Impact of newborn screening for SCID on the management of congenital athymia.

BACKGROUND: Newborn screening (NBS) programs for severe combined immunodeficiency facilitate early diagnosis of severe combined immunodeficiency and promote early treatment with hematopoietic stem cell transplantation, resulting in improved clinical outcomes. Infants with congenital athymia are also identified through NBS because of severe T-cell lymphopenia. With the expanding introduction of NBS programs, referrals of athymic patients for treatment with thymus transplantation have recently increased at Great Ormond Street Hospital (GOSH) (London, United Kingdom). OBJECTIVE: We studied the impact of NBS on timely diagnosis and treatment of athymic infants with thymus transplantation at GOSH. METHODS: We compared age at referral and complications between athymic infants diagnosed after clinical presentation (n = 25) and infants identified through NBS (n = 19) who were referred for thymus transplantation at GOSH between October 2019 and February 2023. We assessed whether age at time of treatment influences thymic output at 6 and 12 months after transplantation. RESULTS: The infants referred after identification through NBS were significantly younger and had fewer complications, in particular fewer infections. All deaths occurred in the group of those who did not undergo NBS, including 6 patients before and 2 after thymus transplantation because of preexisting infections. In the absence of significant comorbidities or diagnostic uncertainties, timely treatment was achieved more frequently after NBS. Treatment when younger than age 4 months was associated with higher thymic output at 6 and 12 months after transplantation. CONCLUSION: NBS contributes to earlier recognition of congenital athymia, promoting referral of athymic patients for thymus transplantation before they acquire infections or other complications and facilitating treatment at a younger age, thus playing an important role in improving their outcomes.

Hematopoietic Stem Cell Transplantation in ARPC1B Deficiency.

Mutations in the ARPC1B isoform component of human actin-related protein 2/3 complex have been recently associated with an inborn error of immunity characterized by combined immunodeficiency, allergies, autoinflammation, and platelet abnormalities. Currently, indications on the management of this novel disease and information on its outcome are lacking. We report the first case series of 7 children with a homozygous mutation in ARPC1B gene who underwent allogeneic-HSCT (allo-HSCT). All patients presented an early clinical onset, characterized by recurrent infections, failure to thrive and gastrointestinal bleeding episodes complicated with neonatal hemorrhagic enteritis in 3 cases, and macrophage activating syndrome in 2. Allo-HSCT was performed at the median age of 1.83 years after a myeloablative conditioning regimen in all cases. Engraftment occurred in all patients with full donor chimerism in 6 out of 7. The clinical course after engraftment was uneventful in 3 out of 7 children; 2 patients developed a grade 1-2 acute graft-versus-host disease (GvHD), and 1 patient a grade 1 chronic-GvHD. JC virus-related progressive multifocal leukoencephalopathy was diagnosed in one patient 13 months after haploidentical-HSCT and successfully managed with donor-derived viral-specific T-cell infusion. Only one patient had a fatal outcome 3 months after HSCT because of sepsis, after veno-occlusive disease, and transplant-associated microangiopathy. At a median follow-up of 19 months (range 3-110), 6 out of 7 patients are alive and disease-free. The severity of the clinical phenotype at diagnosis and the high survival rate, with limited transplant-related morbidity, strongly support the indication to allo-HSCT for patients with this diagnosis.

Lessons Learned From Five Years of Newborn Screening for Severe Combined Immunodeficiency in Israel.

