Novel frameshift variants expand the map of the genetic defects in IRF2BP2

BackgroundAt present, the knowledge about disease-causing mutations in IRF2BP2 is very limited because only a few patients affected by this condition have been reported. As previous studies have described, the haploinsufficiency of this interferon transcriptional corepressors leads to the development of CVID. Very recently, a more accurate phenotype produced by truncating variants in this gene has been defined, manifesting CVID with gastrointestinal inflammatory symptoms and autoimmune manifestations.MethodsWe analyzed 5 index cases with suspected primary immunodeficiency by high throughput sequencing. They were submitted for a genetic test with a panel of genes associated with immune system diseases, including IRF2BP2. The screening of SNVs, indels and CNVs fulfilling the criteria with very low allelic frequency and high protein impact, revealed five novel variants in IRF2BP2. In addition, we isolated both wild-type and mutated allele of the cDNA from one of the families.ResultsIn this study, we report five novel loss-of-function (LoF) mutations in IRF2BP2 that likely cause primary immunodeficiency, with CVID as more frequent phenotype, variable expression of inflammatory gastrointestinal features, and one patient with predisposition of viral infection. All identified variants were frameshift changes, and one of them was a large deletion located on chromosome 1q42, which includes the whole sequence of IRF2BP2, among other genes. Both de novo and dominant modes of inheritance were observed in the families here presented, as well as incomplete penetrance.ConclusionsWe describe novel variants in a delimited low-complex region, which may be considered a hotspot in IRF2BP2. Moreover, this is the first time that a large CNV in IRF2BP2 has been reported to cause CVID. The distinct mechanisms than LoF in IRF2BP2 could cause different phenotype compared with the mainly described. Further investigations are necessary to comprehend the regulatory mechanisms of IRF2BP2, which could be under variable expression of the disease

Higher COVID-19 pneumonia risk associated with anti-IFN-α than with anti-IFN-ω auto-Abs in children

