Common Variable Immunodeficiency: More Pathways than Roads to Rome

Selective IgM Hypogammaglobulinemia and Multiple Sclerosis Treated with Natalizumab and Ofatumumab: A Case Report

Background: B-cell-depleting drugs targeting the CD20 antigen have been increasingly implemented as an "exit strategy" from natalizumab for relapsing-remitting multiple sclerosis (RRMS) patients due to the increased risk of progressive multifocal leukoencephalopathy. Data on recently approved anti-CD20 drugs, such as ofatumumab serving as a natalizumab "exit strategy", are lacking. Furthermore, due to their immunosuppressive mechanism of action, prolonged use of these "highly effective" drugs is associated with the development of hypogammaglobulinemia and, consequently, a higher risk of infections. There are no guidelines for monitoring serum immunoglobulin levels in individuals undergoing "highly effective" multiple sclerosis treatment. Methods: We present a case of a 26-year-old male RRMS patient with selective IgM deficiency and multiple sclerosis initially treated with natalizumab and later ofatumumab. Results: The patient achieved "no evident disease activity "status while undergoing treatment with natalizumab and ofatumumab, but these therapies, especially ofatumumab, greatly impacted further drops in IgM levels. However, no significant decrease in IgG levels was observed, and no infectious events occurred. In addition, the patient did not show signs of disease activity while on ofatumumab, which also offered a more convenient mode of administration. Conclusions: Our experience points to the need to further explore benefit-risk ratios of highly effective treatments, even in cases with low immunoglobulin levels. However, closely monitoring immunoglobulin levels and conducting clinical follow-ups to ensure prompt recognition of potential infectious complications constitute approaches that have been thought of for such patients.

Exploring Monogenic, Polygenic, and Epigenetic Models of Common Variable Immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent symptomatic inborn error of immunity (IEI). CVID is genetically heterogeneous and occurs in sporadic or familial forms with different inheritance patterns. Monogenic mutations have been found in a low percentage of patients, and multifactorial or polygenic inheritance may be involved in unsolved patients. In the complex disease model, the epistatic effect of multiple variants in several genes and environmental factors such as infections may contribute. Epigenetic modifications, such as DNA methylation changes, are also proposed to be involved in CVID pathogenesis. In general, the pathogenic mechanism and molecular basis of CVID disease are still unknown, and identifying patterns of association across the genome in polygenic models and epigenetic modification profiles in CVID requires more studies. Here, we describe the current knowledge of the molecular genetic basis of CVID from monogenic, polygenic, and epigenetic aspects.

The Histologic Spectrum of Rituximab-Associated Common Variable Immunodeficiency-Like Enteropathy

Rituximab (RTX) is a monoclonal anti-CD20 antibody widely used to treat B-cell neoplasms and autoimmune conditions. RTX has recently been linked to an enteropathy characterized by diarrhea, malabsorption, and hypogammaglobulinemia, closely resembling common variable immunodeficiency (CVID) enteropathy. We present the first dedicated histopathologic assessment of RTX-associated CVID-like enteropathy. Study inclusion criteria were the presence of diarrhea, weight loss, or other gastrointestinal (GI) symptoms in the setting of current/prior RTX use and associated hypogammaglobulinemia. Twenty-two patients (15M:7F; mean age at biopsy/resection, 63.4y) across 9 tertiary medical centers met inclusion criteria and had small bowel (N=20) and/or colon (N=17) specimens (biopsies/resections) available for review; 71.4% of specimens dated from ≤5y of last RTX dose. Cases were systematically evaluated by GI pathologists at each institution. Key histologic features in the small bowel included sparse/absent lamina propria plasma cells (N=10, 50%), intraepithelial lymphocytosis (N=12, 60%), villous atrophy (N=11, 55%), increased crypt apoptotic bodies (N=6, 30%), and active inflammation (N=5, 25%). Common features in the colon included sparse/absent plasma cells (N=7, 41.2%), increased crypt apoptotic bodies (N=7, 41.2%), active inflammation (N=5, 29.4%), and intraepithelial lymphocytosis (N=4, 23.5%). Goblet cell loss was appreciated in small bowel and/or colon specimens from 2 patients. Follow-up biopsies (interval, 2m-4y) were available for 7 patients and largely recapitulated the histology of the index specimens, though 1 patient demonstrated improvement in villous blunting and intraepithelial lymphocytosis. In summary, the histologic spectrum of post-RTX CVID-like enteropathy encompasses lamina propria plasma cell depletion, increased crypt apoptotic bodies, small bowel villous atrophy, and goblet cell loss. While the underlying pathophysiology remains uncertain, the clinicopathologic picture may reflect post-RTX B-cell/plasma cell impairment. Although histologic findings may be subtle and variable, pathologists should be aware of this entity and should seek a history of RTX use in patients whose biopsies exhibit these CVID enteropathy-like features.