BACKGROUND: Implementation of newborn screening (NBS) programs for severe combined immunodeficiency (SCID) have advanced the diagnosis and management of affected infants and undoubtedly improved their outcomes. Reporting long-term follow-up of such programs is of great importance. OBJECTIVE: We report a 5-year summary of the NBS program for SCID in Israel. METHODS: Immunologic and genetic assessments, clinical analyses, and outcome data from all infants who screened positive were evaluated and summarized. RESULTS: A total of 937,953 Guthrie cards were screened for SCID. A second Guthrie card was requested on 1,169 occasions (0.12%), which resulted in 142 referrals (0.015%) for further validation tests. Flow cytometry immune-phenotyping, T cell receptor excision circle measurement in peripheral blood, and expression of TCRVß repertoire for the validation of positive cases revealed a specificity and sensitivity of 93.7% and 75.9%, respectively, in detecting true cases of SCID. Altogether, 32 SCID and 110 non-SCID newborns were diagnosed, making the incidence of SCID in Israel as high as 1:29,000 births. The most common genetic defects in this group were associated with mutations in DNA cross-link repair protein 1C and IL-7 receptor α (IL-7Rα) genes. No infant with SCID was missed during the study time. Twenty-two SCID patients underwent hematopoietic stem cell transplantation, which resulted in a 91% survival rate. CONCLUSIONS: Newborn screening for SCID should ultimately be applied globally, specifically to areas with high rates of consanguineous marriages. Accumulating data from follow-up studies on NBS for SCID will improve diagnosis and treatment and enrich our understanding of immune development in health and disease.

Genetic workup as a complementary tool for the diagnosis of primary complement component deficiencies: a multicenter experience.

Diagnosis of primary complement deficiencies requires a high index of suspicion. Thus, susceptible patients are often underdiagnosed and untreated. Here, we present a multicenter experience with two novel inborn errors of the classical complement system. This is a retrospective multicenter analysis of computerized medical records of children (<18 years) admitted in the period between 2012 and 2018 at Shaare Zedek Medical Center in Jerusalem and Edmond and Lily Safra Children's Hospital, Tel-Hashomer Medical Center, in Ramat Gan, Israel. Patients were genetically diagnosed by a complementary immune workup. We identified 5 patients (3 males) from four different families harboring two novel mutations in the complement components C6-C8. Genetic mutations were identified by whole-exome sequencing or by sequencing of the coding exons of a single gene based on the findings in the immune workup. Clinical manifestations consisted of meningitis with or without meningococcemia. The immune workup demonstrated nearly absent levels of CH50, compatible with a complement pathway defect. Diagnosis delay ranged between 0 and 30 years. CONCLUSION: Awareness of risk factors for primary complement deficiencies, even at the first infectious episode, should facilitate prompt immune and genetic workup, commencing diagnosis and proper treatment for the patient and family. WHAT IS KNOWN: • Deficiencies in the classical terminal complement components increase susceptibility to invasive meningococcal infections. • Recurrent meningococcal infections mandate a diagnostic workup of the complement system. WHAT IS NEW: • Genetic workup can be utilized for prompt diagnosis of complement deficiencies. • High rates of consanguinity, even in the presence of a single meningococcal infection, should promote immune and genetic workups.

Peripheral Venous Catheter-related Bloodstream Infections in Hospitalized Children: The Role of Gram-negative Bacteria.

BACKGROUND: Peripheral venous catheter (PVC) is the most used vascular access device in medicine, allowing administration of intravenous fluids and medications. Known complications associated with PVC include extravasation, phlebitis and rarely bloodstream infection (BSI). Data regarding PVC-related BSI in children are lacking. Our aim was to evaluate the epidemiology, clinical and microbiologic characteristics of pediatric inpatients with PVC-related BSI. METHODS: A retrospective study was conducted in a pediatric tertiary care center. Children with BSI, admitted to general pediatric departments during 2010-2019, were identified and their medical records examined. Patients with BSI and phlebitis were further characterized and included in the analysis. We excluded patients with central venous catheters, other identified source of infection and with BSI upon admission. Data collected included patients' demographics and clinical and microbiologic characteristics. RESULTS: Twenty-seven children with PVC-related BSI were identified and included in the study, consisting of 0.2% of the total BSI cases. Patient's median age was 24 (range, 1.5-213) months, 14/27 (52%) were female and 6 (22%) were previously healthy while 21 (78%) had prior medical conditions. Sixteen (59.3%) patients had Gram-negative BSI and 6 (22.2%) Gram-positive bacteria. Polymicrobial infection occurred in 4 (14.8%) patients and Candida albicans in 1 (3.7%) patient. The most common isolated bacteria were Klebsiella spp and Staphylococcus aureus. Longer dwell-time was a predictor of Gram-negative bacteria. CONCLUSIONS: PVC-related BSI due to Gram-negative bacteria was more common than to Gram-positive bacteria. Clinicians should consider an initial broad-spectrum antibiotic coverage for PVC-related BSI in hospitalized pediatric patients.

