediment, hair bulbs and buccal swab). Functional studies were performed in the Epstein-Barr virus-immortalized patient's B cell lymphoblastoid cell line, which carried the variant in approximately 95% of the cells. Western blot showed that the patient's cells exhibited constitutive hyperphosphorylation of Tyr705 in STAT3, which is indicative of IL6-independent activation of GP130. Interestingly, the STAT3 phosphorylation could be inhibited with ruxolitinib as well as tofacitinib, which are clinically approved JAK1 and JAK3 (to lesser extent JAK2 and JAK1) inhibitors, respectively. Given our results and the recent reports of ruxolitinib and tofacitinib use for the treatment of diseases caused by direct activation of STAT3 or STAT1, we speculate that these drugs may be effective in the treatment of our patient's condition.

Case Report: Autoimmune Lymphoproliferative Syndrome vs. Chronic Active Epstein-Barr Virus Infection in Children: A Diagnostic Challenge.

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder characterized by a disruption of the lymphocyte apoptosis pathway, self-tolerance, and immune system homeostasis. Defects in genes within the first apoptosis signal (FAS)-mediated pathway cause an expansion of autoreactive double-negative T cells leading to non-malignant lymphoproliferation, autoimmune disorders, and an increased risk of lymphoma. The aim of the study was to show the diagnostic dilemmas and difficulties in the process of recognizing ALPS in the light of chronic active Epstein-Barr virus (CAEBV) infection. Clinical, immunological, flow cytometric, biomarkers, and molecular genetic approaches of a pediatric patient diagnosed with FAS-ALPS and CAEBV are presented. With the ever-expanding spectrum of molecular pathways associated with autoimmune lymphoproliferative disorders, multiple genetic defects of FAS-mediated apoptosis, primary immunodeficiencies with immune dysregulation, malignant and autoimmune disorders, and infections are included in the differential diagnosis. Further studies are needed to address the issue of the inflammatory and neoplastic role of CAEBV as a triggering and disease-modifying factor in ALPS.

Granulomatous Liver Disease in Ataxia-Telangiectasia With the Hyper-IgM Phenotype: A Case Report.

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by neurodegeneration, combined immunodeficiency, and oculocutaneous telangiectasia. The hyper-IgM phenotype of A-T, correlating with a class-switch recombination defect, IgG and IgA deficiency, T helper and B cell lymphopenia, immune dysregulation, proinflammatory immune response, autoimmune disease, and a high risk of lymphomagenesis. Progressive liver disease is a hallmark of classical A-T with the hyper-IgM phenotype and manifests as non-alcoholic hepatic steatosis and fibrosis. We report a case of a 17-year-old male A-T patient, in whom a progressive granulomatous liver disease with portal hypertension, has led to massive splenomegaly and hypersplenism, metabolic liver insufficiency, bleeding from esophageal varices and pancytopenia. In this patient, an unusual severe disease course with a highly variable constellation of A-T symptomatology includes granulomatous skin, visceral, and internal organs disease with liver involvement. The liver disease is associated with the hyper-IgM immunophenotype and escalating neurodegeneration, creating a vicious circle of immune deficiency, permanent systemic inflammatory response, and organ-specific immunopathology.

Cutaneous and systemic granulomatosis in ataxia-telangiectasia: a clinico-pathological study.

INTRODUCTION: The development of granulomas is a well-recognized manifestation of immunodeficiency in ataxia-telangiectasia (A-T), resulting from lymphocyte developmental abnormalities, impaired immunosurveillance, and inappropriate innate immune response-driven inflammation. AIM: To better understand pathological and immunological phenomena involved in development of cutaneous and visceral granulomatosis observable in patients with ataxia-telangiectasia. MATERIAL AND METHODS: We retrospectively reviewed medical records of eight A-T children, aged from 2 to 13 years, with regard to clinical, immunological and histopathological features of cutaneous and visceral granulomatosis. RESULTS: In four out of eight A-T patients studied, cutaneous granulomas clinically presented as skin nodules and ulcerated erythematous plaques disseminated on the face, and on trauma-prone areas of upper and lower extremities. Visceral granulomatosis had a severe clinical course and involved the lungs, the spleen, the liver and the larynx. Histologically, cutaneous and laryngeal granulomas showed extensive cellular infiltrations containing T lymphocytes with predominating CD8+ phenotype and with CD68+ histiocytes. The immunological profile with the hyper-IgM phenotype, markedly reduced numbers of B and naive CD4+ and CD8+ T cells with predominating IgM-only memory B cells and skewed repertoire of a T cell receptor was observable in patients with skin and visceral granulomatosis. CONCLUSIONS: In the setting of combined immunodeficiency in A-T, cutaneous and systemic granulomatosis reflects a granulomatous reaction pattern, as a result of inappropriate immune regulation.

Factors causing oral and skin pathological features in the hyperimmunoglobulin E syndrome patient including the environmental component: a review of the literature and own experience.

The hyperimmunoglobulin E syndrome (HIES) is a rare multi-system disease with non-immunological as well as immunological abnormalities. The syndrome is characterized by a triad of the most distinctive symptoms, such as pneumonia with pneumatocele formation, recurring staphylococcal skin abscesses and a high serum concentration of IgE. Central mediators of immune responses such as STAT1 and STAT3 affect immune responses and contribute to changes of the skin microbiome which subsequently can amplify the defective immune response against microbial and fungal pathogens. Reactions related to an environmental factor, such as sun-induced skin changes, in individuals during long-term medication therapy have also been reported. The dermatological symptoms, oral status and other health problems of a hyperimmunoglobulin E syndrome paediatric patient are presented. HIES is of great importance to different professionals because sufferers require special preventive and therapeutic management from early infancy in order to avoid complications which can even prove to be life-saving for such patients.