Role of IL-27 in Epstein-Barr virus infection revealed by IL-27RA deficiency.

Epstein-Barr virus (EBV) infection can engender severe B cell lymphoproliferative diseases1,2. The primary infection is often asymptomatic or causes infectious mononucleosis (IM), a self-limiting lymphoproliferative disorder3. Selective vulnerability to EBV has been reported in association with inherited mutations impairing T cell immunity to EBV4. Here we report biallelic loss-of-function variants in IL27RA that underlie an acute and severe primary EBV infection with a nevertheless favourable outcome requiring a minimal treatment. One mutant allele (rs201107107) was enriched in the Finnish population (minor allele frequency = 0.0068) and carried a high risk of severe infectious mononucleosis when homozygous. IL27RA encodes the IL-27 receptor alpha subunit5,6. In the absence of IL-27RA, phosphorylation of STAT1 and STAT3 by IL-27 is abolished in T cells. In in vitro studies, IL-27 exerts a synergistic effect on T-cell-receptor-dependent T cell proliferation7 that is deficient in cells from the patients, leading to impaired expansion of potent anti-EBV effector cytotoxic CD8+ T cells. IL-27 is produced by EBV-infected B lymphocytes and an IL-27RA-IL-27 autocrine loop is required for the maintenance of EBV-transformed B cells. This potentially explains the eventual favourable outcome of the EBV-induced viral disease in patients with IL-27RA deficiency. Furthermore, we identified neutralizing anti-IL-27 autoantibodies in most individuals who developed sporadic infectious mononucleosis and chronic EBV infection. These results demonstrate the critical role of IL-27RA-IL-27 in immunity to EBV, but also the hijacking of this defence by EBV to promote the expansion of infected transformed B cells.

Late-onset enteric virus infection associated with hepatitis (EVAH) in transplanted SCID patients.

BACKGROUND: Allogenic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT) are potentially curative treatments for severe combined immunodeficiency (SCID). Late-onset posttreatment manifestations (such as persistent hepatitis) are not uncommon. OBJECTIVE: We sought to characterize the prevalence and pathophysiology of persistent hepatitis in transplanted SCID patients (SCIDH+) and to evaluate risk factors and treatments. METHODS: We used various techniques (including pathology assessments, metagenomics, single-cell transcriptomics, and cytometry by time of flight) to perform an in-depth study of different tissues from patients in the SCIDH+ group and corresponding asymptomatic similarly transplanted SCID patients without hepatitis (SCIDH-). RESULTS: Eleven patients developed persistent hepatitis (median of 6 years after HSCT or GT). This condition was associated with the chronic detection of enteric viruses (human Aichi virus, norovirus, and sapovirus) in liver and/or stools, which were not found in stools from the SCIDH- group (n = 12). Multiomics analysis identified an expansion of effector memory CD8+ T cells with high type I and II interferon signatures. Hepatitis was associated with absence of myeloablation during conditioning, split chimerism, and defective B-cell function, representing 25% of the 44 patients with SCID having these characteristics. Partially myeloablative retransplantation or GT of patients with this condition (which we have named as "enteric virus infection associated with hepatitis") led to the reconstitution of T- and B-cell immunity and remission of hepatitis in 5 patients, concomitantly with viral clearance. CONCLUSIONS: Enteric virus infection associated with hepatitis is related to chronic enteric viral infection and immune dysregulation and is an important risk for transplanted SCID patients with defective B-cell function.

Longitudinal Assessment of Preterm Infants Treated with Erythropoiesis Stimulating Agents.

OBJECTIVE: We previously reported improved neurodevelopment at 2 and 4 years among preterm infants treated with erythropoietin or darbepoetin, known as erythropoiesis-stimulating agents (ESAs). We now characterize longitudinal outcomes through 6 years. METHODS: Children randomized to ESAs or placebo were evaluated at 6 years. Healthy-term children served as controls. Tests of cognition and executive function (EF) were performed. RESULTS: Cognitive/EF scores remained similar between 4 and 6 years within each group (ESA: 43 children; placebo: 17 children; term: 21 children). ESA recipients scored higher than placebo on Full-Scale IQ (94.2 ± 18.6 vs. 81.6 ± 16.7, p = 0.022), and Performance IQ (97.3 ± 16.2 vs. 81.7 ± 15.2, = 0.005). Aggregate EF trended better for the ESA group. Term controls scored better than placebo on all measures. ESA and term controls scored similarly on cognitive and EF tests. CONCLUSION: ESA recipients had better outcomes than placebo recipients, and were similar to term children. ESAs may improve long-term cognition and executive function in preterm infants.