SARS-CoV-2 Infection Among Health Care Workers Despite the Use of Surgical Masks and Physical Distancing-the Role of Airborne Transmission.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted mainly via respiratory droplets. A key question in the coronavirus disease 2019 pandemic is whether SARS-CoV-2 could be transmitted via the airborne route as well. We report for the first time SARS-CoV-2 nosocomial infections despite using surgical masks and physical distancing. This report may provide possible evidence for airborne transmission of SARS-CoV-2.

Efficacy of omalizumab treatment for pediatric chronic spontaneous urticaria: A multi-center retrospective case series.

BACKGROUND: Chronic urticaria is defined by the presence of itchy wheals, sometimes accompanied by angioedema, lasting for at least 6 weeks. In children, most cases occur without an eliciting factor and are defined as chronic spontaneous urticaria (CSU). CSU affects up to 0.75% of children with a negative impact on quality of life and school performance. CSU is treated in adults with second-generation antihistamines, increased up to four times normal doses for second-line treatment. Omalizumab (a monoclonal antibody to IgE) may be recommended as third-line therapy. A similar protocol is used in children, yet little is known of its efficacy and safety. OBJECTIVES: To summarize our multi-center experience in treating children with recalcitrant CSU with omalizumab. METHODS: A retrospective multi-center case series conducted in 5 tertiary care centers in Israel. Patients included were children <18 years old diagnosed with recalcitrant CSU who were treated with omalizumab. Patients were followed up throughout the duration of omalizumab therapy/symptom remission. Patients' electronic medical records were used to gather data. RESULTS: Nineteen participants (11 F; 8 M) presented with CSU between ages 6 and 16.9 years. Sixteen (84%) responded to omalizumab, including children <12 years old, although two became non-responsive after 6-12 months of therapy. Another three patients (16%) were resistant to treatment, achieving remission through fourth-line (Cyclosporine A) or other therapies. CONCLUSION: Children with recalcitrant CSU, even those <12 years old, respond well to standard-dose, third-line omalizumab therapy at rates similar to adults. Yet, some cases may become non-responsive with ongoing treatment.

Minor Clinical Impact of COVID-19 Pandemic on Patients With Primary Immunodeficiency in Israel.

In the last few months the world has witnessed a global pandemic due to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection causing coronavirus disease 2019 (COVID-19). Obviously, this pandemic affected individuals differently, with a significant impact on populations considered to be at high-risk. One such population, was assumed to be patients with primary genetic defect involving components or pathways of the immune system. While human immunity against COVID-19 is not fully understood, it is, so far, well documented, that both adaptive and innate cells have a critical role in protection against SARS-CoV-2. Here, we aimed to summarize the clinical and laboratory data on primary immunodeficiency (PID) patients in Israel, who were tested positive for SARS-CoV-2, in order to estimate the impact of COVID-19 on such patients. Data was collected from mid-February to end-September. During this time Israel experienced two "waves" of COVID-19 diseases; the first, from mid-February to mid-May and the second from mid-June and still ongoing at the end of data collection. A total of 20 PID patients, aged 4 months to 60 years, were tested positive for SARS-CoV-2, all but one, were detected during the second wave. Fourteen of the patients were on routine monthly IVIG replacement therapy at the time of virus detection. None of the patients displayed severe illness and none required hospitalization; moreover, 7/20 patients were completely asymptomatic. Possible explanations for the minimal clinical impact of COVID-19 pandemic observed in our PID patients include high level of awareness, extra-precautions, and even self-isolation. It is also possible that only specific immune pathways (e.g. type I interferon signaling), may increase the risk for a more severe course of disease and these are not affected in many of the PID patients. In some cases, lack of an immune response actually may be a protective measure against the development of COVID-19 sequelae.

