High frequencies of asymptomatic Epstein-Barr virus viremia in affected and unaffected individuals with CTLA4 mutations

2q33 Deletions Underlying Syndromic and Non-syndromic CTLA4 Deficiency

PURPOSE

CTLA4 deficiency is an inborn error of immunity (IEI) due to heterozygosity for germline loss-of-function variants of the CTLA4 gene located on chromosome 2q33.2. CTLA4 deficiency underlies pleiotropic immune and lymphoproliferation-mediated features with incomplete penetrance. It has been identified in hundreds of patients but copy number variants (CNVs) have been reported in only 12 kindreds, including nine which displayed large 2q33.1-2q33.2 deletions encompassing CTLA4.

METHODS

We conducted a nationwide study in France to identify patients with 2q33 deletions encompassing CTLA4. We investigated the clinical and immunological phenotypes and genotypes of these patients.

RESULTS

We identified 12 patients across six unrelated kindreds with clinical immunodeficiency. Neurological features were recorded in three patients, including one with syndromic neurodevelopmental disorder. Single-nucleotide polymorphism (SNP) or comparative genomic hybridization (CGH) array analysis, and targeted high-throughput sequencing revealed five different heterozygous 2q33 deletions of 26 kilobases to 7.12 megabases in size and encompassing one to 41 genes. We identified a contiguous gene syndrome (CGS) due to associated KLF7 deficiency in a kindred with a neurodevelopmental phenotype.

CONCLUSION

Deletions within the 2q33 region encompassing CTLA4 are rare and not extensively explored, and are probably underdiagnosed in cytogenetic practice. A literature review identified 14 different CGS loci including at least one gene responsible for an IEI. The deletions involved in IEIs should be systematically delimited, to facilitate screening for CGS.

Genetic Evaluation of the Patients with Clinically Diagnosed Inborn Errors of Immunity by Whole Exome Sequencing: Results from a Specialized Research Center for Immunodeficiency in Türkiye

Molecular diagnosis of inborn errors of immunity (IEI) plays a critical role in determining patients' long-term prognosis, treatment options, and genetic counseling. Over the past decade, the broader utilization of next-generation sequencing (NGS) techniques in both research and clinical settings has facilitated the evaluation of a significant proportion of patients for gene variants associated with IEI. In addition to its role in diagnosing known gene defects, the application of high-throughput techniques such as targeted, exome, and genome sequencing has led to the identification of novel disease-causing genes. However, the results obtained from these different methods can vary depending on disease phenotypes or patient characteristics. In this study, we conducted whole-exome sequencing (WES) in a sizable cohort of IEI patients, consisting of 303 individuals from 21 different clinical immunology centers in Türkiye. Our analysis resulted in likely genetic diagnoses for 41.1% of the patients (122 out of 297), revealing 52 novel variants and uncovering potential new IEI genes in six patients. The significance of understanding outcomes across various IEI cohorts cannot be overstated, and we believe that our findings will make a valuable contribution to the existing literature and foster collaborative research between clinicians and basic science researchers.

Too much of a good thing: a review of primary immune regulatory disorders

Primary immune regulatory disorders (PIRDs) are inborn errors of immunity caused by a loss in the regulatory mechanism of the inflammatory or immune response, leading to impaired immunological tolerance or an exuberant inflammatory response to various stimuli due to loss or gain of function mutations. Whilst PIRDs may feature susceptibility to recurrent, severe, or opportunistic infection in their phenotype, this group of syndromes has broadened the spectrum of disease caused by defects in immunity-related genes to include autoimmunity, autoinflammation, lymphoproliferation, malignancy, and allergy; increasing focus on PIRDs has thus redefined the classical 'primary immunodeficiency' as one aspect of an overarching group of inborn errors of immunity. The growing number of genetic defects associated with PIRDs has expanded our understanding of immune tolerance mechanisms and prompted identification of molecular targets for therapy. However, PIRDs remain difficult to recognize due to incomplete penetrance of their diverse phenotype, which may cross organ systems and present to multiple clinical specialists prior to review by an immunologist. Control of immune dysregulation with immunosuppressive therapies must be balanced against the enhanced infective risk posed by the underlying defect and accumulated end-organ damage, posing a challenge to clinicians. Whilst allogeneic hematopoietic stem cell transplantation may correct the underlying immune defect, identification of appropriate patients and timing of transplant is difficult. The relatively recent description of many PIRDs and rarity of individual genetic entities that comprise this group means data on natural history, clinical progression, and treatment are limited, and so international collaboration will be needed to better delineate phenotypes and the impact of existing and potential therapies. This review explores pathophysiology, clinical features, current therapeutic strategies for PIRDs including cellular platforms, and future directions for research.