The Burden of Non-Infectious Organ-Specific Immunopathology in Pediatric Common Variable Immunodeficiency

The pediatric common variable immunodeficiency (CVID) is the most frequent symptomatic antibody production defect characterized by infectious and non-infectious autoimmune, inflammatory, and lymphoproliferative complications. The background for CVID-related organ-specific immunopathology is associated with immune dysregulation and immunophenotypic biomarkers with expansion of CD21low B cells, and dysfunctional memory B cell, follicular T cell, and regulatory T cell compartments. The ever-increasing progress in immunogenetics shows the heterogeneity of genetic background for CVID related to the complexity of clinical phenotypes. Multiple systemic modulatory pathways are determined by variants in such genes as TACI or TNFRSF13B gene encoding for BAFF-R, CTLA-4, LRBA, NFKB1 and NFKB2, and PIK3CD or PIK3R1. The organ-specific immunopathology encompasses a spectrum of disorders associated with immune dysregulation, such as granulomatous interstitial lung disease, hepatocellular nodular regenerative hyperplasia, enteropathy, neuropathy, endocrinopathies, and dermatoses. This review is aimed to define and delineate the organ-specific immunopathology in pediatric CVID. It is also conducted to gather data facilitating a better understanding of complex and heterogeneous immunophenotypes in the context of immune dysregulation mechanisms and genetic background determining manifestations of the disease and implicating personalized targeted therapies with biological agents.

Inborn errors of immunity (primary immunodeficiencies)

Primary immunodeficiencies (PID), now often referred to as inborn errors of immunity (IEI), are a large heterogeneous group of disorders that result from deficiencies in immune system development and/or function. IEIs can be broadly classified as disorders of adaptive immunity (e.g., combined or humoral immunodeficiencies) or of innate immunity (e.g., phagocyte and complement disorders). Although the clinical manifestations of IEIs are highly variable, traditionally many disorders involve an increased susceptibility to infection. Research in recent years has underscored how IEI can present with features other than infection such as: severe atopy, autoimmunity, autoinflammation, lymphoproliferation, and/or malignancy resulting from immune dysregulation. Early consultation with a clinical immunologist is essential, as timely diagnosis and treatment are imperative for preventing significant disease-associated morbidity and mortality. The treatment of IEIs is complex and generally requires both supportive and definitive strategies, including but not limited to, immunoglobulin replacement therapy, antibiotic prophylaxis, immune response modifiers, and hematopoietic stem cell transplantation. This article provides an overview of the major categories of IEIs and strategies for the appropriate diagnosis and management of these disorders.

Loss-of-function variant in MAGT1 leading to XMEN disease in a Colombian patient with a common variable immunodeficiency

INTRODUCTION

Common variable immunodeficiency is a diagnosis of exclusion in immunodeficient patients with increased susceptibility to infections, hypogammaglobulinemia, deficient response to vaccination, or low percentages of switched memory B cells. In low- and middle-income countries, the elucidation and study of molecular defects in these patients may take decades.

OBJECTIVE

To elucidate the genetic defect conferring impaired immunity in a patient diagnosed with common variable immunodeficiency.

MATERIALS AND METHODS

The clinical phenotype was extracted from the clinical records. NKG2D expression in natural killer cells was evaluated by flow cytometry. The whole exome sequencing was performed in the patient and his parents. Sanger sequencing confirmed the pathogenic variant.

RESULTS

The patient suffered from upper respiratory and urinary tract infections, autoimmune hemolytic anemia, and hepatopathy. NKG2D was decreased in the different blood subpopulations of natural killer cells. Serologic and viral load studies for Epstein-Barr virus were positive, but no B-cell malignancies have been documented. The patient presented a nonsense variant in the exon 3 of the MAGT1 gen (c.409C>T, rs387906724) in the X chromosome, resulting in an amino acid substitution of arginine for a stop codon in the position 137 of the protein (R137X). The mother also carried the pathogenic variant in a heterozygous state.

CONCLUSIONS

We report the clinical case of the first Colombian male patient with a pathogenic variant in MAGT1 associated with XMEN disease. Genetic counseling and followup are recommended for families with similar cases to allow prompt detection of new cases.