A Large Cohort of RAG1/2-Deficient SCID Patients-Clinical, Immunological, and Prognostic Analysis.

INTRODUCTION: Severe combined immunodeficiency (SCID) is a fatal disorder resulting from various genetic defects. In the Middle East, where consanguineous marriage is prevalent, autosomal recessive mutations in recombination-activating genes (RAG) are a leading cause of SCID. We present a large cohort of SCID patients due to RAG1 or RAG2 mutations. METHODS: Twenty-six patients with RAG1 or RAG2 deficiency, diagnosed at Sheba Medical Center, were retrospectively investigated. Clinical presentation, immunologic phenotype, genetic analysis, treatment, and outcome were analyzed. RESULTS: Majority of patients were referred from the Palestinian Authority. Most patients were males of Muslim Arab descent, 77% were born to consanguineous parents, and 65% had family history of immunodeficiency. Nearly all patients suffered from various infections before turning 2 months old, eight patients (31%) presented with Omenn and Omenn-like syndrome, and three patients (11%) had maternal engraftment. Notably, seven patients (27%) suffered from vaccine-derived infections, including a rare case of measles encephalitis. Nineteen patients underwent hematopoietic stem cell transplantation (HSCT) at a median age of 6 months, with a successful outcome for 72% of them. Genetic analysis revealed 11 different mutations (7 RAG2, 4 RAG1), two of them novel. CONCLUSIONS: Consanguineous marriages account for a genetic "founder effect." SCID is a pediatric emergency that dictates immediate precautions and curative treatment with HSCT. Due to lack of newborn screening for SCID within the Palestinian population, most patients in this cohort were diagnosed upon clinical symptoms, which led to a delayed diagnosis, harmful administration of contra-indicated live vaccines, delay in HSCT, and poor outcome.

Lentiviral gene therapy corrects platelet phenotype and function in patients with Wiskott-Aldrich syndrome.

BACKGROUND: Thrombocytopenia is a serious issue for all patients with classical Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) because it causes severe and life-threatening bleeding. Lentiviral gene therapy (GT) for WAS has shown promising results in terms of immune reconstitution. However, despite the reduced severity and frequency of bleeding events, platelet counts remain low in GT-treated patients. OBJECTIVE: We carefully investigated platelet defects in terms of phenotype and function in untreated patients with WAS and assessed the effect of GT treatment on platelet dysfunction. METHODS: We analyzed a cohort of 20 patients with WAS/XLT, 15 of them receiving GT. Platelet phenotype and function were analyzed by using electron microscopy, flow cytometry, and an aggregation assay. Platelet protein composition was assessed before and after GT by means of proteomic profile analysis. RESULTS: We show that platelets from untreated patients with WAS have reduced size, abnormal ultrastructure, and a hyperactivated phenotype at steady state, whereas activation and aggregation responses to agonists are decreased. GT restores platelet size and function early after treatment and reduces the hyperactivated phenotype proportionally to WAS protein expression and length of follow-up. CONCLUSIONS: Our study highlights the coexistence of morphologic and multiple functional defects in platelets lacking WAS protein and demonstrates that GT normalizes the platelet proteomic profile with consequent restoration of platelet ultrastructure and phenotype, which might explain the observed reduction of bleeding episodes after GT. These results are instrumental also from the perspective of a future clinical trial in patients with XLT only presenting with microthrombocytopenia.

T-cell defects in patients with ARPC1B germline mutations account for combined immunodeficiency.