Anxiety symptoms and associated functional impairment in children with CHD in a neurodevelopmental follow-up clinic.

OBJECTIVES: To examine the prevalence of anxiety symptoms and associated functional impairment to adaptive skills among elementary-aged children with CHD and to determine the need for anxiety screening in this high-risk population. STUDY DESIGN: In a single-centre retrospective, cohort design, caregivers reported anxiety symptoms using Conner's scales and functional impairment to adaptive skills using the Adaptive Behavior Assessment System. A total of 194 children were stratified across two cohorts: early elementary (ages 3-6 years) and late elementary (ages 6-14 years). Descriptive statistics summarised the frequency of anxiety symptoms and functional impairment. Spearman's correlations compared anxiety symptoms to functional impairment of adaptive functioning. Univariable logistic regressions examined demographic and clinical characteristics associated with anxiety symptoms. RESULTS: The majority of patients presented with anxiety, early elementary (63%), and late elementary cohorts (78%). Functional impairment was moderately correlated with anxiety symptoms in the early elementary cohort (rs = -.42, 95% CI [-0.58, -0.21], p = <.001). Greater anxiety symptoms were associated with lower cardiac complexity at primary age of surgery in the late elementary cohort (OR = 12.15, p = 0.019). Lesser anxiety symptoms were associated with having private insurance (OR = 0.25, p = 0.014). CONCLUSION: This study demonstrates anxiety symptoms are common and associated with functional impairment to adaptive functioning in younger children with CHD. No clear clinical predictors exist for anxiety symptoms or functional impairment; therefore, screening for anxiety symptoms may need to be added to standard clinical assessment of all children with CHD participating in neurodevelopmental follow-up.

Hydrocortisone to Improve Survival without Bronchopulmonary Dysplasia.

BACKGROUND: Bronchopulmonary dysplasia is a prevalent complication after extremely preterm birth. Inflammation with mechanical ventilation may contribute to its development. Whether hydrocortisone treatment after the second postnatal week can improve survival without bronchopulmonary dysplasia and without adverse neurodevelopmental effects is unknown. METHODS: We conducted a trial involving infants who had a gestational age of less than 30 weeks and who had been intubated for at least 7 days at 14 to 28 days. Infants were randomly assigned to receive either hydrocortisone (4 mg per kilogram of body weight per day tapered over a period of 10 days) or placebo. Mandatory extubation thresholds were specified. The primary efficacy outcome was survival without moderate or severe bronchopulmonary dysplasia at 36 weeks of postmenstrual age, and the primary safety outcome was survival without moderate or severe neurodevelopmental impairment at 22 to 26 months of corrected age. RESULTS: We enrolled 800 infants (mean [±SD] birth weight, 715±167 g; mean gestational age, 24.9±1.5 weeks). Survival without moderate or severe bronchopulmonary dysplasia at 36 weeks occurred in 66 of 398 infants (16.6%) in the hydrocortisone group and in 53 of 402 (13.2%) in the placebo group (adjusted rate ratio, 1.27; 95% confidence interval [CI], 0.93 to 1.74). Two-year outcomes were known for 91.0% of the infants. Survival without moderate or severe neurodevelopmental impairment occurred in 132 of 358 infants (36.9%) in the hydrocortisone group and in 134 of 359 (37.3%) in the placebo group (adjusted rate ratio, 0.98; 95% CI, 0.81 to 1.18). Hypertension that was treated with medication occurred more frequently with hydrocortisone than with placebo (4.3% vs. 1.0%). Other adverse events were similar in the two groups. CONCLUSIONS: In this trial involving preterm infants, hydrocortisone treatment starting on postnatal day 14 to 28 did not result in substantially higher survival without moderate or severe bronchopulmonary dysplasia than placebo. Survival without moderate or severe neurodevelopmental impairment did not differ substantially between the two groups. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT01353313.).

Mortality, In-Hospital Morbidity, Care Practices, and 2-Year Outcomes for Extremely Preterm Infants in the US, 2013-2018.