High occurrence of autoimmune and lymphoproliferative manifestations in adults with common variable immunodeficiency in southern Taiwan

There are no reported case series of common variable immunodeficiency (CVID) from southern Taiwan. A 20-year review was performed in adult CVID from a southern Taiwan medical center. Patients with ages of 18 years or older were enrolled from May, 2003 to April, 2023. Twelve patients were identified, 8 females/4 males aged 23 to 68 (38.9 ± 13.4) with one to 11 years (5.0 ± 3.3) delay of diagnosis after disease onset. There were concomitant autoimmune disorders in 7 (58 %), splenomegaly in 10 (83 %), lymphadenopathy in 4 (25 %) and B-cell lymphoma in 2 (17 %). All received intravenous immunoglobulin (IVIg) infusion with improved autoimmune-mediated arthritis in 2. Patients with higher IgG trough levels (above 500 mg/dL) had a better survival than those with lower IgG trough levels. Adult CVID in southern Taiwan has a high occurrence of autoimmune and lymphoproliferative manifestations. Early diagnosis with IVIg infusion might improve the presentations.

A Novel Heterozygous NFKB2 Variant in a Multiplex Family with Common Variable Immune Deficiency and Autoantibodies Against Type I IFNs

We studied a family with three male individuals across two generations affected by common variable immune deficiency (CVID). We identified a novel missense heterozygous variant (c.2602T>A:p.Y868N) of NFKB2 in all patients and not in healthy relatives. Functional studies of the mutant allele in an overexpression system and of the patients' cells confirmed the deleteriousness of the NFKB2 variant and genotype, respectively, on the activation of the non-canonical NF-κB signaling pathway. Impaired processing of p100 into p52 underlies p100 accumulation, which results in gain-of-function (GOF) of IκBδ inhibitory activity and loss-of-function (LOF) of p52 transcriptional activity. The three patients' plasma contained autoantibodies that neutralized IFN-α2 and/or IFN-ω, accounting for the severe or recurrent viral diseases of the patients, including influenza pneumonia in one sibling, and severe COVID-19 and recurrent herpes labialis in another. Our results confirm that NFKB2 alleles that are IκBδ GOF and p52 LOF can underlie CVID and drive the production of autoantibodies neutralizing type I IFNs, thereby predisposing to severe viral diseases.

Revealing disease subtypes and heterogeneity in common variable immunodeficiency through transcriptomic analysis

Common Variable Immunodeficiency (CVID) is a primary immunodeficiency characterized by reduced levels of specific immunoglobulins, resulting in frequent infections, autoimmune disorders, increased cancer risk, and diminished antibody production despite an adequate B cell count. With its clinical manifestations being highly variable, the classification of CVID, including the widely recognized Freiburg classification, is primarily based on clinical symptoms and genetic variations. Our study aims to refine the classification of CVID by analyzing transcriptomics data to identify distinct disease subtypes. We utilized the GSE51405 dataset, examining transcriptomic profiles from 30 CVID patients without complications. Employing a combination of clustering techniques-KMeans, hierarchical agglomerative clustering, spectral clustering, and Gaussian Mixture models-and differential gene expression analysis with R's limma package, we integrated molecular findings with demographic data (age and gender) through correlation analysis and identified common genes among clusters. Three distinct clusters of CVID patients were identified using KMeans, Agglomerative Clustering, and Gaussian Mixture Models, highlighting the disease's heterogeneity. Differential expression analysis unveiled 31 genes with variable expression levels across these clusters. Notably, nine genes (EIF5A, RPL21, ANP32A, DTX3L, NCF2, CDC42EP3, CHP1, FOLR3, and DEFA4) exhibited consistent differential expression across all clusters, independent of demographic factors. The study recommends categorizing patients based on the four genes, NCF2, CHP1, FOLR3, and DEFA4-as they may assist in prognostic prediction. Transcriptomic analysis of common variable immunodeficiency (CVID) patients identified three distinct clusters based on gene expression, independent of age and gender. Nine differentially expressed genes were identified across these clusters, suggesting potential biomarkers for CVID subtype classification. These findings highlight the genetic heterogeneity of CVID and provide novel insights into disease classification and potential personalized treatment approaches.

