Heterozygous SERPINA1 Defects and Their Impact on Clinical Manifestations of Patients with Predominantly Antibody Deficiencies.

Patients with predominantly antibody deficiencies (PADs) display hypogammaglobulinemia with a high prevalence of infections, along with autoimmune manifestations, benign and malignant lymphoproliferation and granulomatous disease. It is noteworthy that PAD patients, even those with defects in the same causative genes, display a variable clinical phenotype, suggesting that additional genetic polymorphisms, located in either immune-related or non-immune-related genes, may affect their clinical and laboratory phenotype. In this context, we analyzed 80 PAD patients, including 70 with common variable immunodeficiency (CVID) for SERPINA1 defects, in order to investigate the possible contribution to PAD clinical phenotype. Ten CVID patients carried heterozygous pathogenic SERPINA1 defects with normal alpha-1 antitrypsin levels. Interestingly, the presence of the Z allele (rs28929474), which was found in three patients, was significantly associated with liver disease; hepatic complications were also observed in patients carrying the p.Leu23Gln (rs1379209512) and the p.Phe76del (rs775982338) alleles. Conversely, no correlation of SERPINA1 defective variants with respiratory complications was observed, although patients with pathogenic variants exhibit a reduced probability of developing autoimmune diseases. Therefore, we recommend SERPINA1 genetic analysis in PAD in order to identify patients with a higher risk for liver disease.

Fluoxetine Successfully Treats Intracranial Enterovirus E18 Infection in a Patient with CD79a Deficiency Arising from Segmental Uniparental Disomy of Chromosome 19.

The pre BCR complex plays a crucial role in B cell production, and its successful expression marks the B cell differentiation from the pro-B to pre-B. The CD79a and CD79b mutations, encoding Igα and Igß respectively, have been identified as the cause of autosomal recessive agammaglobulinemia (ARA). Here, we present a case of a patient with a homozygous CD79a mutation, exhibiting recurrent respiratory infections, diarrhea, growth and development delay, unique facial abnormalities and microcephaly, as well as neurological symptoms including tethered spinal cord, sacral canal cyst, and chronic enteroviral E18 meningitis. Complete blockade of the early B cell development in the bone marrow of the patient results in the absence of peripheral circulating mature B cells. Whole exome sequencing revealed a Loss of Heterozygosity (LOH) of approximately 19.20Mb containing CD79a on chromosome 19 in the patient. This is the first case of a homozygous CD79a mutation caused by segmental uniparental diploid (UPD). Another key outcome of this study is the effective management of long-term chronic enteroviral meningitis using a combination of intravenous immunoglobulin (IVIG) and fluoxetine. This approach offers compelling evidence of fluoxetine's utility in treating enteroviral meningitis, particularly in immunocompromised patients.

A case of T-cell acute lymphoblastic leukemia in retroviral gene therapy for ADA-SCID.

Hematopoietic stem cell gene therapy (GT) using a γ-retroviral vector (γ-RV) is an effective treatment for Severe Combined Immunodeficiency due to Adenosine Deaminase deficiency. Here, we describe a case of GT-related T-cell acute lymphoblastic leukemia (T-ALL) that developed 4.7 years after treatment. The patient underwent chemotherapy and haploidentical transplantation and is currently in remission. Blast cells contain a single vector insertion activating the LIM-only protein 2 (LMO2) proto-oncogene, confirmed by physical interaction, and low Adenosine Deaminase (ADA) activity resulting from methylation of viral promoter. The insertion is detected years before T-ALL in multiple lineages, suggesting that further hits occurred in a thymic progenitor. Blast cells contain known and novel somatic mutations as well as germline mutations which may have contributed to transformation. Before T-ALL onset, the insertion profile is similar to those of other ADA-deficient patients. The limited incidence of vector-related adverse events in ADA-deficiency compared to other γ-RV GT trials could be explained by differences in transgenes, background disease and patient's specific factors.

B-cells absence in patients diagnosed as inborn errors of immunity: a registry-based study.