Immune checkpoints in T cells during oncogenic γ-herpesvirus infections

Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) are two persistent oncogenic γ-herpesviruses with an exclusive tropism for humans. They cause cancers of lymphocyte, epithelial and endothelial cell origin, such as Burkitt's and Hodgkin's lymphoma, primary effusion lymphoma, nasopharyngeal carcinoma, and Kaposi sarcoma. Mutations in immune-related genes but also adverse events during immune checkpoint inhibition in cancer patients have revealed molecular requirements for immune control of EBV and KSHV. These include costimulatory and coinhibitory receptors on T cells that are currently explored or already therapeutically targeted in tumor patients. This review discusses these co-receptors and their influence on EBV- and KSHV-associated diseases. The respective studies reveal surprising specificities of some of these receptors for immunity to these tumor viruses, benefits of their blockade for some but not other virus-associated diseases, and that EBV- and KSHV-specific immune control should be monitored during immune checkpoint inhibition to prevent adverse events that might be associated with their reactivation during treatment.

Do common infections trigger disease-onset or -severity in CTLA-4 insufficiency?

PURPOSE

Heterozygous mutations in CTLA4 lead to an inborn error of immunity characterized by immune dysregulation and immunodeficiency, known as CTLA-4 insufficiency. Cohort studies on CTLA4 mutation carriers showed a reduced penetrance (around 70%) and variable disease expressivity, suggesting the presence of modifying factors. It is well studied that infections can trigger autoimmunity in humans, especially in combination with a genetic predisposition.

METHODS

To investigate whether specific infections or the presence of specific persisting pathogens are associated with disease onset or severity in CTLA-4 insufficiency, we have examined the humoral immune response in 13 CTLA4 mutation carriers, seven without clinical manifestation and six with autoimmune manifestations, but without immunoglobulin replacement therapy against cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus 1/2 (HSV 1/2), parvovirus B19 and Toxoplasma gondii. Additionally, we have measured FcγRIII/CD16A activation by EBV-specific IgG antibodies to examine the functional capabilities of immunoglobulins produced by CTLA4 mutation carriers.

RESULTS

The seroprevalence between affected and unaffected CTLA4 mutation carriers did not differ significantly for the examined pathogens. Additionally, we show here that CTLA4 mutation carriers produce EBV-specific IgG, which are unimpaired in activating FcγRIII/CD16A.

CONCLUSIONS

Our results show that the investigated pathogens are very unlikely to trigger the disease onset in CTLA-4-insufficient individuals, and their prevalence is not correlated with disease severity or expressivity.

Clinical Courses of IKAROS and CTLA4 Deficiencies: A Systematic Literature Review and Retrospective Longitudinal Study

IKAROS and CTLA4 deficiencies are inborn errors of immunity and show similar clinical phenotypes, including hypogammaglobulinemia and autoimmune diseases (ADs). However, the differences in clinical features and pathogenesis of these are not fully understood. Therefore, we performed systematic literature reviews for IKAROS and CTLA4 deficiencies. The reviews suggested that patients with IKAROS deficiency develop AD earlier than hypogammaglobulinemia. However, no study assessed the detailed changes in clinical manifestations over time; this was likely due to the cross-sectional nature of the studies. Therefore, we conducted a retrospective longitudinal study on IKAROS and CTLA4 deficiencies in our cohort to evaluate the clinical course over time. In patients with IKAROS deficiency, AD and hypogammaglobulinemia often develop in that order, and AD often resolves before the onset of hypogammaglobulinemia; these observations were not found in patients with CTLA4 deficiency. Understanding this difference in the clinical course helps in the clinical management of both. Furthermore, our results suggest B- and T-cell-mediated ADs in patients with IKAROS and CTLA4 deficiencies, respectively.