Immunogenetic Landscape in Pediatric Common Variable Immunodeficiency

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

Oral Diseases as a Manifestation of Inborn Errors of Immunity

Oral findings such as inflammation, ulcerations, or lesions can indicate serious systemic diseases and should prompt suspicion of acquired chronic conditions or inborn errors of immunity (IEIs). Currently, there are approximately 500 disease entities classified as IEIs, with the list expanding annually. The awareness of the existence of such conditions is of paramount importance, as patients with these disorders frequently necessitate the utilization of enhanced diagnostic techniques. This is exemplified by patients with impaired antibody production, in whom conventional serological methods may prove to be undiagnostic. Patients with IEI may require distinct therapeutic approaches or antimicrobial prophylaxis throughout their lives. An accurate diagnosis and, more importantly, early identification of patients with immune deficiencies is crucial to ensure the quality and longevity of their lives. It is important to note that the failure to establish a proper diagnosis or to provide adequate treatment could also have legal implications for medical professionals. The article presents IEIs, which may manifest in the oral cavity, and their diagnosis alongside therapeutic procedures.

Possible Role of Cytomegalovirus in Gastric Cancer Development and Recurrent Macrolide-Resistant Campylobacter jejuni Infection in Common Variable Immunodeficiency: A Case Report and Literature Discussion

Common variable immunodeficiency (CVID) is the most common symptomatic immunodeficiency in adults. It comprises a group of syndromes whose etiology involves genetic, epigenetic, microbiota, and environmental factors. We present the case of a 46-year-old Caucasian male patient with CVID and an immune dysregulation phenotype. The particular elements of the case consisted of an atypical clinical course, which undoubtedly demonstrates the great variability of clinical manifestations that these types of patients can suffer from, including bacterial and viral infections, autoimmune phenomena, and neoplasia. Notably, the patient suffered from recurrent gastrointestinal infection with macrolide-resistant Campylobacter jejuni and gastroduodenal disease and viraemia by cytomegalovirus (CMV). In addition, CMV was postulated as the main pro-oncogenic factor contributing to the development of early-onset intestinal-type gastric adenocarcinoma, for which the patient underwent gastrectomy. The patient's evolution was difficult, but finally, as a result of the multidisciplinary approach, clinical stabilization and improvement in his quality of life were achieved. Based on our brief literature review, this is the first reported case of this clinical complexity. Our experience could help with the management of future patients with CVID and may also update current epidemiological data on CVID.

Altered Genome-Wide DNA Methylation in the Duodenum of Common Variable Immunodeficiency Patients

PURPOSE

A large proportion of Common variable immunodeficiency (CVID) patients has duodenal inflammation with increased intraepithelial lymphocytes (IEL) of unknown aetiology. The histologic similarities to celiac disease, lead to confusion regarding treatment (gluten-free diet) of these patients. We aimed to elucidate the role of epigenetic DNA methylation in the aetiology of duodenal inflammation in CVID and differentiate it from true celiac disease.

METHODS

DNA was isolated from snap-frozen pieces of duodenal biopsies and analysed for differences in genome-wide epigenetic DNA methylation between CVID patients with increased IEL (CVID_IEL; n = 5) without IEL (CVID_N; n = 3), celiac disease (n = 3) and healthy controls (n = 3).

RESULTS

The DNA methylation data of 5-methylcytosine in CpG sites separated CVID and celiac diseases from healthy controls. Differential methylation in promoters of genes were identified as potential novel mediators in CVID and celiac disease. There was limited overlap of methylation associated genes between CVID_IEL and Celiac disease. High frequency of differentially methylated CpG sites was detected in over 100 genes nearby transcription start site (TSS) in both CVID_IEL and celiac disease, compared to healthy controls. Differential methylation of genes involved in regulation of TNF/cytokine production were enriched in CVID_IEL, compared to healthy controls.

CONCLUSION

This is the first study to reveal a role of epigenetic DNA methylation in the etiology of duodenal inflammation of CVID patients, distinguishing CVID_IEL from celiac disease. We identified potential biomarkers and therapeutic targets within gene promotors and in high-frequency differentially methylated CpG regions proximal to TSS in both CVID_IEL and celiac disease.