Hypogammaglobulinemia without B-cells is a subgroup of inborn errors of immunity (IEI) which is characterized by a significant decline in all serum immunoglobulin isotypes, coupled with a pronounced reduction or absence of B-cells. Approximately 80 to 90% of individuals exhibit genetic variations in Bruton's agammaglobulinemia tyrosine kinase (BTK), whereas a minority of cases, around 5-10%, are autosomal recessive agammaglobulinemia (ARA). Very few cases are grouped into distinct subcategories. We evaluated phenotypically and genetically 27 patients from 13 distinct families with hypogammaglobinemia and no B-cells. Genetic analysis was performed via whole-exome and Sanger sequencing. The most prevalent genetic cause was mutations in BTK. Three novel mutations in the BTK gene include c.115 T > C (p. Tyr39His), c.685-686insTTAC (p.Asn229llefs5), and c.163delT (p.Ser55GlnfsTer2). Our three ARA patients include a novel homozygous stop-gain mutation in the immunoglobulin heavy constant Mu chain (IGHM) gene, a novel frameshift mutation of the B-cell antigen receptor complex-associated protein (CD79A) gene, a novel bi-allelic stop-gain mutation in the transcription factor 3 (TCF3) gene. Three patients with agammaglobulinemia have an autosomal dominant inheritance pattern, which includes a missense variant in PIK3CD, a novel missense variant in PIK3R1 and a homozygous silent mutation in the phosphoinositide-3-kinase regulatory subunit (RASGRP1) gene. This study broadens the genetic spectrum of hypogammaglobulinemia without B-cells and presented a few novel variants within the Iranian community, which may also have implications in other Middle Eastern populations. Notably, disease control was better in the second affected family member in families with multiple cases.

IgA nephropathy in a child with X-linked agammaglobulinemia: a case report.

BACKGROUND: X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disease caused by mutations in the Bruton tyrosine kinase (BTK) gene. Individuals diagnosed with XLA are at an increased risk of developing autoimmune diseases. However, renal involvement are rare in cases of XLA. CASE PRESENTATION: In this report, we discussed a specific case involving a 6-year-old boy with XLA who experienced recurrent upper respiratory tract infections since the age of one. He presented with symptoms of hematuria and proteinuria, and renal pathology confirmed the presence of immunoglobulin (Ig) A nephropathy. Treatment comprised glucocorticoids, mycophenolate mofetil, and intermittent intravenous immunoglobulin replacement therapy. Consequently, there was a remission of proteinuria and a partial improvement in hematuria. CONCLUSIONS: In this study, we describe the first case of IgA nephropathy associated with XLA. This is an interesting phenotype found in XLA, and it provides valuable insights into the process of autoimmunity and the regulation of immune function in individuals with XLA. Based on our findings, we recommend the evaluation of immunoglobulin levels in patients diagnosed with IgA nephropathy.

Case report: Rapidly progressive neurocognitive disorder with a fatal outcome in a patient with PU.1 mutated agammaglobulinemia.

Introduction: PU.1-mutated agammaglobulinemia (PU.MA) represents a recently described autosomal-dominant form of agammaglobulinemia caused by mutation of the SPI1 gene. This gene codes for PU.1 pioneer transcription factor important for the maturation of monocytes, B lymphocytes, and conventional dendritic cells. Only six cases with PU.MA, presenting with chronic sinopulmonary and systemic enteroviral infections, have been previously described. Accumulating literature evidence suggests a possible relationship between SPI1 mutation, microglial phagocytic dysfunction, and the development of Alzheimer's disease (AD). Case description: We present a Caucasian female patient born from a non-consanguineous marriage, who was diagnosed with agammaglobulinemia at the age of 15 years when the immunoglobulin replacement therapy was started. During the following seventeen years, she was treated for recurrent respiratory and intestinal infections. At the age of 33 years, the diagnosis of celiac-like disease was established. Five years later progressive cognitive deterioration, unstable gait, speech disturbances, and behavioral changes developed. Comprehensive microbiological investigations were negative, excluding possible infective etiology. Brain MRI, 18FDG-PET-CT, and neuropsychological testing were suggestive for a diagnosis of a frontal variant of AD. Clinical exome sequencing revealed the presence of a novel frameshift heterozygous variant c.441dup in exon 4 of the SPI1 gene. Despite intensive therapy, the patient passed away a few months after the onset of the first neurological symptoms. Conclusion: We describe the first case of PU.MA patient presenting with a rapidly progressive neurocognitive deterioration. The possible role of microglial dysfunction in patients with SPI1 mutation could explain their susceptibility to neurodegenerative diseases thus highlighting the importance of genetic testing in patients with inborn errors of immunity. Since PU.MA represents a newly described form of agammaglobulinemia, our case expands the spectrum of manifestations associated with SPI1 mutation.

