Cancer Prevalence in Children with Inborn Errors of Immunity: Report from a Single Institution.

BACKGROUND: Inborn Errors of Immunity (IEI) comprise several genetic anomalies that affect different components of the innate and adaptive responses, predisposing to infectious diseases, autoimmunity and malignancy. Different studies, mostly in adults, have reported a higher prevalence of cancer in IEI patients. However, in part due to the rarity of most of these IEI subtypes (classified in ten categories by the Primary Immunodeficiency Committee of the International Union of Immunological Societies), it is difficult to assess the risk in a large number of patients, especially during childhood. OBJECTIVE: To document the cancer prevalence in a pediatric cohort from a single referral institution, assessing their risk, together with the type of neoplasia within each IEI subgroup. METHOD: An extensive review of clinical records from 1989 to 2022 of IEI patients who at some point developed cancer before the age of sixteen. RESULTS: Of a total of 1642 patients with IEI diagnosis, 34 developed cancer before 16 years of age, showing a prevalence (2.1%) significantly higher than that of the general age matched population (0.22). Hematologic neoplasms (mostly lymphomas) were the most frequent malignancies. CONCLUSION: This study represents one of the few reports focused exclusively in pediatric IEI cases, describing not only the increased risk of developing malignancy compared with the age matched general population (a fact that must be taken into account by immunologists during follow-up) but also the association of the different neoplasms with particular IEI subtypes, thus disclosing the possible mechanisms involved.

STAT3 gain-of-function mutation in an adult patient.

Germline gain-of-function (GOF) mutation of the signal transducer and activator of transcription 3 (STAT3) gene causes a disease clinically characterized by a significant lymphoproliferation, including lymphadenopathy and/or hepatosplenomegaly, as well as childhood onset autoimmunity. Here we present an adult patient who, during his early years of life, presented recurrent infections, autoimmune hemolytic anemia and benign lymphoproliferative disease, characterized by hepatosplenomegaly and lymphadenopathy, being diagnosed with common variable immunodeficiency (CVID) at 13 years of age. He was diagnosed with lymphocytic interstitial pneumonia at the age of 20. When he was 40 years old, after a diagnostic review, it was decided to perform genetic studies. A heterozygous mutation in STAT3 NM_003150 c.2141C>T, p.P714L was detected by whole exome sequencing and validated by Sanger. Previously published functional studies performed in two siblings showed that this mutation resulted in gain-of-function. They were initially diagnosed with autoimmune lymphoproliferative syndrome, and later with STAT3 GOF as a second genetic defect. Our patient developed severe pulmonary disease and died, without access to treatment targeted to his molecular defect due to the advanced nature of his pulmonary involvement and the fact that many of the therapies were still in development at that time. The diagnosis of STAT3 GOF mutations should be suspected in patients with early-onset of lymphoproliferative disease, autoimmunity and hypogammaglobulinemia. This must be considered especially in the group of CVID patients with these characteristics, in order to allow the implementation of treatments targeting the molecular defect (JAK inhibitors and Il-6 receptor antagonists) that could modify the disease evolution.