ARPC1B is a key factor for the assembly and maintenance of the ARP2/3 complex that is involved in actin branching from an existing filament. Germline biallelic mutations in ARPC1B have been recently described in 6 patients with clinical features of combined immunodeficiency (CID), whose neutrophils and platelets but not T lymphocytes were studied. We hypothesized that ARPC1B deficiency may also lead to cytoskeleton and functional defects in T cells. We have identified biallelic mutations in ARPC1B in 6 unrelated patients with early onset disease characterized by severe infections, autoimmune manifestations, and thrombocytopenia. Immunological features included T-cell lymphopenia, low numbers of naïve T cells, and hyper-immunoglobulin E. Alteration in ARPC1B protein structure led to absent/low expression by flow cytometry and confocal microscopy. This molecular defect was associated with the inability of patient-derived T cells to extend an actin-rich lamellipodia upon T-cell receptor (TCR) stimulation and to assemble an immunological synapse. ARPC1B-deficient T cells additionally displayed impaired TCR-mediated proliferation and SDF1-α-directed migration. Gene transfer of ARPC1B in patients' T cells using a lentiviral vector restored both ARPC1B expression and T-cell proliferation in vitro. In 2 of the patients, in vivo somatic reversion restored ARPC1B expression in a fraction of lymphocytes and was associated with a skewed TCR repertoire. In 1 revertant patient, memory CD8+ T cells expressing normal levels of ARPC1B displayed improved T-cell migration. Inherited ARPC1B deficiency therefore alters T-cell cytoskeletal dynamics and functions, contributing to the clinical features of CID.

MHC II deficient infant identified by newborn screening program for SCID.

Newborn screening (NBS) programs for severe combined immunodeficiency (SCID), using the TREC-based assay, have enabled early diagnosis, prompt treatment, and eventually changed the natural history of affected infants. Nevertheless, it was believed that some affected infants with residual T cell, such as patients with MHC II deficiency, will be misdiagnosed by this assay. A full immune workup and genetic analysis using direct Sanger sequencing and whole exome sequencing have been performed to a patient that was identified by the Israeli NBS program for SCID. The patient was found to have severe CD4 lymphopenia with an inverted CD4/CD8 ratio, low TREC levels in peripheral blood, abnormal response to mitogen stimulation, and a skewed T cell receptor repertoire. HLA-DR expression on peripheral blood lymphocytes was undetectable suggesting a diagnosis of MHC II deficiency. Direct sequencing of the RFX5 gene revealed a stop codon change (p. R239X, c. C715T), which could cause the patient's immune phenotype. His parents were found to be heterozygote carriers for the mutation. Whole exome sequencing could not identify other potential mutations to explain his immunodeficiency. The patient underwent successful conditioned hematopoietic stem cell transplantation from healthy matched unrelated donor and is currently well and alive with full chimerism. Infants with MHC class II deficiency can potentially be identified by the TREC-based assay NBS for SCID. Therefore, MHC II molecules (e.g., HLA-DR) measurement should be part of the confirmatory immune-phenotyping for patients with positive screening results. This will make the diagnosis of such patients straightforward.

De Novo Allergy and Immune-Mediated Disorders Following Solid-Organ Transplantation-Prevalence, Natural History, and Risk Factors.