X-Linked Lymphoproliferative Syndrome: A Spectrum of Clinical and Immunological Profile and Novel Pathogenic Variants from Chandigarh, India.

INTRODUCTION: X-linked lymphoproliferative syndrome (XLP) is a rare primary immune deficiency. Two types of XLP have been described: XLP-1 and XLP-2. METHODS: We found 7 patients with XLP (3 had XLP-1 and 4 had XLP-2) after reviewing the data from Pediatric Immunodeficiency Clinic from 1997 to 2021. RESULTS: Mean age at diagnosis was 3.8 years, and mean delay in diagnosis was 2.6 years. Five patients had recurrent episodes of infections. Four patients developed at least one episode of hemophagocytic lymphohistiocytosis (HLH) (2 with XLP-1 and 2 with XLP-2). Of these, 2 had recurrent HLH (both with XLP-2). Epstein-Barr virus (EBV) infection was detected in 2 (1 with XLP-1 and 1 with XLP-2). Both these patients had HLH. One child with XLP-2 had inflammatory bowel disease. Hypogammaglobulinemia was seen in 3 (2 with XLP-1 and 1 with XLP-2). Genetic analysis showed previously reported variants in 5, while 2 had novel variants (one in exon 7 of XIAP gene [c.1370dup p.Asn457Lysfs Ter16] and other had splice site variant in intron 1 of SH2D1A gene [c.138-2_138-1insG]). Episodes of HLH were managed with intravenous immunoglobulin (IVIg), methylprednisolone, oral prednisolone, cyclosporine, and rituximab. Inflammatory bowel disease was managed using oral prednisolone and azathioprine. One patient underwent haploidentical hematopoietic stem cell transplantation. One child with XLP-2 and WAS died because of fulminant pneumonia. DISCUSSION/CONCLUSIONS: XLP should be considered as a strong possibility in any patient with features of HLH, repeated infections with hypogammaglobulinemia, persistent EBV infection, and early-onset IBD.

What a Clinician Needs to Know About Genome Editing: Status and Opportunities for Inborn Errors of Immunity.

During the past 20 years, gene editing has emerged as a novel form of gene therapy. Since the publication of the first potentially therapeutic gene editing platform for genetic disorders, increasingly sophisticated editing technologies have been developed. As with viral vector-mediated gene addition, inborn errors of immunity are excellent candidate diseases for a corrective autologous hematopoietic stem cell gene editing strategy. Research on gene editing for inborn errors of immunity is still entirely preclinical, with no trials yet underway. However, with editing techniques maturing, scientists are investigating this novel form of gene therapy in context of an increasing number of inborn errors of immunity. Here, we present an overview of these studies and the recent progress moving these technologies closer to clinical benefit.

Gene regulation in inborn errors of immunity: Implications for gene therapy design and efficacy.

Inborn errors of immunity (IEI) present a unique paradigm in the realm of gene therapy, emphasizing the need for precision in therapeutic design. As gene therapy transitions from broad-spectrum gene addition to careful modification of specific genes, the enduring safety and effectiveness of these therapies in clinical settings have become crucial. This review discusses the significance of IEIs as foundational models for pioneering and refining precision medicine. We explore the capabilities of gene addition and gene correction platforms in modifying the DNA sequence of primary cells tailored for IEIs. The review uses four specific IEIs to highlight key issues in gene therapy strategies: X-linked agammaglobulinemia (XLA), X-linked chronic granulomatous disease (X-CGD), X-linked hyper IgM syndrome (XHIGM), and immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX). We detail the regulatory intricacies and therapeutic innovations for each disorder, incorporating insights from relevant clinical trials. For most IEIs, regulated expression is a vital aspect of the underlying biology, and we discuss the importance of endogenous regulation in developing gene therapy strategies.