Mutaciones en línea germinal con ganancia de función (GOF) del gen transductor de señales y activador de la transcripción 3 (STAT3) provocan una enfermedad caracterizada por importante linfoproliferación, incluyendo linfadenopatías y/o hepatoesplenomegalia, así como autoinmunidad de inicio en la infancia. Presentamos un paciente adulto que, durante sus primeros años de vida, presentó infecciones recurrentes, anemia hemolítica autoinmune y enfermedad linfoproliferativa benigna, caracterizada inicialmente por hepatoesplenomegalia y linfoadenopatías, diagnosticado de inmunodeficiencia común variable (IDCV) a los 13 años. A los 20 años, al ser estudiado por compromiso pulmonar, se diagnosticó neumonía intersticial linfocítica. A los 40 años, tras revisión diagnóstica se decidió realizar estudios genéticos. Por secuenciación del exoma completo se detectó una mutación heterocigota en STAT3 NM_003150 c.2141C>T, p.P714L, que se validó por Sanger. Estudios funcionales previamente publicados realizados en dos hermanos con diagnóstico inicial de síndrome linfoproliferativo autoinmune, mostraron que esta mutación daba lugar a una ganancia de función. Nuestro paciente desarrolló enfermedad pulmonar grave y falleció a los 41 años, sin posibilidad de acceder a tratamiento dirigido a su defecto molecular por lo avanzado de su compromiso pulmonar y a que muchas de las terapias se encontraban en ese momento en desarrollo. El diagnóstico de mutaciones STAT3 GOF debe sospecharse en pacientes con enfermedad linfoproliferativa temprana, autoinmunidad e hipogammaglobulinemia. Esto debe ser considerado especialmente en pacientes con IDCV con estas carac terísticas, para permitir la implementación de tratamientos dirigidos al defecto molecular (inhibidores de JAK y antagonistas del receptor de Il-6) que podrían modificar la evolución de la enfermedad.

STAT3 gain-of-function mutation in an adult patient / Paciente adulto portador de una mutación con ganancia de función en el gen STAT3

Abstract Germline gain-of-function (GOF) mutation of the signal transducer and activator of transcription 3 (STAT3) gene causes a disease clinically characterized by a significant lymphoproliferation, includ ing lymphadenopathy and/or hepatosplenomegaly, as well as childhood onset autoimmunity. Here we present an adult patient who, during his early years of life, presented recurrent infections, autoimmune hemolytic anemia and benign lymphoproliferative disease, characterized by hepatosplenomegaly and lymphadenopathy, being diagnosed with common variable immunodeficiency (CVID) at 13 years of age. He was diagnosed with lymphocytic interstitial pneumonia at the age of 20. When he was 40 years old, after a diagnostic review, it was decided to perform genetic studies. A heterozygous mutation in STAT3 NM_003150 c.2141C>T, p.P714L was detected by whole exome sequencing and validated by Sanger. Previously published functional studies performed in two siblings showed that this mutation resulted in gain-of-function. They were initially diagnosed with autoimmune lymphoproliferative syndrome, and later with STAT3 GOF as a second genetic defect. Our patient developed severe pulmonary disease and died, without access to treatment targeted to his molecular defect due to the advanced nature of his pulmonary involvement and the fact that many of the therapies were still in develop ment at that time. The diagnosis of STAT3 GOF mutations should be suspected in patients with early-onset of lymphoproliferative disease, autoimmunity and hypogammaglobulinemia. This must be considered especially in the group of CVID patients with these characteristics, in order to allow the implementation of treatments target ing the molecular defect (JAK inhibitors and Il-6 receptor antagonists) that could modify the disease evolution.

Resumen Mutaciones en línea germinal con ganancia de función (GOF) del gen transductor de señales y acti vador de la transcripción 3 (STAT3) provocan una enfermedad caracterizada por importante linfoproliferación, incluyendo linfadenopatías y/o hepatoesplenomegalia, así como autoinmunidad de inicio en la infancia. Presen tamos un paciente adulto que, durante sus primeros años de vida, presentó infecciones recurrentes, anemia hemolítica autoinmune y enfermedad linfoproliferativa benigna, caracterizada inicialmente por hepatoespleno megalia y linfoadenopatías, diagnosticado de inmunodeficiencia común variable (IDCV) a los 13 años. A los 20 años, al ser estudiado por compromiso pulmonar, se diagnosticó neumonía intersticial linfocítica. A los 40 años, tras revisión diagnóstica se decidió realizar estudios genéticos. Por secuenciación del exoma completo se detectó una mutación heterocigota en STAT3 NM_003150 c.2141C>T, p.P714L, que se validó por Sanger. Estudios funcionales previamente publicados realizados en dos hermanos con diagnóstico inicial de síndrome linfoproliferativo autoinmune, mostraron que esta mutación daba lugar a una ganancia de función. Nuestro pa ciente desarrolló enfermedad pulmonar grave y falleció a los 41 años, sin posibilidad de acceder a tratamiento dirigido a su defecto molecular por lo avanzado de su compromiso pulmonar y a que muchas de las terapias se encontraban en ese momento en desarrollo. El diagnóstico de mutaciones STAT3 GOF debe sospecharse en pacientes con enfermedad linfoproliferativa temprana, autoinmunidad e hipogammaglobulinemia. Esto debe ser considerado especialmente en pacientes con IDCV con estas características, para permitir la implementación de tratamientos dirigidos al defecto molecular (inhibidores de JAK y antagonistas del receptor de Il-6) que podrían modificar la evolución de la enfermedad.