The Etiologic Landscape of Lymphoproliferation in Childhood: Proposal for a Diagnostic Approach Exploring from Infections to Inborn Errors of Immunity and Metabolic Diseases

Lymphoproliferation is defined by lymphadenopathy, splenomegaly, hepatomegaly, or lymphocytic organ and tissue infiltration. The most common etiologies of lymphoproliferation are represented by infectious diseases and lymphoid malignancies. However, it is increasingly recognized that lymphoproliferative features can be the presenting sign of rare conditions, including inborn errors of immunity (IEI) and inborn errors of metabolism (IEM). Among IEI, lymphoproliferation is frequently observed in autoimmune lymphoproliferative syndrome (ALPS) and related disorders, common variable immunodeficiency (CVID), activated phosphoinositide 3-kinase δ syndrome, and Epstein-Barr virus (EBV)-related disorders. Gaucher disease and Niemann-Pick disease are the most common IEMs that can present with isolated lymphoproliferative features. Notably, other rare conditions, such as sarcoidosis, Castleman disease, systemic autoimmune diseases, and autoinflammatory disorders, should be considered in the differential diagnosis of patients with persistent lymphoproliferation when infectious and malignant diseases have been reasonably ruled out. The clinical features of lymphoproliferative diseases, as well as the associated clinical findings and data deriving from imaging and first-level laboratory investigations, could significantly help in providing the correct diagnostic suspicion for the underlying etiology. This paper reviews the most relevant diseases associated with lymphoproliferation, including infectious diseases, hematological malignancies, IEI, and IEM. Moreover, some practical indications to orient the initial diagnostic process are provided, and two diagnostic algorithms are proposed for the first-level assessment and the approach to persistent lymphoproliferation, respectively.

Clinical and experimental treatment of primary humoral immunodeficiencies

Selective IgA deficiency (sIgAD), common variable immunodeficiency (CVID), and transient hypogammaglobulinemia of infancy (THI) are the most frequent forms of primary antibody deficiencies. Difficulties in initial diagnosis, especially in the early childhood, the familiar occurrence of these diseases, as well as the possibility of progression to each other suggest common cellular and molecular patomechanism and a similar genetic background. In this review, we discuss both similarities and differences of these three humoral immunodeficiencies, focusing on current and novel therapeutic approaches. We summarize immunoglobulin substitution, antibiotic prophylaxis, treatment of autoimmune diseases, and other common complications, i.e. cytopenias, gastrointestinal complications, and granulomatous disease. We discuss novel therapeutic approaches such as allogenic stem cell transplantation and therapies targeting-specific proteins, dependent on the patient's genetic defect. The diversity of possible therapeutics models results from a great heterogeneity of the disease variants, implying the need of personalized medicine approach as a future of primary humoral immunodeficiencies treatment.

Cross-population applications of genomics to understand the risk of multifactorial traits involving inflammation and immunity

The interplay between genetic and environmental factors plays a significant role in interindividual variation in immune and inflammatory responses. The availability of high-throughput low-cost genotyping and next-generation sequencing has revolutionized our ability to identify human genetic variation and understand how this varies within and between populations, and the relationship with disease. In this review, we explore the potential of genomics for patient benefit, specifically in the diagnosis, prognosis and treatment of inflammatory and immune-related diseases. We summarize the knowledge arising from genetic and functional genomic approaches, and the opportunity for personalized medicine. The review covers applications in infectious diseases, rare immunodeficiencies and autoimmune diseases, illustrating advances in diagnosis and understanding risk including use of polygenic risk scores. We further explore the application for patient stratification and drug target prioritization. The review highlights a key challenge to the field arising from the lack of sufficient representation of genetically diverse populations in genomic studies. This currently limits the clinical utility of genetic-based diagnostic and risk-based applications in non-Caucasian populations. We highlight current genome projects, initiatives and biobanks from diverse populations and how this is being used to improve healthcare globally by improving our understanding of genetic susceptibility to diseases and regional pathogens such as malaria and tuberculosis. Future directions and opportunities for personalized medicine and wider application of genomics in health care are described, for the benefit of individual patients and populations worldwide.

Role of Skewed X-Chromosome Inactivation in Common Variable Immunodeficiency

The term common variable immunodeficiency (CVID) encompasses a clinically diverse group of disorders, mainly characterized by hypogammaglobulinemia, insufficient specific antibody production, and recurrent infections. The genetics of CVID is complex, and monogenic defects account for only a portion of cases, typically <30%. Other proposed mechanisms include digenic, oligogenic, or polygenic inheritance and epigenetic dysregulation. In this study, we aimed to assess the role of skewed X-chromosome inactivation (XCI) in CVID. Within our cohort of 131 genetically analyzed CVID patients, we selected female patients with rare variants in CVID-associated genes located on the X-chromosome. Four patients harboring heterozygous variants in BTK (n = 2), CD40LG (n = 1), and IKBKG (n = 1) were included in the study. We assessed XCI status using the HUMARA assay and an NGS-based method to quantify the expression of the 2 alleles in mRNA. Three of the 4 patients (75%) exhibited skewed XCI, and the mutated allele was predominantly expressed in all cases. Patient 1 harbored a hypomorphic variant in BTK (p.Tyr418His), patient 3 had a pathogenic variant in CD40LG (c.288+1G>A), and patient 4 had a hypomorphic variant in IKBKG (p.Glu57Lys) and a heterozygous splice variant in TNFRSF13B (TACI) (c.61+2T>A). Overall, the analysis of our cohort suggests that CVID in a small proportion of females (1.6% in our cohort) is caused by skewed XCI and highly penetrant gene variants on the X-chromosome. Additionally, skewed XCI may contribute to polygenic effects (3.3% in our cohort). These results indicate that skewed XCI may represent another piece in the complex puzzle of CVID genetics.