IMPORTANCE: Despite improvement during recent decades, extremely preterm infants continue to contribute disproportionately to neonatal mortality and childhood morbidity. OBJECTIVE: To review survival, in-hospital morbidities, care practices, and neurodevelopmental and functional outcomes at 22-26 months' corrected age for extremely preterm infants. DESIGN, SETTING, AND PARTICIPANTS: Prospective registry for extremely preterm infants born at 19 US academic centers that are part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. The study included 10 877 infants born at 22-28 weeks' gestational age between January 1, 2013, and December 31, 2018, including 2566 infants born before 27 weeks between January 1, 2013, and December 31, 2016, who completed follow-up assessments at 22-26 months' corrected age. The last assessment was completed on August 13, 2019. Outcomes were compared with a similar cohort of infants born in 2008-2012 adjusting for gestational age. EXPOSURES: Extremely preterm birth. MAIN OUTCOMES AND MEASURES: Survival and 12 in-hospital morbidities were assessed, including necrotizing enterocolitis, infection, intracranial hemorrhage, retinopathy of prematurity, and bronchopulmonary dysplasia. Infants were assessed at 22-26 months' corrected age for 12 health and functional outcomes, including neurodevelopment, cerebral palsy, vision, hearing, rehospitalizations, and need for assistive devices. RESULTS: The 10 877 infants were 49.0% female and 51.0% male; 78.3% (8495/10848) survived to discharge, an increase from 76.0% in 2008-2012 (adjusted difference, 2.0%; 95% CI, 1.0%-2.9%). Survival to discharge was 10.9% (60/549) for live-born infants at 22 weeks and 94.0% (2267/2412) at 28 weeks. Survival among actively treated infants was 30.0% (60/200) at 22 weeks and 55.8% (535/958) at 23 weeks. All in-hospital morbidities were more likely among infants born at earlier gestational ages. Overall, 8.9% (890/9956) of infants had necrotizing enterocolitis, 2.4% (238/9957) had early-onset infection, 19.9% (1911/9610) had late-onset infection, 14.3% (1386/9705) had severe intracranial hemorrhage, 12.8% (1099/8585) had severe retinopathy of prematurity, and 8.0% (666/8305) had severe bronchopulmonary dysplasia. Among 2930 surviving infants with gestational ages of 22-26 weeks eligible for follow-up, 2566 (87.6%) were examined. By 2-year follow-up, 8.4% (214/2555) of children had moderate to severe cerebral palsy, 1.5% (38/2555) had bilateral blindness, 2.5% (64/2527) required hearing aids or cochlear implants, 49.9% (1277/2561) had been rehospitalized, and 15.4% (393/2560) required mobility aids or other supportive devices. Among 2458 fully evaluated infants, 48.7% (1198/2458) had no or mild neurodevelopmental impairment at follow-up, 29.3% (709/2419) had moderate neurodevelopmental impairment, and 21.2% (512/2419) had severe neurodevelopmental impairment. CONCLUSIONS AND RELEVANCE: Among extremely preterm infants born in 2013-2018 and treated at 19 US academic medical centers, 78.3% survived to discharge, a significantly higher rate than for infants born in 2008-2012. Among infants born at less than 27 weeks' gestational age, rehospitalization and neurodevelopmental impairment were common at 2 years of age.

Somatic reversion of pathogenic DOCK8 variants alters lymphocyte differentiation and function to effectively cure DOCK8 deficiency.

Inborn errors of immunity cause monogenic immune dysregulatory conditions such as severe and recurrent pathogen infection, inflammation, allergy, and malignancy. Somatic reversion refers to the spontaneous repair of a pathogenic germline genetic variant and has been reported to occur in a number of inborn errors of immunity, with a range of impacts on clinical outcomes of these conditions. DOCK8 deficiency due to biallelic inactivating mutations in DOCK8 causes a combined immunodeficiency characterized by severe bacterial, viral, and fungal infections, as well as allergic disease and some cancers. Here, we describe the clinical, genetic, and cellular features of 3 patients with biallelic DOCK8 variants who, following somatic reversion in multiple lymphocyte subsets, exhibited improved clinical features, including complete resolution of infection and allergic disease, and cure over time. Acquisition of DOCK8 expression restored defective lymphocyte signalling, survival and proliferation, as well as CD8+ T cell cytotoxicity, CD4+ T cell cytokine production, and memory B cell generation compared with typical DOCK8-deficient patients. Our temporal analysis of DOCK8-revertant and DOCK8-deficient cells within the same individual established mechanisms of clinical improvement in these patients following somatic reversion and revealed further nonredundant functions of DOCK8 in human lymphocyte biology. Last, our findings have significant implications for future therapeutic options for the treatment of DOCK8 deficiency.