Co-Stimulatory Molecules during Immune Control of Epstein Barr Virus Infection

The Epstein Barr virus (EBV) is one of the prominent human tumor viruses, and it is efficiently immune-controlled in most virus carriers. Cytotoxic lymphocytes strongly expand during symptomatic primary EBV infection and in preclinical in vivo models of this tumor virus infection. In these models and patients with primary immunodeficiencies, antibody blockade or deficiencies in certain molecular pathways lead to EBV-associated pathologies. In addition to T, NK, and NKT cell development, as well as their cytotoxic machinery, a set of co-stimulatory and co-inhibitory molecules was found to be required for EBV-specific immune control. The role of CD27/CD70, 4-1BB, SLAMs, NKG2D, CD16A/CD2, CTLA-4, and PD-1 will be discussed in this review. Some of these have just been recently identified as crucial for EBV-specific immune control, and for others, their important functions during protection were characterized in in vivo models of EBV infection and its immune control. These insights into the phenotype of cytotoxic lymphocytes that mediate the near-perfect immune control of EBV-associated malignancies might also guide immunotherapies against other tumors in the future.

Establishing the Molecular Diagnoses in a Cohort of 291 Patients With Predominantly Antibody Deficiency by Targeted Next-Generation Sequencing: Experience From a Monocentric Study

Predominantly antibody deficiencies (PAD) are a heterogeneous group of disorders characterized by dysfunctional antibody production, low immunoglobulin levels in serum and impaired vaccine responses. The clinical picture is variable, ranging from mild symptoms to severe complications, which may include autoimmunity, gastrointestinal disease, allergy, and malignancies. If left untreated, PAD patients are at risk of enduring disease progression, irreversible organ damage, and reduced life expectancy. A timely diagnosis has been shown to significantly improve disease prognosis. Here, we report on our experience using targeted gene panel sequencing by employing Agilent's HaloPlex or SureSelect and Illumina's MiSeq technologies in a cohort of 291 individuals who presented with low or absent immunoglobulin levels in combination with or without other clinical features. In total, we have detected over 57 novel or previously reported relevant mutations in ADA, ADA2, BTK, CTLA4, LRBA, NFKB1, NFKB2, PIK3CD, STAT3, and TNFRSF13B. Overall, a genetic diagnosis could be made in 24.7% of the investigated patients. The percentage of coverage for the targeted regions ranged from 90% to 98% in this study. Moreover, functional assays were performed on a defined group of the patients carrying candidate variants in CTLA4, LRBA, NFKB1 and BTK, which confirmed their deleterious effect on protein expression and/or function. This study reiterates that the immunological heterogeneity of predominantly antibody deficiencies may have a diverse genetic origin, although certain clinical features may hint towards a specific group of defects. Employing targeted sequencing panels proves to be a very time- and cost-efficient, yet reliable, method for the establishment of a genetic diagnosis in individuals with PAD. However, in case of negative panel results, or if functional testing reveals inconspicuous observations in patients with a clear indication for genetic testing, further work-up including whole exome or whole genome sequencing should be considered.

A sporadic case of CTLA4 haploinsufficiency manifesting as Epstein-Barr virus-positive diffuse large B-cell lymphoma

Cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) is a coinhibitory receptor that plays an essential role in maintaining immune system homeostasis by suppressing T-cell activation. We report a sporadic case of CTLA4 haploinsufficiency in a patient with Epstein–Barr virus-positive diffuse large B-cell lymphoma and subsequent benign lymphadenopathy. A missense mutation in exon 2 of the CTLA4 gene (c.251T>C, p.V84A) was found in the patient’s peripheral blood and buccal cell DNA, but not in her parents’ DNA. CTLA4 expression decreased in the peripheral regulatory T cells upon stimulation, whereas CTLA4 and PD-1-positive T cell subsets increased, possibly to compensate for the defective CTLA4 function. This case suggests that some adult lymphoma patients with no remarkable medical history have primary immune disorder. As immune-targeted therapies are now widely used for the treatment of malignancies, it is increasingly important to recognize the underlying primary immune disorders to properly manage the disease and avoid unexpected complications of immunotherapies.