Challenges for gene editing in common variable immunodeficiency disorders: Current and future prospects

The original CRISPR Cas9 gene editing system and subsequent innovations offers unprecedented opportunities to correct severe genetic defects including those causing Primary Immunodeficiencies (PIDs). Common Variable Immunodeficiency Disorders (CVID) are the most frequent symptomatic PID in adults and children. Unlike many other PIDs, patients meeting CVID criteria do not have a definable genetic defect and cannot be considered to have an inborn error of immunity (IEI). Patients with a CVID phenotype carrying a causative mutation are deemed to have a CVID-like disorder consequent to an IEI. Patients from consanguineous families often have highly penetrant early-onset autosomal recessive forms of CVID-like disorders. Individuals from non-consanguineous families may have autosomal dominant CVID-like disorders with variable penetrance and expressivity. This essay explores the potential clinical utility as well as the current limitations and risks of gene editing including collateral genotoxicity. In the immediate future the main application of this technology is likely to be the in vitro investigation of epigenetic and polygenic mechanisms, which are likely to underlie many cases of CVID and CVID-like disorders. In the longer-term, the CRISPR Cas9 system and other gene-based therapies could be utilized to treat CVID-like disorders, where the underlying IEI is known.

Telomere biology disorders may manifest as common variable immunodeficiency (CVID)

Telomere biology disorders (TBD) are caused by germline pathogenic variants in genes related to telomere maintenance and are characterized by critically short telomeres. In contrast to classical dyskeratosis congenita (DC), which is typically diagnosed in infancy, adult or late onset TBD frequently lack the typical DC triad and rather show variable organ manifestations and a cryptic disease course, thus complicating its diagnosis. Common variable immunodeficiency (CVID), on the other hand, is a primary antibody deficiency (PAD) syndrome. PADs are a heterogenous group of diseases characterized by hypogammaglobulinemia which occurs due to dysfunctional B lymphocytes and additional autoimmune and autoinflammatory complications. Genetic screening reveals a monogenic cause in a subset of CVID patients (15-35%). In our study, we screened the exomes of 491 CVID patients for the occurrence of TBD-related variants in 13 genes encoding for telomere/telomerase-associated proteins, which had previously been linked to the disease. We found 110/491 patients (22%) carrying 91 rare candidate variants in these 13 genes. Following the American College of Medical Genetics and Genomics (ACMG) guidelines, we classified two variants as benign, two as likely benign, 64 as variants of uncertain significance (VUS), four as likely pathogenic, and one heterozygous variant in an autosomal recessive disease gene as pathogenic. We performed telomere length measurement in 42 of the 110 patients with candidate variants and CVID. Two of these 42 patients showed significantly shorter telomeres compared to controls in both lymphocytes and granulocytes. Following the evaluation of the published literature and the patient's manifestations, we re-classified two VUS as likely pathogenic variants. Thus, 0.5-1% of all CVID patients in our study carry possibly pathogenic variants in telomere/telomerase-associated genes. Our data adds CVID to the broad clinical spectrum of cryptic adult-onset TBD. As the molecular diagnosis greatly impacts patient management and treatment strategies, we advise inclusion of all TBD-associated genes-despite their low prevalence-into the molecular screening of patients with antibody deficiencies.