Rapid identification and characterization of infected cells in blood during chronic active Epstein-Barr virus infection.

Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.

Donor-targeted serotherapy as a rescue therapy for steroid-resistant acute GVHD after HLA-mismatched kidney transplantation.

Acute graft-versus-host disease (GVHD) is a rare but frequently lethal complication after solid organ transplantation. GVHD occurs in unduly immunocompromised hosts but requires the escalation of immunosuppression, which does not discriminate between host and donor cells. In contrast, donor-targeted therapy would ideally mitigate graft-versus-host reactivity while sparing recipient immune functions. We report two children with end-stage renal disease and severe primary immune deficiency (Schimke syndrome) who developed severe steroid-resistant acute GVHD along with full and sustained donor T cell chimerism after isolated kidney transplantation. Facing a therapeutic dead end, we used a novel strategy based on the adoptive transfer of anti-HLA donor-specific antibodies (DSAs) through the transfusion of highly selected plasma. After approval by the appropriate regulatory authority, an urgent nationwide search was launched among more than 3800 registered blood donors with known anti-HLA sensitization. Adoptively transferred DSAs bound to and selectively depleted circulating donor T cells. The administration of DSA-rich plasma was well tolerated and notably did not induce antibody-mediated rejection of the renal allografts. Acute GVHD symptoms promptly resolved in one child. This report provides a proof of concept for a highly targeted novel therapeutic approach for solid organ transplantation-associated GVHD.

The Benefits and Bias in Neurodevelopmental Evaluation for Children with Congenital Heart Disease.

Neurodevelopmental (ND) impairment is common in children with congenital heart disease (CHD). While routine ND surveillance and evaluation of high-risk patients has become the standard-of-care, capture rate, barriers to referral, and potential patient benefits remain incompletely understood. Electronic data warehouse records from a single center were reviewed to identify all eligible and evaluated patients between July 2015 and December 2017 based on current guidelines for ND screening in CHD. Diagnoses, referring provider, and payor were considered. Potential benefit of the evaluation was defined as receipt of new diagnosis, referral for additional evaluation, or referral for a new service. Contingencies were assessed with Fisher's exact test. In this retrospective, cohort study, of 3434 children identified as eligible for ND evaluation, 135 were evaluated (4%). Appropriate evaluation was affected by diagnostic bias against coarctation of the aorta (CoArc) and favoring hypoplastic left heart syndrome (HLHS) (1.8 vs. 11.9%, p<0.01). Referrals were disproportionally made by a select group of cardiologists, and the rate of ND appointment non-compliance was higher in self-pay compared to insured patients (78% vs 27%, p<0.01). Potential benefit rate was 70-80% amongst individuals with the three most common diagnoses requiring neonatal surgery (CoArc, transposition of the great arteries, and HLHS). Appropriate ND evaluation in CHD is impacted by diagnosis, provider, and insurance status. Potential benefit of ND evaluation is high regardless of diagnosis. Strategies to improve access to ND evaluations and provider understanding of the at-risk population will likely improve longitudinal ND surveillance and clinical benefit.

Concomitant PIK3CD and TNFRSF9 deficiencies cause chronic active Epstein-Barr virus infection of T cells.

Infection of T cells by Epstein-Barr virus (EBV) causes chronic active EBV infection (CAEBV) characterized by T cell lymphoproliferative disorders (T-LPD) of unclear etiology. Here, we identified two homozygous biallelic loss-of-function mutations in PIK3CD and TNFRSF9 in a patient who developed a fatal CAEBV. The mutation in TNFRSF9 gene coding CD137/4-1BB, a costimulatory molecule expressed by antigen-specific activated T cells, resulted in a complete loss of CD137 expression and impaired T cell expansion toward CD137 ligand-expressing cells. Isolated as observed in one sibling, CD137 deficiency resulted in persistent EBV-infected T cells but without clinical manifestations. The mutation in PIK3CD gene that encodes the catalytic subunit p110δ of the PI3K significantly reduced its kinase activity. Deficient T cells for PIK3CD exhibited reduced AKT signaling, while calcium flux, RAS-MAPK activation, and proliferation were increased, suggestive of an imbalance between the PLCγ1 and PI3K pathways. These skewed signals in T cells may sustain accumulation of EBV-infected T cells, a process controlled by the CD137-CD137L pathway, highlighting its critical role in immunity to EBV.

Precocious and Early Central Puberty in Children With Pre-existing Medical Conditions: A Single Center Study.