COVID-19; Immunodeficiency; Infectious diseaseCOVID-19; Inmunodeficiencia; Enfermedad infecciosaCOVID-19; Immunodeficiència; Malaltia infecciosaWe found that 19 (10.4%) of 183 unvaccinated children hospitalized for COVID-19 pneumonia had autoantibodies (auto-Abs) neutralizing type I IFNs (IFN-α2 in 10 patients: IFN-α2 only in three, IFN-α2 plus IFN-ω in five, and IFN-α2, IFN-ω plus IFN-β in two; IFN-ω only in nine patients). Seven children (3.8%) had Abs neutralizing at least 10 ng/ml of one IFN, whereas the other 12 (6.6%) had Abs neutralizing only 100 pg/ml. The auto-Abs neutralized both unglycosylated and glycosylated IFNs. We also detected auto-Abs neutralizing 100 pg/ml IFN-α2 in 4 of 2,267 uninfected children (0.2%) and auto-Abs neutralizing IFN-ω in 45 children (2%). The odds ratios (ORs) for life-threatening COVID-19 pneumonia were, therefore, higher for auto-Abs neutralizing IFN-α2 only (OR [95% CI] = 67.6 [5.7–9,196.6]) than for auto-Abs neutralizing IFN-ω only (OR [95% CI] = 2.6 [1.2–5.3]). ORs were also higher for auto-Abs neutralizing high concentrations (OR [95% CI] = 12.9 [4.6–35.9]) than for those neutralizing low concentrations (OR [95% CI] = 5.5 [3.1–9.6]) of IFN-ω and/or IFN-α2.The Laboratory of Human Genetics of Infectious Diseases is supported by the Howard Hughes Medical Institute, the Rockefeller University, the St. Giles Foundation, the National Institutes of Health (NIH) (R01AI088364, R01AI163029, and R21AI160576), the National Center for Advancing Translational Sciences, the NIH Clinical and Translational Science Award program (UL1TR001866), the Fisher Center for Alzheimer’s Research Foundation, the Meyer Foundation, the JPB Foundation, the Stavros Niarchos Foundation Institute for Global Infectious Disease Research, the program “Investissement d’Avenir” launched by the French Government and implemented by the Agence Nationale de la Recherche (ANR) (ANR-10-IAHU-01), the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (ANR-10-LABX-62-IBEID), the French Foundation for Medical Research (FRM) (EQU201903007798), the ANRS-COV05, ANR GENVIR (ANR-20-CE93-003), ANR AI2D (ANR-22-CE15-0046), and ANR AAILC (ANR-21-LIBA-0002) projects, the European Union’s Horizon 2020 research and innovation program under grant agreement no. 824110 (EASI-genomics), the HORIZON-HLTH-2021-DISEASE-04 program under grant agreement 01057100 (UNDINE), the ANR-RHU COVIFERON Program (ANR-21-RHUS-08), the Square Foundation, Grandir - Fonds de solidarité pour l’enfance, the Fondation du Souffle, the SCOR Corporate Foundation for Science, The French Ministry of Higher Education, Research, and Innovation (MESRI-COVID-19), Institut National de la Santé et de la Recherche Médicale (INSERM), REACTing-INSERM, the University of Paris Cité and Imagine Institute, Battersea & Bowery Advisory Group, and William E. Ford, General Atlantic’s Chairman and Chief Executive Officer, Gabriel Caillaux, General Atlantic’s Co-President, Managing Director and Head of Business in EMEA, and the General Atlantic Foundation. I. Meyts is a senior clinical researcher at FWO Vlaanderen; I. Meyts is funded by the European Research Council under HORIZON-HLTL-2021-ID: 101057100 "Undine," KU Leuven C16/18/007, and FWO grant G0B5120N (DADA2). L.D. Notarangelo and H.C. Su (members of the COVID Human Genetic Effort) were supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases, NIH. P. Bastard was supported by the French Foundation for Medical Research (FRM, EA20170638020). P. Bastard and T. Le Voyer were supported by the MD-PhD program of the Imagine Institute (with the support of the Fondation Bettencourt-Schueller). P. Bastard was supported by the “Poste CCA-INSERM-Bettencourt” (with the support of the Fondation Bettencourt-Schueller). S. Okada was supported by MEXT/JSPS KAKENHI (grant numbers 22H03041 and 22KK0113) and AMED (grant numbers JP21fk0108436 and JP22fk0108514). L.I. Gonzalez-Granado is supported by the Instituto de Salud Carlos III (ISCIII) through the project FIS-PI21/01642 and cofunded by the European Union. D.C. Vinh is supported by a Fonds de Recherche du Québec - Santé, Senior Clinician-Scientist scholar award. Q. Pan-Hammarström was funded by the Swedish Research Council, and the Knut and Alice Wallenberg Foundation. K. Kisand’s laboratory was funded by the Estonian Research Council grants PRG1117 and PRG1428. This study also received support from ISCIII (TRINEO: PI22/00162; DIAVIR: DTS19/00049; Resvi-Omics: PI19/01039 [A. Salas]; ReSVinext: PI16/01569 [F. Martinón-Torres]; Enterogen: PI19/01090 [F. Martinón-Torres]); OMI-COVI-VAC (PI22/00406 [F. Martinón-Torres] jointly financed by FEDER), GAIN: Grupos con Potencial de Crecimiento (IN607B 2020/08 [A. Salas]); ACIS: BI-BACVIR (PRIS-3 [A. Salas]), and CovidPhy (SA 304 C [A. Salas]); and consorcio Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CB21/06/00103; F. Martinón-Torres); GEN-COVID (IN845D 2020/23, F. Martinón-Torres) and Grupos de Referencia Competitiva (IIN607A2021/05, F. Martinón-Torres). The study was funded by ISCIII (COV20_01333, COV20_01334, PI16/00759, PI18/00223, PI19/00208, PI20/00876, and PI21/00211), the Spanish Ministry of Science and Innovation (RTC-2017-6471-1; AEI/FEDER, EU), the Fundación Canaria Instituto de Investigación Sanitaria de Canarias (FIISC19/43, PIFIISC22/27), Grupo DISA (OA18/017), Fundación MAPFRE Guanarteme (OA21/131), Cabildo Insular de Tenerife (CGIEU0000219140 and “Apuestas científicas del ITER para colaborar en la lucha contra la COVID-19”). A. Pujol is supported by ACCI20-759 CIBERER, H2020 Marató TV3 COVID 2021-31-33, the HORIZON-HLTH-2021-ID: 101057100 (UNDINE), the Horizon 2020 program under grant no. 824110 (EasiGenomics grant no. COVID-19/PID12342), and the CERCA Program/Generalitat de Catalunya. This research is supported by the European Reference Network for Rare Immunodeficiency, Autoinflammatory and Autoimmune Diseases. Open Access funding provided by Rockefeller University