OBJECTIVES: To describe the prevalence, natural course, outcome, and risk factors of post-transplant de novo allergy and autoimmunity. STUDY DESIGN: A cross-sectional, cohort study of all children (<18 years) who underwent a solid-organ transplantation, between 2000 and 2012, in a single transplant center, with a follow-up period of 6 months or more post-transplant and without history of allergy or immune-mediated disorder pretransplant. RESULTS: A total of 626 eligible patients were screened, and 273 patients (160 males; 59%) met the inclusion criteria; this included 111 liver, 103 heart, 52 kidney, and 7 multivisceral recipients. Patients were followed for a median period of 3.6 years. A total of 92 (34%) patients (42 males, 46%) developed allergy or autoimmune disease after transplantation, with a high prevalence among liver (41%), heart (40%), and multivisceral (57%) transplant recipients compared with kidney recipients (4%; P < .001). Post-transplant allergies included eczema (n = 44), food allergy (22), eosinophilic gastrointestinal disease (11), and asthma (28). Autoimmunity occurred in 18 (6.6%) patients, presenting mainly as autoimmune cytopenia (n = 10). In a multivariate analysis, female sex, young age at transplantation, family history of allergy, Epstein-Barr virus infection, and elevated eosinophil count >6 months post-transplantation were associated with an increased risk for allergy or autoimmunity. Two patients (0.7%) died from autoimmune hemolytic anemia and hemophagocytic lymphohistiocytosis, and 52 episodes of post-transplant allergy, autoimmunity, and immune-mediated disorders (37%) did not improve over time. CONCLUSIONS: Allergy and autoimmunity are common in pediatric liver, heart, and multivisceral transplant recipients and pose a significant health burden. Further studies are required to clarify the mechanisms behind this post-transplant immune dysregulation.

Successful Intravenous Immunoglobulin Treatment in Pediatric Severe DRESS Syndrome.

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare, potentially life-threatening delayed drug-induced hypersensitivity reaction. The most frequently reported drugs causing DRESS are aromatic antiepileptic agents. Prompt withdrawal of the offending drug and administering systemic corticosteroids is the most widely accepted and used treatment. The treatment of severe DRESS not responsive to systemic corticosteroids is uncertain. OBJECTIVE: The objective of this study was to describe a case series of pediatric patients with DRESS who were treated successfully with intravenous immunoglobulins (IVIGs). METHODS: A retrospective review of all children hospitalized in a tertiary care children's hospital with severe DRESS syndrome who received IVIG in addition to offending drug withdrawal and systemic corticosteroids during 1999-2017 is performed. RESULTS: Seven severe DRESS patients (4 males, age: 9.5 ± 5.7 years) are described. The offending drugs were antiepileptics in all but one case. Clinical findings included fever, rash, lymphadenopathy, dyspnea, anasarca, and hepatic involvement. After IVIG treatment (total dosage: 1-2 g/kg), fever resolved within a median time of 1 (range, 0-5) day, rash disappeared after 6.3 ± 1.6 days, and liver enzymes substantially improved after 3.8 ± 1.6 days. Patients were discharged 6.1 ± 2.7 days after IVIG commencement. There was no mortality. CONCLUSION: The addition of IVIG in DRESS syndrome resistant to regular drug withdrawal and systemic corticosteroid therapy may hasten disease recovery.

First Year of Israeli Newborn Screening for Severe Combined Immunodeficiency-Clinical Achievements and Insights.

Severe combined immunodeficiency (SCID), the most severe form of T cell immunodeficiency, is detectable through quantification of T cell receptor excision circles (TRECs) in dried blood spots obtained at birth. Herein, we describe the results of the first year of the Israeli SCID newborn screening (NBS) program. This important, life-saving screening test is available at no cost for every newborn in Israel. Eight SCID patients were diagnosed through the NBS program in its first year, revealing an incidence of 1:22,500 births in the Israeli population. Consanguine marriages and Muslim ethnic origin were found to be a risk factor in affected newborns, and a founder effect was detected for both IL7Rα and DCLRE1C deficiency SCID. Lymphocyte subset analysis and TREC quantification in the peripheral blood appear to be sufficient for confirmation of typical and leaky SCID and ruling out false positive (FP) results. Detection of secondary targets (infants with non-SCID lymphopenia) did not significantly affect the management or outcomes of these infants in our cohort. In the general, non-immunodeficient population, TREC rises along with gestational age and birth weight, and is significantly higher in females and the firstborn of twin pairs. Low TREC correlates with both gestational age and birth weight in extremely premature newborns. Additionally, the rate of TREC increase per week consistently accelerates with gestational age. Together, these findings mandate a lower cutoff or a more lenient screening algorithm for extremely premature infants, in order to reduce the high rate of FPs within this group. A significant surge in TREC values was observed between 28 and 30 weeks of gestation, where median TREC copy numbers rise by 50% over 2 weeks. These findings suggest a maturational step in T cell development around week 29 gestation, and imply moderate to late preterms should be screened with the same cutoff as term infants. The SCID NBS program is still in its infancy, but is already bearing fruit in the early detection and improved outcomes of children with SCID in Israel and other countries.