Background: Precocious and early puberty are reported findings in children with pre-existing medical conditions including certain syndromes. Series pertaining to such situations are limited. Methods: A retrospective, single-center study was conducted on children with central precocious puberty (onset before the age of 8 years in girls and 9 years in boys) or early puberty (onset between 8 and 9 years in girls and between 9 and 10.5 years in boys) diagnosed on the background of a known pre-existing chronic significant medical condition. Patients with a CNS tumor and those exposed to cranial irradiation were excluded. Results: Precocious puberty was diagnosed in 13 patients and early puberty in 12. Mean age at onset of puberty was 6.65 ± 2.3 years in girls (n = 15) and 9.4 ± 0.84 years in boys (n = 10). The most common disorders were psychomotor delay (n = 12), psychiatric disorders (n = 7) and/or epilepsy (n = 5). Precocious or early puberty was among the symptoms experienced by patients with a variety of syndromes including lipofuscinosis (2 siblings), Dravet syndrome and Silver-Russel syndrome. Pituitary stalk interruption with agenesis of olfactory bulbs and optic nerve atrophy was found on imaging in one patient who presented with blindness, epilepsy, and autism spectrum disorder. The other diseases associated with precocious or early puberty are adrenocorticotropic deficiency, dyspraxia and bone abnormalities, glomerulopathy with complete renal failure, and repeated intra-fetal deaths in the mother. Karyotype analysis revealed chromosomal duplication (chromosome 15 in 2 cases; chromosomes 17 and 11 in one case each) in 4 of 8 patients evaluated. Conclusions: Data from patients with complex disease who experience precocious or early puberty may provide clues regarding the genetic determinants of pubertal development.

Inherited Immunodeficiencies With High Predisposition to Epstein-Barr Virus-Driven Lymphoproliferative Diseases.

Epstein-Barr Virus (EBV) is a gamma-herpes virus that infects 90% of humans without any symptoms in most cases, but has an oncogenic potential, especially in immunocompromised individuals. In the past 30 years, several primary immunodeficiencies (PIDs) associated with a high risk to develop EBV-associated lymphoproliferative disorders (LPDs), essentially consisting of virus-associated hemophagocytic syndrome, non-malignant and malignant B-cell LPDs including non-Hodgkin and Hodgkin's types of B lymphomas have been characterized. Among them are SH2D1A (SAP), XIAP, ITK, MAGT1, CD27, CD70, CTPS1, RASGRP1, and CORO1A deficiencies. Penetrance of EBV infection ranges from 50 to 100% in those PIDs. Description of large cohorts and case reports has refined the specific phenotypes associated with these PIDs helping to the diagnosis. Specific pathways required for protective immunity to EBV have emerged from studies of these PIDs. SLAM-associated protein-dependent SLAM receptors and MAGT1-dependent NKG2D pathways are important for T and NK-cell cytotoxicity toward EBV-infected B-cells, while CD27-CD70 interactions are critical to drive the expansion of EBV-specific T-cells. CTPS1 and RASGRP1 deficiencies further strengthen that T-lymphocyte expansion is a key step in the immune response to EBV. These pathways appear to be also important for the anti-tumoral immune surveillance of abnormal B cells. Monogenic PIDs should be thus considered in case of any EBV-associated LPDs.

Neurobehavioral evaluation of neonates with congenital heart disease: a cohort study.

AIM: To describe neurobehavioral patterns in neonates with congenital heart disease (CHD). METHOD: A cohort study describing neurobehavioral performance of neonates with CHD requiring cardiac surgery. The neonates were evaluated preoperatively and postoperatively with the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS) and scores were compared with published normative values. Clinical factors were obtained by chart review to assess their association with behavior. The CHD NNNS score pattern was compared with previously reported profiles in other high-risk populations. RESULTS: NNNS evaluations were completed on 67 neonates with CHD, resulting in 97 evaluations (50 preoperative, 47 postoperative). Compared with normative values, the cohort with CHD demonstrated decreased attention, regulation, asymmetry, stress, arousal, and excitability, along with increased non-optimal reflexes, lethargy, and need for handling (p<0.05 for all). Additional clinical factors had a minimal effect on the neurobehavioral pattern. Compared with previously published patterns in high-risk neonates without CHD, the cohort with CHD demonstrated a unique pattern of behavior. INTERPRETATION: Neonates with CHD demonstrate different neurobehavioral performance compared with typically developing neonates born at term as well as other high-risk neonates. Our experience suggests there is a unique neonatal neurobehavioral pattern in the hospitalized population with CHD. Targeted neonatal neurobehavioral evaluations may be useful in developing specific therapies to improve neurodevelopmental outcomes in neonates with CHD. WHAT THIS PAPER ADDS: Neonates with congenital heart disease demonstrate different neurobehavioral performance than typically developing neonates. Evaluation of neonatal neurobehavioral performance provides an opportunity to identify neurodevelopmental variability early. Identification of neurobehavioral performance variability allows targeted interactions and therapy.