Clinical Manifestations, Mutational Analysis, and Immunological Phenotype in Patients with RAG1/2 Mutations: First Cases Series from Mexico and Description of Two Novel Mutations.

Mutations in recombinase activating genes 1 and 2 (RAG1/2) result in human severe combined immunodeficiency (SCID). The products of these genes are essential for V(D)J rearrangement of the antigen receptors during lymphocyte development. Mutations resulting in null-recombination activity in RAG1 or RAG2 are associated with the most severe clinical and immunological phenotypes, whereas patients with hypomorphic mutations may develop leaky SCID, including Omenn syndrome (OS). A group of previously unrecognized clinical phenotypes associated with granulomata and/or autoimmunity have been described as a consequence of hypomorphic mutations. Here, we present six patients from unrelated families with missense variants in RAG1 or RAG2. Phenotypes observed in these patients ranged from OS to severe mycobacterial infections and granulomatous disease. Moreover, we report the first evidence of two variants that had not been associated with immunodeficiency. This study represents the first case series of RAG1- or RAG2-deficient patients from Mexico and Latin America.

PI3K pathway defects leading to immunodeficiency and immune dysregulation.

The phosphatidylinositol 3-kinase (PI3K) signaling pathway is involved in a broad range of cellular processes, including growth, metabolism, differentiation, proliferation, motility, and survival. The PI3Kδ enzyme complex is primarily present in the immune system and comprises a catalytic (p110δ) and regulatory (p85α) subunit. Dynamic regulation of PI3Kδ activity is required to ensure normal function and differentiation of immune cells. In the last decade, discovery of germline mutations in genes involved in the PI3Kδ pathway (PIK3CD, PIK3R1, or phosphatase and tensin homolog [PTEN]) proved that both overactivation and underactivation (gain of function and loss of function, respectively) of PI3Kδ lead to impaired and dysregulated immunity. Although a small group of patients reported to underactivate PI3Kδ show predominantly humoral defects and autoimmune features, more than 200 patients have been described with overactivation of PI3Kδ, presenting with a much more complex phenotype of combined immunodeficiency and immune dysregulation. The clinical and immunologic characterization, as well as current pathophysiologic understanding and specific therapies for PI3K pathway defects leading to immunodeficiency and immune dysregulation, are reviewed here.

Bacille Calmette-Guerin Complications in Newly Described Primary Immunodeficiency Diseases: 2010-2017.

Bacille Calmette-Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. BCG is a live vaccine, usually given early in life in most countries. While safe to most recipients, it poses a risk to immunocompromised patients. Several primary immunodeficiency diseases (PIDD) have been classically associated with complications related to BCG vaccine. However, a number of new inborn errors of immunity have been described lately in which little is known about adverse reactions following BCG vaccination. The aim of this review is to summarize the existing data on BCG-related complications in patients diagnosed with PIDD described since 2010. When BCG vaccination status or complications were not specifically addressed in those manuscripts, we directly contacted the corresponding authors for further clarification. We also analyzed data on other mycobacterial infections in these patients. Based on our analysis, around 8% of patients with gain-of-function mutations in STAT1 had mycobacterial infections, including localized complications in 3 and disseminated disease in 4 out of 19 BCG-vaccinated patients. Localized BCG reactions were also frequent in activated PI3Kδ syndrome type 1 (3/10) and type 2 (2/18) vaccinated children. Also, of note, no BCG-related complications have been described in either CTLA4 or LRBA protein-deficient patients; and not enough information on BCG-vaccinated NFKB1 or NFKB2-deficient patients was available to drive any conclusions about these diseases. Despite the high prevalence of environmental mycobacterial infections in GATA2-deficient patients, only one case of BCG reaction has been reported in a patient who developed disseminated disease. In conclusion, BCG complications could be expected in some particular, recently described PIDD and it remains a preventable risk factor for pediatric PIDD patients.