Monogenic autoimmunity and infectious diseases: the double-edged sword of immune dysregulation

The study of monogenic autoimmune diseases has provided key insights into molecular mechanisms involved in development of autoimmunity and immune tolerance. It has also become clear that such inborn errors of immunity (IEIs) frequently present clinically not only with autoimmune diseases, but also frequently have increased susceptibility to infection. The genes associated with monogenic autoimmunity influence diverse functional pathways, and the resulting immune dysregulation also impacts the complex and coordinated immune response to pathogens, for example type I interferon and cytokine signaling, the complement pathway and proper differentiation of the immune response. The SARS-CoV-2 pandemic has highlighted how monogenic autoimmunity can increase risk for serious infection with the discovery of severe disease in patients with pre-existing antibodies to Type I IFNs. This review discusses recent insight into the relationship between monogenic autoimmunity and infectious diseases.

There is no gene for CVID - novel monogenetic causes for primary antibody deficiency

'There is no gene for fate' (citation from the movie 'GATTACA') - and there is no gene for CVID. Common Variable ImmunoDeficiency (CVID) is the most prevalent primary immunodeficiency in humans. CVID is characterized by an increased susceptibility to infections, hypogammaglobulinemia, reduced switched memory B cell numbers in peripheral blood and a defective response to vaccination, often complicated by autoimmune and autoinflammatory conditions. However, as soon as a genetic diagnosis has been made in a patient with CVID, the diagnosis must be changed to the respective genetic cause (www.esid.org). Therefore, there are genetic causes for primary antibody deficiencies, but not for CVID. Primary antibody deficiencies (PADs) are a heterogeneous group of disorders. Several attempts have been made to gain further insights into the pathogenesis of PAD, using unbiased approaches such as whole exome or genome sequencing. Today, in just about 35% of cases with PAD, monogenic mutations (including those in the gene TNFRSF13B) can be identified in a set of 68 genes [1^•]. These mutations occur either sporadically or are inherited and do explain an often complex phenotype. In our review, we not only discuss gene defects identified in PAD patients previously diagnosed with CVID and/or CVID-like disorders such as IKZF1, CTNNBL1, TNFSF13 and BACH2, but also genetic defects which were initially described in non-CVID patients but have later also been observed in patients with PAD such as PLCG2, PIK3CG, PMS2, RNF31, KMT2D, STAT3. We also included interesting genetic defects in which the pathophysiology suggests a close relation to other known defects of the adaptive immune response, such as DEF6, SAMD9 and SAMD9L, and hence a CVID-like phenotype may be observed in the future. However, alternative mechanisms most likely add to the development of an antibody-deficient phenotype, such as polygenic origins, epigenetic changes, and/or environmental factors.

Epstein Barr Virus and Autoimmune Responses in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease. Infections or infectious reactivation are potential triggers for initiation of autoimmunity and for SLE flares. Epstein-Barr virus (EBV) is gamma herpes virus that has been associated with several autoimmune diseases such as SLE, multiple sclerosis, Sjogren’s syndrome, and systemic sclerosis. In this review, we will discuss the recent advances regarding how EBV may contribute to immune dysregulation, and how these mechanisms may relate to SLE disease progression.

Expression of Immune Checkpoint Regulators, Cytotoxic T-Lymphocyte Antigen-4, and Programmed Death-Ligand 1 in Epstein-Barr Virus-associated Nasopharyngeal Carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is the most common cancer arising from the nasopharynx with a poor prognosis. Targeting immune checkpoint is one of the new promising lines in cancer treatment. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed death-ligand 1 (PD-L1) are immune checkpoints that regulate T-cell immune function.

AIM

This work aimed to assess the immunohistochemical expression of PD-L1 and CTLA-4 in NPC and their ability to predict survival and response therapy and to check their validity as immunotherapy targets. Twenty-six cases of NPC were studied by immunohistochemistry for PD-L1 and CTLA-4 and by nested polymerase chain reaction followed by DNA sequencing for the presence of EBNA-1 gene of Epstein-Barr virus (EBV). All investigated cases were diagnosed and treated in the Zagazig University Hospital in the period from August 2015 to July 2018. EBNA-1 gene was identified in 84.6% of the cases. Whereas the expression of PD-L1 was noted in 46.2% of all cases studied, 54.6% of EBV-associated NPCs were found to express PD-L1. There was a significant association between PD-L1 expression and the advanced stage of the tumor (P<0.001). CTLA-4 expression was observed in 88.4% of all NPC cases as cytoplasmic staining in both tumor cells and tumor-infiltrating lymphocytes. CTLA-4 expression in lymphocytes was associated with the presence of EBV. A significant association was detected between CTLA-4 and tumor-infiltrating lymphocyte expression on one side and the stage of the tumor on the other. High expression of CTLA-4 was significantly associated with disease progression and worse overall survival.