Genetic characteristics of common variable immunodeficiency patients with autoimmunity

Background: The pathogenesis of common variable immunodeficiency disorder (CVID) is complex, especially when combined with autoimmunity. Genetic factors may be potential explanations for this complex situation, and whole genome sequencing (WGS) provide the basis for this potential. Methods: Genetic information of patients with CVID with autoimmunity, together with their first-degree relatives, was collected through WGS. The association between genetic factors and clinical phenotypes was studied using genetic analysis strategies such as sporadic and pedigree. Results: We collected 42 blood samples for WGS (16 CVID patients and 26 first-degree relatives of healthy controls). Through pedigree, sporadic screening strategies and low-frequency deleterious screening of rare diseases, we obtained 9,148 mutation sites, including 8,171 single-nucleotide variants (SNVs) and 977 Insertion-deletions (InDels). Finally, we obtained a total of 28 candidate genes (32 loci), of which the most common mutant was LRBA. The most common autoimmunity in the 16 patients was systematic lupus erythematosis. Through KEGG pathway enrichment, we identified the top ten signaling pathways, including "primary immunodeficiency", "JAK-STAT signaling pathway", and "T-cell receptor signaling pathway". We used PyMOL to predict and analyse the three-dimensional protein structures of the NFKB1, RAG1, TIRAP, NCF2, and MYB genes. In addition, we constructed a PPI network by combining candidate mutants with genes associated with CVID in the OMIM database via the STRING database. Conclusion: The genetic background of CVID includes not only monogenic origins but also oligogenic effects. Our study showed that immunodeficiency and autoimmunity may overlap in genetic backgrounds. Clinical Trial Registration: identifier ChiCTR2100044035.

Common variable immunodeficiency-an independent risk factor for atherosclerotic cardiovascular diseases

Atherosclerosis, a disease of chronic inflammation of the arterial wall, is the main cause of most cardiovascular diseases (CVDs). Common variable immunodeficiency (CVID), a group of diseases characterized by frequent infections due to defective antibody production and lack of human immunoglobulins, plays a role in immune activation and inflammation. Thus, it can be hypothesized that CVID increases the risk for atherosclerotic CVDs. On the other hand, it is also possible that CVID patients are protected from atherosclerotic CVDs based on their life-long immunoglobulin therapy. Here, we examined whether patients with CVID have an increased risk for atherosclerotic CVDs or whether they are protected from these diseases. Using an electronic patient database registry search of a population of 83 CVID patients and their age- and sex-matched, tenfold larger control population we demonstrate that CVID patients have a statistically significantly higher risk for coronary heart disease (OR 2.4, p = 0.015) and peripheral vascular disease (OR 12.5, p < 0.001). Regarding cerebrovascular disease, there was a trend towards CVID patients having more strokes or ischemic attacks, but the difference was not statistically significant (OR 2.0, p = 0.133). The combined OR for CVID patients for atherosclerotic CVDs was 2.6 (p = 0.001). CVID population had more hypertension, but smoking was more seldom. There were no statistically significant differences in the incidence of diabetes or levels of serum total, HDL or LDL cholesterol, or glycosylated hemoglobin A1c between CVID patients and their controls. CVID patients had infections more frequently and the OR for autoimmune diseases was 3.8 (p < 0.001). Finally, a multivariate logistic analysis showed that CVID is an independent risk factor for atherosclerotic CVDs (p = 0.002). The present study demonstrates for the first time that CVID is an independent risk factor for atherosclerotic CVDs. Further studies are required to fully understand the exact mechanisms behind this.

Interplay between epigenetic and genetic alterations in inborn errors of immunity

Inborn errors of immunity (IEIs) comprise a variety of immune conditions leading to infections, autoimmunity, allergy, and cancer. Some IEIs have no identified mutation(s), while others with identical mutations can display heterogeneous presentations. These observations suggest the involvement of epigenetic mechanisms. Epigenetic alterations can arise from downstream activation of cellular pathways through both extracellular stimulation and genetic-associated changes, impacting epigenetic enzymes or their interactors. Therefore, we posit that epigenetic alterations and genetic defects do not exclude each other as a disease-causing etiology. In this opinion, encompassing both basic and clinical viewpoints, we focus on selected IEIs with mutations in transcription factors that interact with epigenetic enzymes. The intricate interplay between these factors offers insights into genetic and epigenetic mechanisms in IEIs.

Next generation sequencing (NGS)-based approach to diagnosing Algerian patients with suspected inborn errors of immunity (IEIs)

The advent of next-generation sequencing (NGS) technologies has greatly expanded our understanding of both the clinical spectra and genetic landscape of inborn errors of immunity (IEIs). Endogamous populations may be enriched for unique, ancestry-specific disease-causing variants, a consideration that significantly impacts molecular testing and analysis strategies. Herein, we report on the application of a 2-step NGS-based testing approach beginning with targeted gene panels (TGPs) tailored to specific IEI subtypes and reflexing to whole exome sequencing (WES) if negative for Northwest Algerian patients with suspected IEIs. Our overall diagnostic yield of 57% is comparable to others broadly applying short-read NGS to IEI detection, but data from our localized cohort show some similarities and differences from NGS studies performed on larger regional IEI cohorts. This suggests the importance of tailoring diagnostic strategies to local demographics and needs, but also highlights ongoing concerns inherent to the application of genomics for clinical IEI diagnostics.