Successful immune reconstitution by means of hematopoietic stem cell transplantation in a Colombian patient with chronic granulomatous disease.

INTRODUCTION: Chronic granulomatous disease is a primary immunodeficiency that results from mutations in proteins of the NADPH oxidase system that affect the microbicidal activity of phagocytes. Immune reconstitution by hematopoietic stem cell transplantation is currently the only curative therapy for this disease.  OBJECTIVE: To describe the clinical and molecular characterization of a patient with X-linked chronic granulomatous disease and the successful immune reconstitution by means of a hematopoietic stem cell transplantation.  METHODS: The respiratory burst was measured by flow cytometry using the dihydrorodamine 123 (DHR) oxidation test in neutrophils of peripheral blood. Mutational analysis of CYBB was performed by PCR amplification in complementary DNA, as well as sequencing and comparative genomic hybridization in genomic DNA. HLA-identical stem cells from the patient's younger brother were used for the transplantation and reduced intensity pre-transplantation conditioning was administered. Post-transplantation immune reconstitution was evaluated periodically by serial complete blood counts and DHR 123 in peripheral blood neutrophils.  RESULTS: The diagnosis of X-linked chronic granulomatous disease resulted from a hemizygous deletion affecting Xp21.1 that included the entire CYBB. Post-transplantation engraftment was documented in platelets and peripheral blood neutrophils at days 10 and 11, respectively. Total hematological reconstitution was achieved by day 30 post-transplantation and no complications or infections have been observed in the three years since the transplantation.  CONCLUSION: Hemopoietic stem cell transplantation allows for total reconstitution of the immune function related to microbicidal activity of phagocytic cells from patients with X-linked chronic granulomatous disease.

Reconstitución inmune exitosa mediante trasplante de células madre hematopoyéticas en un paciente colombiano afectado con enfermedad granulomatosa crónica / Successful immune reconstitution by means of hematopoietic stem cell transplantation in a Colombian patient with chronic granulomatous disease

Introducción. La enfermedad granulomatosa crónica es una inmunodeficiencia primaria causada por mutaciones en los genes que codifican para las proteínas del sistema de la oxidasa de NADPH ( Nicotinamide Adenine Dinucleotide Phosphate ) de las células fagocíticas, las cuales afectan la producción de especies reactivas del oxígeno y la actividad microbicida. Actualmente, la única terapia curativa para esta enfermedad es la reconstitución inmune mediante el trasplante de células madre hematopoyéticas. Objetivo. Reportar la caracterización clínica y molecular de un paciente con enfermedad granulomatosa crónica ligada al cromosoma X y su reconstitución inmunitaria exitosa mediante el trasplante de células madre hematopoyéticas. Materiales y métodos. El estallido respiratorio en neutrófilos de sangre periférica se midió por citometría de flujo mediante la prueba de oxidación de la dihidrorrodamina 123 (DHR 123). El análisis de las mutaciones del gen CYBB se hizo mediante reacción en cadena de la polimerasa (PCR) en el ADN complementario y la secuenciación e hibridación genómica comparativa en el ADN genómico. En el trasplante se emplearon células madre del hermano menor con HLA idéntico, y previamente se hizo un acondicionamiento de intensidad reducida. La reconstitución inmunitaria después del trasplante se evaluó periódicamente con hemoleucogramas y la prueba DHR 123 en neutrófilos de sangre periférica. Resultados. El diagnóstico de la enfermedad granulomatosa crónica ligada al cromosoma X se estableció como resultado de una deleción hemicigota en la banda Xp21.1 que implicó la deleción completa del CYBB . La toma de injerto postrasplante para plaquetas y neutrófilos fue en los días 10 y 11, respectivamente. En el día 30 después del trasplante se logró la reconstitución hematológica completa y en los tres años siguientes no se observaron complicaciones ni infecciones. Conclusión. El trasplante de células madre hematopoyéticas permite la reconstitución completa de la función inmunitaria relacionada con la actividad microbicida de las células fagocíticas de pacientes con enfermedad granulomatosa crónica ligada al cromosoma X.