Case Report: Characterizing the Role of the STXBP2-R190C Monoallelic Mutation Found in a Patient With Hemophagocytic Syndrome and Langerhans Cell Histiocytosis

Histiocitosi de cèl·lules de Langerhans; Desgranulació; Exocitosi de grànuls líticsHistiocitosis de células de Langerhans; Desgranulación; Exocitosis de gránulos líticosLangerhans-cell-histiocytosis; Degranulation; Lytic granule exocytosisHemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory disorder. HLH can be considered as a threshold disease depending on the trigger and the residual NK-cell cytotoxicity. In this study, we analyzed the molecular and functional impact of a novel monoallelic mutation found in a patient with two episodes of HLH. A 9-month-old child was diagnosed at 2 months of age with cutaneous Langerhans cell histiocytosis (LCH). After successful treatment, the patient developed an HLH episode. At 16 month of age, the patient went through an HSCT losing the engraftment 5 months later concomitant with an HLH relapse. The genetic study revealed a monoallelic mutation in the STXBP2 gene (.pArg190Cys). We transfected COS7 cells to analyze the STXBP2-R190C expression and to test the interaction with STX11. We used the RBL-2H3 cell line expressing STXBP2-WT-EGFP or R190C-EGFP for degranulation assays. Mutation STXBP2-R190C did not affect protein expression or interaction with syntaxin-11. However, we have demonstrated that STXBP2-R190C mutation diminishes degranulation in the RBL-2H3 cell line compared with the RBL-2H3 cell line transfected with STXBP2-WT or nontransfected. These results suggest that STXBP2-R190C mutation acts as a modifier of the degranulation process producing a decrease in degranulation. Therefore, under homeostatic conditions, the presence of one copy of STXBP2-R190 could generate sufficient degranulation capacity. However, it is likely that early in life when adaptive immune system functions are not sufficiently developed, an infection may not be resolved with this genetic background, leading to a hyperinflammation syndrome and eventually develop HLH. This analysis highlights the need for functional testing of new mutations to validate their role in genetic susceptibility and to establish the best possible treatment for these patients.This work was funded by the Instituto de Salud Carlos III, grants PI17/00660 and PI18/00346, co-financed by the European Regional Development Fund (ERDF)

CD26/DPPIV Inhibition alters the expression of immune response-related genes in the thymi of NOD mice

The transmembrane glycoprotein CD26 or dipeptidyl peptidase IV (DPPIV) is a multifunctional protein. In immune system, CD26 plays a role in T-cell function and is also involved in thymic maturation and emigration patterns. In preclinical studies, treatment with DPPIV inhibitors reduces insulitis and delays or even reverses the new onset of type 1 diabetes (T1D) in non-obese diabetic (NOD) mice. However, the specific mechanisms involved in these effects remain unknown. The aim of the present study was to investigate how DPPIV inhibition modifies the expression of genes in the thymus of NOD mice by microarray analysis. Changes in the gene expression of β-cell autoantigens and Aire in thymic epithelial cells (TECs) were also evaluated by using qRT-PCR. A DPPIV inhibitor, MK626, was orally administered in the diet for 4 and 6 weeks starting at 6-8 weeks of age. Thymic glands from treated and control mice were obtained for each study checkpoint. Thymus transcriptome analysis revealed that 58 genes were significantly over-expressed in MK626-treated mice after 6 weeks of treatment. Changes in gene expression in the thymus were confined mainly to the immune system, including innate immunity, chemotaxis, antigen presentation and immunoregulation. Most of the genes are implicated in central tolerance mechanisms through several pathways. No differences were observed in the expression of Aire and β-cell autoantigens in TECs. In the current study, we demonstrate that treatment with the DPPIV inhibitor MK626 in NOD mice alters the expression of the immune response-related genes in the thymus, especially those related to immunological central tolerance, and may contribute to the prevention of T1D

Regulation of TSHR expression in the thyroid and thymus may contribute to TSHR tolerance failure in graves’ disease patients via two distinct mechanisms