CONCLUSION

PD-L1 and CTLA-4 are adverse prognostic markers in NPC. The authors propose that targeted therapy against PD-L1 and CTLA-4 will be a hopeful therapy for cases of NPC with resistance to concurrent chemoradiation treatment in Egypt, especially EBV-associated cases.

CD8dimCD3+ lymphocytes in fever patients might be biomarkers of active EBV infection and exclusion indicator of T-LGLL

Background: Massive monoclonal or oligoclonal expansion of CD8⁺ T cells is a notable feature of primary infections of the Epstein-Barr virus (EBV). However, the clinical significance of this expansion is not clear. Results: An increase in the CD8^dimCD3⁺ lymphocyte subset in patients with active EBV infection was due to caspase-8-dependent apoptosis was found using flow cytometry in this study. The number of these cells was associated with the illness severity. Pan-T-cell antigen and receptor analyses were also compared in patients with active EBV infections and T-cell large granular lymphocytic leukemia to provide additional diagnostic information. Conclusion: The increase in CD8^dimCD3⁺ cells could be a biomarker of active EBV infection and an exclusion indicator of T-cell large granular lymphocytic leukemia with flow cytometric analysis.

Epstein-Barr Virus-Positive Mucocutaneous Ulcers Complicate Colitis Caused by Immune Checkpoint Regulator Therapy and Associate With Colon Perforation

BACKGROUND & AIMS

Cancer therapy with immune checkpoint inhibitors can cause colitis and colon perforation. We investigated whether infection with Epstein Barr virus (EBV) associates with development and severity of colitis in patients receiving immune checkpoint inhibitor therapies.

METHODS

We performed a retrospective analysis of fixed colon tissues from 16 patients (12 men, 4 women, median age, 69.5 y) with colitis after immune checkpoint inhibitor therapy (9 patients treated with anti-CTLA4, 3 patients treated with anti-PD1, and 4 patients received a combination). Ten tissue samples were biopsies and 6 were collected during resection (4 surgeries for colon perforation). Patients were treated between 2010 and 2018 in the United Kingdom. The tissues were analyzed by pathology, in situ hybridization (to detect EBV-encoded small RNAs [EBERs]), and immunohistochemistry. Clinical data were also collected.

RESULTS

Colon tissues from 4 of the 13 patients who received anti-CTLA4 (alone or in combination, 4 with colon perforation) had EBV-positive lymphoproliferations that manifested as florid ulcers associated with polymorphous infiltrates containing EBV-positive blasts (CD30+ or CD30-negative, CD20+, CD3-negative, and EBER+), plasma cells (CD138+, CD20-negative, and EBER+ or EBER-negative), and small B cells (CD20+, CD3-negative, and EBER+ or EBER-negative), consistent with EBV-positive mucocutaneous ulcers (EBVMCUs). In analyses of biopsies collected from 2 patients with EBVMCUs over multiple time points, we found that earlier biopsies had no or only a few EBV-positive cells, whereas 1 later biopsy had EBVMCU and co-infection with cytomegalovirus. EBVMCUs were associated with steroid-refractory colitis (100% of EBV-positive patients vs 12.5% of EBV-negative patients; P = .008) and colon perforation (100% of EBV-positive patients vs no EBV-negative patients; P = .001).

CONCLUSIONS

We found that colon tissues from 4/13 patients with colitis after anti-CTLA4 therapy (4/6 patients who underwent resection and 4/4 patients with colon perforation) contained EBVMCUs. EBVMCUs seem to arise secondarily in areas of inflamed colon due to immunosuppressive treatment for colitis. EBVMCUs are associated with steroid-refractory colitis and colon perforation.