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

Background

At 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.

Methods

We 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.

Results

In 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.

Conclusions

We 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.

Cytokine dysregulation despite immunoglobulin replacement therapy in common variable immunodeficiency (CVID)

Introduction

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency. CVID is a heterogeneous disorder with a presumed multifactorial etiology. Intravenous or subcutaneous immunoglobulin replacement therapy (IgRT) can prevent severe infections but not underlying immune dysregulation.

Methods

In this study, we evaluated the serum concentrations of proinflammatory (TNF-α, IL-1β, IL-6) and immunoregulatory cytokines (IL-10), as well as lipopolysaccharide (LPS) and soluble CD14 (sCD14) in CVID individuals with infectious only (INF-CVID), and those with additional systemic autoimmune and inflammatory disorders (NIC-CVID), and healthy donors (HD).

Results

Our results showed increased serum concentrations of TNF-α, IL-1β, IL-6, and IL-10 in both INF-CVID and NIC-CVID subjects compared to HD. However, elevations of TNF-α, IL-1β, IL-6, and IL-10 were significantly more marked in NIC-CVID than INF-CVID. Additionally, LPS concentrations were increased only in NIC-CVID but not in INF-CVID compared to HD. Circulating levels of sCD14 were significantly increased in NIC-CVID compared to both INF-CVID and HD.

Discussion

These findings indicate persistent cytokine dysregulation despite IgRT in individuals with CVID. Moreover, the circulating cytokine profile reveals the heterogeneity of immune dysregulation in different subgroups of CVID subjects.

Case Report: Mycosis fungoides as an exclusive manifestation of common variable immunodeficiency in a family with a NFKB2 gene mutation

Background

Common variable immunodeficiency disorders (CVIDs), which are primary immunodeficiencies characterized by the failure of primary antibody production, typically present with recurrent bacterial infections, decreased antibody levels, autoimmune features, and rare atypical manifestations that can complicate diagnosis and management. Although most cases are sporadic, approximately 10% of the patients may have a family history of immunodeficiency. Genetic causes involving genes related to B-cell development and survival have been identified in only a small percentage of cases.

Case presentation

We present the case of a family with two brothers who presented with mycosis fungoides as an exclusive symptom of a common variable immunodeficiency disorder (CVID). Whole-exome sequencing of the index patient revealed a pathogenic variant of the NFKB2 gene. Based on this diagnosis and re-evaluation of other family members, the father and brother were diagnosed with this rare immune and preneoplastic syndrome. All CVID-affected family members presented with mycosis fungoides as their only symptom, which is, to the best of our knowledge, the first case to be reported.

Conclusion

This case highlights the importance of high-throughput sequencing techniques for the proper diagnosis and treatment of hereditary hematological disorders.

Disturbed lipid profile in common variable immunodeficiency - a pathogenic loop of inflammation and metabolic disturbances

The relationship between metabolic and inflammatory pathways play a pathogenic role in various cardiometabolic disorders and is potentially also involved in the pathogenesis of other disorders such as cancer, autoimmunity and infectious diseases. Common variable immunodeficiency (CVID) is the most common primary immunodeficiency in adults, characterized by increased frequency of airway infections with capsulated bacteria. In addition, a large proportion of CVID patients have autoimmune and inflammatory complications associated with systemic inflammation. We summarize the evidence that support a role of a bidirectional pathogenic interaction between inflammation and metabolic disturbances in CVID. This include low levels and function of high-density lipoprotein (HDL), high levels of triglycerides (TG) and its major lipoprotein very low-density lipoprotein (VLDL), and an unfavorable fatty acid (FA) profile. The dysregulation of TG, VLDL and FA were linked to disturbed gut microbiota profile, and TG and VLDL levels were strongly associated with lipopolysaccharides (LPS), a marker of gut leakage in blood. Of note, the disturbed lipid profile in CVID did not include total cholesterol levels or high low-density lipoprotein levels. Furthermore, increased VLDL and TG levels in blood were not associated with diet, high body mass index and liver steatosis, suggesting a different phenotype than in patients with traditional cardiovascular risk such as metabolic syndrome. We hypothesize that these metabolic disturbances are linked to inflammation in a bidirectional manner with disturbed gut microbiota as a potential contributing factor.