Introduction: Chronic granulomatous disease is a primary immunodeficiency that results from mutations in proteins of the NADPH oxidase system that affect the microbicidal activity of phagocytes. Immune reconstitution by hematopoietic stem cell transplantation is currently the only curative therapy for this disease. Objective: To describe the clinical and molecular characterization of a patient with X-linked chronic granulomatous disease and the successful immune reconstitution by means of a hematopoietic stem cell transplantation. Materials and methods: The respiratory burst was measured by flow cytometry using the dihydrorodamine 123 (DHR) oxidation test in neutrophils of peripheral blood. Mutational analysis of CYBB was performed by PCR amplification in complementary DNA, as well as sequencing and comparative genomic hybridization in genomic DNA. HLA-identical stem cells from the patient´s younger brother were used for the transplantation and reduced intensity pre-transplantation conditioning was administered. Post-transplantation immune reconstitution was evaluated periodically by serial complete blood counts and DHR 123 in peripheral blood neutrophils. Results: The diagnosis of X-linked chronic granulomatous disease resulted from a hemizygous deletion affecting Xp21.1 that included the entire CYBB . Post-transplantation engraftment was documented in platelets and peripheral blood neutrophils at days 10 and 11, respectively. Total hematological reconstitution was achieved by day 30 post-transplantation and no complications or infections have been observed in the three years since the transplantation. Conclusion: Hemopoietic stem cell transplantation allows for total reconstitution of the immune function related to microbicidal activity of phagocytic cells from patients with X-linked chronic granulomatous disease.

Leucocyte adhesion deficiency type 1 with developmental delay secondary to CMV infection and filiation questions.

Leucocyte adhesion deficiency (LAD) is a group of rare autosomal recessive (<1:1 000 000 births) inherited disorders characterised by immune deficiency and peripheral neutrophilia. Three types of LAD syndrome have been distinguished. LAD type 1 (LAD-I) is the most common. It results from a mutation in the integrin ß 2 (ITGB2) gene that codes the ITGB subunit (CD18 antigen). Since 1970, it has been reported in more than 300 children worldwide. It is characterised by delayed separation of the umbilical cord, recurrent bacterial and fungal infections, defective wound healing, blood neutrophilia and a high mortality rate at an early age. We report the second fatal case of an infant with LAD-I diagnosed in Chile, with developmental delay associated with a congenital cytomegalovirus infection. CD18/CD11 expression was normal. Genetic analysis of CD18 revealed a homozygous mutation in ITGB2, viz.c.1835G>T; p.C612F, and led us to suspect a biological parent other than the legal father and, therefore, an unwanted social situation.

A novel internalization motif regulates human IFN-γ R1 endocytosis.