Motor dysfunction in NF1: Mediated by attention deficit or inherent to the disorder?

AIM: Attention deficit and compromised motor skills are both prevalent in Neurofibromatosis type 1 (NF1), but the relationship is unclear. We investigated motor function in children with NF1 and in children with Attention Deficit/Hyperactivity Disorder (ADHD), and explored if, in patients with NF1, attention deficit influences motor performance. METHODS: Motor performance was measured using the Movement Assessment Battery for Children (M-ABC) in 71 children (26 with NF1 plus ADHD, 14 with NF1 without ADHD, and 31 with ADHD without NF1) aged 6-12 years. RESULTS: There was a significant effect of group on motor performance. Both NF1 groups scored below children with ADHD without NF1. Attention performance mediated motor performance in children with ADHD without NF1, but not in children with NF1. CONCLUSIONS: Motor function is not mediated by attention performance in children with NF1. While in ADHD, attention deficit influences motor performance, motor problems in NF1 seem to be independent from attention deficit. This argues for different pathomechanisms in these two groups of developmental disorders.

Loss of RASGRP1 in humans impairs T-cell expansion leading to Epstein-Barr virus susceptibility.

Inherited CTPS1, CD27, and CD70 deficiencies in humans have revealed key factors of T-lymphocyte expansion, a critical prerequisite for an efficient immunity to Epstein-Barr virus (EBV) infection. RASGRP1 is a T-lymphocyte-specific nucleotide exchange factor known to activate the pathway of MAP kinases (MAPK). A deleterious homozygous mutation in RASGRP1 leading to the loss RASGRP1 expression was identified in two siblings who both developed a persistent EBV infection leading to Hodgkin lymphoma. RASGRP1-deficient T cells exhibited defective MAPK activation and impaired proliferation that was restored by expression of wild-type RASGRP1. Similar defects were observed in T cells from healthy individuals when RASGRP1 was downregulated. RASGRP1-deficient T cells also exhibited decreased CD27-dependent proliferation toward CD70-expressing EBV-transformed B cells, a crucial pathway required for expansion of antigen-specific T cells during anti-EBV immunity. Furthermore, RASGRP1-deficient T cells failed to upregulate CTPS1, an important enzyme involved in DNA synthesis. These results show that RASGRP1 deficiency leads to susceptibility to EBV infection and demonstrate the key role of RASGRP1 at the crossroad of pathways required for the expansion of activated T lymphocytes.

RASGRP1 mutation in autoimmune lymphoproliferative syndrome-like disease.

BACKGROUND: Autoimmune lymphoproliferative syndrome (ALPS) is a genetic disorder of lymphocyte homeostasis due to impaired apoptosis. It was initially regarded as a very rare disease, but recent studies show that it may be more common than previously thought. Defects in a couple of genes have been identified in a proportion of patients with ALPS, but around one-third of such patients remain undefined genetically. OBJECTIVE: We describe 2 siblings presenting with ALPS-like disease. This study aimed to identify the genetic cause responsible for this phenotype. METHODS: Whole-exome sequencing and molecular and functional analyses were used to identify and characterize the genetic defect. Clinical and immunological analysis was also performed and reported. RESULTS: The 2 patients presented with chronic lymphadenopathy, hepatosplenomegaly, autoimmune hemolytic anemia, immune thrombocytopenia, and the presence of antinuclear autoantibody and other autoantibodies, but normal double-negative T cells. They also suffered from recurrent infections. Novel compound heterozygous mutations of RASGRP1 encoding Ras guanyl nucleotide releasing protein 1 were identified in the 2 siblings. The mutations impaired T-cell receptor signaling, leading to defective T-cell activation and proliferation, as well as impaired activation-induced cell death of T cells. CONCLUSIONS: This study shows for the first time that RASGRP1 mutation should be considered in patients with ALPS-like disease. We also propose to investigate the intracellular proteins involved in the T-cell receptor signaling pathway in similar patients but with unknown genetic cause.