Graves’ disease; TSHR; ToleranceMalaltia de Graves; TSHR; TolerànciaEnfermedad de Graves; TSHR; ToleranciaGraves' disease (GD) involves the presence of agonistic auto-antibodies against the thyrotropin receptor (TSHR), which are responsible for the clinical symptoms. While failure of TSHR tolerance is central to GD pathogenesis, the process leading to this failure remains poorly understood. Two mechanisms intimately linked to tolerance have been proposed to explain the association of SNPs located in TSHR intron 1 to GD: (1) differential alternative splicing in the thyroid; and (2) modulation of expression in the thymus. To elucidate the relative contribution to these two mechanisms to GD pathogenesis, we analyzed the level of full-length and ST4 and ST5 isoform expression in the thyroid (n = 49) and thymus (n = 39) glands, and the influence of intron 1-associated SNPs on such expression. The results show that: (1) the level of flTSHR and ST4 expression in the thymus was unexpectedly high (20% that of the thyroid); (2) while flTSHR is the predominant isoform, the levels are similar to ST4 (ratio flTSHR/ST4 = 1.34 in the thyroid and ratio flTSHR/ST4 in the thymus = 1.93); (3) next-generation sequencing confirmed the effect of the TSHR intron 1 polymorphism on TSHR expression in the thymus with a bias of 1.5 ± 0.2 overexpression of the protective allele in the thymus compared to the thyroid; (4) GD-associated intron 1 SNPs did not influence TSHR alternative splicing of ST4 and ST5 in the thyroid and thymus; and (5) three-color confocal imaging showed that TSHR is associated with both thymocytes, macrophages, and dendritic cells in the thymus. Our findings confirm the effect of intron 1 polymorphisms on thymic TSHR expression and we present evidence against an effect on the relative expression of isoforms. The high level of ST4 expression in the thymus and its distribution within the tissue suggest that this would most likely be the isoform that induces central tolerance to TSHR thus omitting most of the hinge and transmembrane portion. The lack of central tolerance to a large portion of TSHR may explain the relatively high frequency of autoimmunity related to TSHR and its clinical consequence, GD.This study was funded by Instituto de Salud Carlos III, grants PI14/00848, and PI17/00324, co-financed by the European Regional Development Fund (ERDF). DÁ-S is in recipient of a predoctoral fellowship from the Vall d’Hebron Research Institute (VHIR)

Early Diagnosis and Treatment of Purine Nucleoside Phosphorylase (PNP) Deficiency through TREC-Based Newborn Screening

Newborn screening; Severe combined immunodeficiencyCribatge nounat; Immunodeficiència combinada severaCribado neonato; Inmunodeficiencia combinada gravePurine nucleoside phosphorylase (PNP) deficiency is a rare inherited disorder, resulting in severe combined immunodeficiency. To date, PNP deficiency has been detected in newborn screening only through the use of liquid chromatography tandem mass spectrometry. We report the first case in which PNP deficiency was detected by TREC analysis.This research was funded by Jeffrey Modell Foundation

Common Variable Immunodeficiency and Neurodevelopmental Delay Due to a 13Mb Deletion on Chromosome 4 Including the NFKB1 Gene: A Case Report

Chromosomal rearrangements; Primary immunodeficiencies; Syndromic immunodeficienciesReordenacions cromosòmiques; Immunodeficiències primàries; Immunodeficiències sindròmiquesReordenamientos cromosómicos; Inmunodeficiencias primarias; Inmunodeficiencias sindrómicasSyndromic immunodeficiencies are a heterogeneous group of inborn errors of immunity that can affect the development of non-immune organs and systems. The genetic basis of these immunodeficiencies is highly diverse, ranging from monogenic defects to large chromosomal aberrations. Antibody deficiency is the most prevalent immunological abnormality in patients with syndromic immunodeficiencies caused by chromosomal rearrangements, and usually manifests as a common variable immunodeficiency (CVID)-like phenotype. Here we describe a patient with a complex phenotype, including neurodevelopmental delay, dysmorphic features, malformations, and CVID (hypogammaglobulinemia, reduced pre-switch and switch memory B cells, and impaired vaccine response). Microarray-based comparative genomic hybridization (aCGH) revealed a 13-Mb deletion on chromosome 4q22.2-q24 involving 53 genes, some of which were related to the developmental manifestations in our patient. Although initially none of the affected genes could be linked to his CVID phenotype, subsequent reanalysis identified NFKB1 haploinsufficiency as the cause. This study underscores the value of periodic reanalysis of unsolved genetic studies performed with high-throughput technologies (eg, next-generation sequencing and aCGH). This is important because of the ongoing incorporation of new data establishing the relationship between genes and diseases. In the present case, NFKB1 had not been associated with human disease at the time aCGH was performed. Eight years later, reanalysis of the genes included in the chromosome 4 deletion enabled us to identify NFKB1 haploinsufficiency as the genetic cause of our patient’s CVID. In the future, other genes included in the deletion may be linked to human disease, allowing us to better define the molecular basis of our patient’s complex clinical phenotype.This study was funded by Instituto de Salud Carlos III, grants PI17/00660 and PI20/00761, cofinanced by the European Regional Development Fund (ERDF). This study was also funded by the Jeffrey Modell Foundation. This work is supported by the European Reference Network for Rare Immunodeficiency, Autoinflammatory and Autoimmune Diseases Network (ERN-RITA)