This study tested the hypothesis that the IFN-γ R1 287-YVSLI-91 intracellular motif regulates its endocytosis. IFN-γ exerts its biological activities by interacting with a specific cell-surface RC composed of two IFN-γ R1 and two IFN-γ R2 chains. Following IFN-γ binding and along with the initiation of signal transduction, the ligand and IFN-γ R1 are internalized. Two major types of consensus-sorting signals are described in receptors, which are rapidly internalized from the plasma membrane to intracellular compartments: tyrosine-based and dileucine-based internalization motifs. Transfection of HEK 293 cells and IFN-γ R1-deficient fibroblasts with WT and site-directed, mutagenesis-generated mutant IFN-γ R1 expression vectors helped us to identify region IFN-γ R1 287-YVSLI-291 as the critical domain required for IFN-γ-induced IFN-γ R1 internalization and Y287 and LI290-291 as part of a common structure essential for receptor endocytosis and function. This new endocytosis motif, YxxLI, shares characteristics of tyrosine-based and dileucine-based internalization motifs and is highly conserved in IFN-γ Rs across species. The IFN-γ R1 270-LI-271 dileucine motif, previously thought to be involved in this receptor endocytosis, showed to be unnecessary for receptor endocytosis.

A polymorphism in TIM1 is associated with susceptibility to severe hepatitis A virus infection in humans.

During infection with the hepatitis A virus (HAV), most patients develop mild or asymptomatic disease. However, a small number of patients develop serious, life-threatening hepatitis. We investigated this variability in disease severity by examining 30 Argentinean patients with HAV-induced acute liver failure in a case-control, cross-sectional, observational study. We found that HAV-induced severe liver disease was associated with a 6-amino-acid insertion in TIM1/HAVCR1 (157insMTTTVP), the gene encoding the HAV receptor. This polymorphism was previously shown to be associated with protection against asthma and allergic diseases and with HIV progression. In binding assays, the TIM-1 protein containing the 157insMTTTVP insertion polymorphism bound HAV more efficiently. When expressed by human natural killer T (NKT) cells, this long form resulted in greater NKT cell cytolytic activity against HAV-infected liver cells, compared with the shorter TIM-1 protein without the polymorphism. To our knowledge, the 157insMTTTVP polymorphism in TIM1 is the first genetic susceptibility factor shown to predispose to HAV-induced acute liver failure. Furthermore, these results suggest that HAV infection has driven the natural selection of shorter forms of the TIM-1 protein, which binds HAV less efficiently, thereby protecting against severe HAV-induced disease, but which may predispose toward inflammation associated with asthma and allergy.

Bone marrow findings at diagnosis in patients with multisystem langerhans cell histiocytosis.

This study was designed to describe the bone marrow features of multisystem Langerhans cell histiocytosis (LCH) at diagnosis in patients with or without hematologic dysfunction. A retrospective review of bone marrow biopsies from patients with multisystem LCH was performed. Cases were diagnosed at the Garrahan Hospital between 1987 and 2004. Routine and immunohistochemistry techniques (hematoxylin-eosin, periodic acid-Schiff, Giemsa, Gomori reticulin, and CD1a, CD68, and CD61) were evaluated. Clinical outcome and laboratory data were obtained from the medical charts. Twenty-two bone marrow biopsies from patients with multisystem LCH were reviewed at onset of disease. Four patients had no hematologic dysfunction and the other 18 patients had monocytopenia (9), bicytopenia (7), or tricytopenia (2). Increased number and dysplasia of megakaryocytes were evident in 22/22 samples and emperipolesis was present in 21/22 (95%). Aggregates of histiocytes and hemophagocytosis were seen in 9/22 samples. Myelofibrosis was found in 16/17 (94%) evaluable samples at diagnosis. No association of myelofibrosis and cytopenias or clinical outcome was found. Positive CD1a confirmed the presence of LCH cells in 3/22 (14%) samples. Hemophagocytosis and poor outcome were significantly more common in patients with bilineage and trilineage cytopenias. Langerhans cell histiocytosis cells were rarely seen in the bone marrow of these patients (14%); increased histiocytes and hemophagocytosis were more commonly found (41%). Hemophagocytosis was associated with severe cytopenias. Bicytopenia and tricytopenia were associated with poor outcome (death). Myelofibrosis, megakaryocytic dysplasia, and emperipolesis were common findings.

Chronic granulomatous disease: complications and management.