Disruption of Thrombocyte and T Lymphocyte Development by a Mutation in ARPC1B.

Regulation of the actin cytoskeleton is crucial for normal development and function of the immune system, as evidenced by the severe immune abnormalities exhibited by patients bearing inactivating mutations in the Wiskott-Aldrich syndrome protein (WASP), a key regulator of actin dynamics. WASP exerts its effects on actin dynamics through a multisubunit complex termed Arp2/3. Despite the critical role played by Arp2/3 as an effector of WASP-mediated control over actin polymerization, mutations in protein components of the Arp2/3 complex had not previously been identified as a cause of immunodeficiency. Here, we describe two brothers with hematopoietic and immunologic symptoms reminiscent of Wiskott-Aldrich syndrome (WAS). However, these patients lacked mutations in any of the genes previously associated with WAS. Whole-exome sequencing revealed a homozygous 2 bp deletion, n.c.G623DEL-TC (p.V208VfsX20), in Arp2/3 complex component ARPC1B that causes a frame shift resulting in premature termination. Modeling of the disease in zebrafish revealed that ARPC1B plays a critical role in supporting T cell and thrombocyte development. Moreover, the defects in development caused by ARPC1B loss could be rescued by the intact human ARPC1B ortholog, but not by the p.V208VfsX20 variant identified in the patients. Moreover, we found that the expression of ARPC1B is restricted to hematopoietic cells, potentially explaining why a mutation in ARPC1B has now been observed as a cause of WAS, whereas mutations in other, more widely expressed, components of the Arp2/3 complex have not been observed.

Chronic granulomatous disease: Clinical, functional, molecular, and genetic studies. The Israeli experience with 84 patients.

Chronic granulomatous disease (CGD) is an innate immunodeficiency with a genetic defect of the nicotinamide adenosine dinucleotide phosphate, reduced, oxidase components. This leads to decreased reactive oxygen species (ROS) production, which renders patients susceptible to life-threatening infections. Over the course of 30 years, we diagnosed CGD in 84 patients from 61 families using functional, molecular, and genetic studies. The incidence of CGD in Israel is 1.05 per 100,000 live-births in the Jewish population and 1.49 in the Israeli Arab population. We diagnosed 52 patients (62%) with autosomal recessive inheritance (AR-CGD) and 32 (38%) with X-linked recessive inheritance (XLR-CGD). Consanguinity was detected in 64% of AR-CGD families (14% in Jews and 50% in Israeli Arabs). We found 36 different mutations (23 in XLR-CGD and 13 in AR-CGD patients), 15 of which were new. The clinical spectrum of CGD varied from mild to severe disease in both XLR and AR forms, although the AR subtype is generally milder. Further, residual ROS production correlated with milder clinical expression, better prognosis and improved overall survival. Patients with recurrent pyogenic infections developed fibrosis and hyperinflammatory states with granuloma formation. The management of CGD has progressed substantially in recent years, evolving from a fatal disease of early childhood to one of long-term survival. Our present cohort displays an encouraging 81% overall long term survival. Early hematopoietic stem cell transplantation is advisable before tissue damage is irreversible. Successful transplantation was performed in 18/21 patients. Therapeutic gene modification could become an alternative cure for CGD. Am. J. Hematol. 92:28-36, 2017. © 2016 Wiley Periodicals, Inc.