Newborn Screening for SCID: Experience in Spain (Catalonia)

Linfocitos T; Cribado de recién nacidos; Inmunodeficiencia combinada severaLimfòcits T; Cribratge de nounats; Immunodeficiència combinada severaT-lymphocytes; Newborn screening; Severe combined immunodeficiencyNewborn screening (NBS) for severe combined immunodeficiency (SCID) started in Catalonia in January-2017, being the first Spanish and European region to universally include this testing. In Spain, a pilot study with 5000 samples was carried out in Seville in 2014; also, a research project with about 35,000 newborns will be carried out in 2021–2022 in the NBS laboratory of Eastern Andalusia. At present, the inclusion of SCID is being evaluated in Spain. The results obtained in the first three and a half years of experience in Catalonia are presented here. All babies born between January-2017 and June-2020 were screened through TREC-quantification in DBS with the Enlite Neonatal TREC-kit from PerkinElmer. A total of 222,857 newborns were screened, of which 48 tested positive. During the study period, three patients were diagnosed with SCID: an incidence of 1 in 74,187 newborns; 17 patients had clinically significant T-cell lymphopenia (non-SCID) with an incidence of 1 in 13,109 newborns who also benefited from the NBS program. The results obtained provide further evidence of the benefits of early diagnosis and curative treatment to justify the inclusion of this disease in NBS programs. A national NBS program is needed, also to define the exact SCID incidence in Spain

Activation-induced deaminase is critical for the establishment of DNA methylation patterns prior to the germinal center reaction

Limfòcits b; Metilació de l'ADN; GenomaLinfocitos b; Metilación de ADN; GenomaB-lymphocytes; DNA methylation; GenomeActivation-induced deaminase (AID) initiates antibody diversification in germinal center B cells by deaminating cytosines, leading to somatic hypermutation and class-switch recombination. Loss-of-function mutations in AID lead to hyper-IgM syndrome type 2 (HIGM2), a rare human primary antibody deficiency. AID-mediated deamination has been proposed as leading to active demethylation of 5-methycytosines in the DNA, although evidence both supports and casts doubt on such a role. In this study, using whole-genome bisulfite sequencing of HIGM2 B cells, we investigated direct AID involvement in active DNA demethylation. HIGM2 naïve and memory B cells both display widespread DNA methylation alterations, of which ∼25% are attributable to active DNA demethylation. For genes that undergo active demethylation that is impaired in HIGM2 individuals, our analysis indicates that AID is not directly involved. We demonstrate that the widespread alterations in the DNA methylation and expression profiles of HIGM2 naïve B cells result from premature overstimulation of the B-cell receptor prior to the germinal center reaction. Our data support a role for AID in B cell central tolerance in preventing the expansion of autoreactive cell clones, affecting the correct establishment of DNA methylation patterns.Spanish Ministry of Science, Innovation and Universities [SAF2017-88086-R to E.B.]; cofunded by FEDER funds/European Regional Development Fund (ERDF)—a way to build Europe. E.B is supported by Instituto de Salud Carlos III (ISCIII), Ref. AC18/00057, associated with i-PAD project (ERARE European Union program); P.L. and C.P. are supported by the German Cancer Aid project CO-CLL [70113869]; B.G. is funded by the Deutsche Forschungsgemeinschaft [GR1617/14-1/iPAD, SFB1160/2_B5, RESIST–EXC 2155–Project ID 390874280, CIBSS–EXC-2189–Project ID 390939984]; BMBF [GAIN 01GM1910A]. Funding for open access charge: Spanish Ministry of Science, Innovation and Universities [SAF2017-88086-R]