Chronic granulomatous disease (CGD) is a genetically heterogenous primary immunodeficiency caused by defects in the nicotinamide adenine dinucleotide phosphate oxidase system. This metabolic pathway is responsible for the generation of reactive oxygen species during the respiratory burst, and is associated with germ killing and inflammatory reactions. CGD patients typically suffer from two types of clinical manifestation: recurrent bacterial and fungal infections, and dysregulated granulomata formation. Early diagnosis, antimicrobial prophylaxis and aggressive management of infectious complications are the cornerstones of CGD management. These three measures have strikingly improved the life expectancy and quality of life of CGD patients in the last 50 years. Very encouraging and promising results have been recently achieved, with definitive and curative options for this disease now available.

Clinical and molecular analysis of 49 patients with X-linked agammaglobulinemia from a single center in Argentina.

INTRODUCTION: Argentina has a large number of patients with definite diagnosis of X-linked agammaglobulinemia reported in the Latin-American registry. Forty-nine of them were seen in our referral pediatric hospital, between 1987 and 2005. RESULTS AND DISCUSSION: A retrospective study of clinical, laboratory, and molecular data showed that respiratory tract infections were the most frequent initial clinical presentation and the most common among all manifestations prior to diagnosis (69%). Up to diagnosis, we found a high frequency of severe infections (sepsis, 14% and meningitis, 16%) and a high proportion of patients with chronic lung disease. During follow-up, the development of chronic lung disease was significantly related with age at diagnosis and inappropriate treatment. CONCLUSION: Although molecular diagnosis has been available in our center for the past 10 years, there is no doubt that awareness for early recognition of immunodeficiency should be improved through broader and more comprehensive education programs emphasizing characteristics of patients with immunodeficiencies.

Disseminated Mycobacterium avium infection in a patient with a novel mutation in the interleukin-12 receptor-beta1 chain.

A girl with relapsing cervical lymphadenopathy due to Mycobacterium avium subsequently developed abdominal adenopathy and intestinal inflammation. 1 known (c.1623_1624delGCinsTT) and 1 novel mutation (c.65_68delCTGC of exon2) of the Interleukin-12 Receptor-beta1 (IL-12Rbeta1) gene was detected. Unlike reports of a more favorable outcome in these patients, our patient died of severe intestinal involvement.

Hepatitis A-associated macrophage activation syndrome in children with systemic juvenile idiopathic arthritis: report of 2 cases.

OBJECTIVE: We describe two 3-year-old patients with systemic juvenile idiopathic arthritis (SJIA) who developed hepatitis A-associated macrophage activation syndrome (MAS). One patient showed MAS as the presenting manifestation of SJIA, while MAS complicated SJIA during the second year of the disease course in the other child. Both girls presented with fever, jaundice, hepatosplenomegaly, neurological involvement, mucosal hemorrhage, and purpura. Cytopenias, hypofibrinogenemia, and hemophagocytosis confirmed the diagnosis. After aggressive treatment with high-dose corticosteroids and immunosuppressants one patient entered remission while the other one died. Hepatitis A virus may induce severe MAS in SJIA.

Defects in the interferon-gamma and interleukin-12 pathways.

The interferon-gamma (IFN-gamma)/interleukin-12 (IL-12) pathway is a pivotal player in the immune system and is central to controlling mycobacterial infections. We highlight the most recent and relevant advances in understanding this pathway and their repercussions on basic and clinical science. Human mutations in IFN-gamma receptor-1 (IFN-gammaR1), IFN-gammaR2, IL-12p40, IL-12 receptor-beta1, signal transducer and activator of transcription-1, and nuclear factor-kappaB essential modulator are analyzed in the context of genetic susceptibility to mycobacterial diseases. A diagnostic and therapeutic approach is described. The IFN-gamma/IL-12 pathway is central in immune control of both environmental and autochthonous challenges, as reflected in human mutations and animal models. Besides being crucial for mycobacterial control, the IFN-gamma/IL-12 pathway is also involved in the pathogenesis of autoimmune disease as well as tumor development and control. Genotype-phenotype correlations have been established for certain genes in this pathway, some of which have therapeutic implications.