Immunophenotyping of A20 haploinsufficiency by multicolor flow cytometry

Haploinsufficiency of A20 (HA20) causes inflammatory disease resembling Behçet's disease; many cases have been reported, including some that are complicated with autoimmune diseases. This study aims to clarify the immunophenotype of patients with HA20 by analyzing lymphocyte subsets using multicolor flow cytometry. The patients with HA20 previously diagnosed in a nationwide survey were compared by their cell subpopulations. In total, 27 parameters including regulatory T cells (Tregs), double-negative T cells (DNTs), and follicular helper T cells (TFHs) were analyzed and compared with the reference values in four age groups: 0-1, 2-6, 7-19, and ≥20 years. The Tregs of patients with HA20 tended to increase in tandem with age-matched controls at all ages. In addition, patients ≥20 years had increased DNTs compared with controls, whereas TFHs significantly increased in younger patients. In HA20 patients, the increase in DNTs and TFHs may contribute to the development of autoimmune diseases.

What did we learn from CTLA-4 insufficiency on the human immune system?

Cytotoxic-T-lymphocyte-antigen-4 (CTLA-4) is a negative immune regulator constitutively expressed on regulatory T (Treg) cells and upregulated on activated T cells. CTLA-4 inhibits T cell activation by various suppressive functions including competition with CD28, regulation of the inhibitory function of Treg cells, such as transendocytosis, and the control of adhesion and motility. Intrinsic CTLA-4 signaling has been controversially discussed, but so far no distinct signaling pathway has been identified. The CTLA-4-mediated Treg suppression plays an important role in the maintenance of peripheral tolerance and the prevention of autoimmune diseases. Human CTLA-4 insufficiency is caused by heterozygous germline mutations in CTLA4 and characterized by a complex immune dysregulation syndrome. Clinical studies on CTLA4 mutation carriers showed a reduced penetrance and variable expressivity, suggesting modifying factor(s). One hundred and forty-eight CTLA4 mutation carriers have been reported; patients showed hypogammaglobulinemia, recurrent infectious diseases, various autoimmune diseases, and lymphocytic infiltration into multiple organs. The CTLA-4 expression level in Treg cells was reduced, while the frequency of Treg cells was increased in CTLA-4-insufficient patients. The transendocytosis assay is a specific functional test for the assessment of newly identified CTLA4 gene variants. Immunoglobulin substitution, corticosteroids, immunosuppressive therapy, and targeted therapy such as with CTLA-4 fusion proteins and mechanistic target of rapamycin (mTOR) inhibitors were applied; patients with life-threatening, treatment-resistant symptoms underwent hematopoietic stem cell transplantation. The fact that in humans CTLA-4 insufficiency causes severe disease taught us that the amount of CTLA-4 molecules present in/on T cells matters for immune homeostasis. However, whether the pathology-causing activated T lymphocytes in CTLA-4-insufficient patients are antigen-specific is an unsolved question. CTLA-4, in addition, has a role in autoimmune diseases and cancer. Anti-CTLA-4 drugs are employed as checkpoint inhibitors to target various forms of cancer. Thus, clinical research on human CTLA-4 insufficiency might provide us a deeper understanding of the mechanism(s) of the CTLA-4 molecule and immune dysregulation disorders.

Increased Risk for Malignancies in 131 Affected CTLA4 Mutation Carriers

Background: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a negative immune regulator on the surface of T cells. In humans, heterozygous germline mutations in CTLA4 can cause an immune dysregulation syndrome. The phenotype comprises a broad spectrum of autoinflammatory, autoimmune, and immunodeficient features. An increased frequency of malignancies in primary immunodeficiencies is known, but their incidence in CTLA-4 insufficiency is unknown. Methods: Clinical manifestations and details of the clinical history were assessed in a worldwide cohort of 184 CTLA4 mutation carriers. Whenever a malignancy was reported, a malignancy-specific questionnaire was filled. Results: Among the 184 CTLA4 mutation carriers, 131 were considered affected, indicating a penetrance of 71.2%. We documented 17 malignancies, which amounts to a cancer prevalence of 12.9% in affected CTLA4 mutation carriers. There were ten lymphomas, five gastric cancers, one multiple myeloma, and one metastatic melanoma. Seven lymphomas and three gastric cancers were EBV-associated. Conclusion: Our findings demonstrate an elevated cancer risk for patients with CTLA-4 insufficiency. As more than half of the cancers were EBV-associated, the failure to control oncogenic viruses seems to be part of the CTLA-4-insufficient phenotype. Hence, lymphoproliferation and EBV viral load in blood should be carefully monitored, especially when immunosuppressing affected CTLA4 mutation carriers.