Biallelic Cys141Tyr variant of SEL1L is associated with neurodevelopmental disorders, agammaglobulinemia, and premature death.

Suppressor of lin-12-like-HMG-CoA reductase degradation 1 (SEL1L-HRD1) ER-associated degradation (ERAD) plays a critical role in many physiological processes in mice, including immunity, water homeostasis, and energy metabolism; however, its relevance and importance in humans remain unclear, as no disease variant has been identified. Here, we report a biallelic SEL1L variant (p. Cys141Tyr) in 5 patients from a consanguineous Slovakian family. These patients presented with not only ERAD-associated neurodevelopmental disorders with onset in infancy (ENDI) syndromes, but infantile-onset agammaglobulinemia with no mature B cells, resulting in frequent infections and early death. This variant disrupted the formation of a disulfide bond in the luminal fibronectin II domain of SEL1L, largely abolishing the function of the SEL1L-HRD1 ERAD complex in part via proteasomal-mediated self destruction by HRD1. This study reports a disease entity termed ENDI-agammaglobulinemia (ENDI-A) syndrome and establishes an inverse correlation between SEL1L-HRD1 ERAD functionality and disease severity in humans.

Enhanced CD19 activity in B cells contributes to immunodeficiency in mice deficient in the ICF syndrome gene Zbtb24.

Immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome is a rare autosomal recessive disorder characterized by DNA hypomethylation and antibody deficiency. It is caused by mutations in DNMT3B, ZBTB24, CDCA7, or HELLS. While progress has been made in elucidating the roles of these genes in regulating DNA methylation, little is known about the pathogenesis of the life-threatening hypogammaglobulinemia phenotype. Here, we show that mice deficient in Zbtb24 in the hematopoietic lineage recapitulate the major clinical features of patients with ICF syndrome. Specifically, Vav-Cre-mediated ablation of Zbtb24 does not affect lymphocyte development but results in reduced plasma cells and low levels of IgM, IgG1, and IgA. Zbtb24-deficient mice are hyper and hypo-responsive to T-dependent and T-independent type 2 antigens, respectively, and marginal zone B-cell activation is impaired. Mechanistically, Zbtb24-deficient B cells show severe loss of DNA methylation in the promoter region of Il5ra (interleukin-5 receptor subunit alpha), and Il5ra derepression leads to elevated CD19 phosphorylation. Heterozygous disruption of Cd19 can revert the hypogammaglobulinemia phenotype of Zbtb24-deficient mice. Our results suggest the potential role of enhanced CD19 activity in immunodeficiency in ICF syndrome.

Transcriptome profiling of regulatory T cells from children with transient hypogammaglobulinemia of infancy.

Transient hypogammaglobulinemia of infancy (THI) is one of the most common forms of hypogammaglobulinemia in the early childhood. THI is usually associated with chronic, recurrent bacterial and viral infections, life-threatening in some cases, yet its pathogenesis is still largely unknown. As our previous findings indicated the possible role of Treg cells in the pathomechanism of THI, the aim of the current study was to investigate gene expression profile of Treg cells isolated from THI patients. The transcriptome-wide gene profiling was performed using microarray technology on THI patients in two time-points: during (THI-1), and in resolution phase (THI-2) of hypogammaglobulinemia. As a result, a total of 1086 genes were differentially expressed in THI-1 patients, when compared to THI-2 as well as control group. Among them, 931 were up- and 155 downregulated, and part of them encodes genes important for Treg lymphocyte biology and function, i.e. transcription factors/cofactors that regulate FOXP3 expression. Thus, we postulate that Treg cells isolated from THI patients during hypogammaglobulinemia display enhanced suppressor transcriptome signature. Treg expression profile of THI children after normalization of Ig levels largely resembles the results obtained in healthy control group, suggesting THI Treg transcriptome seems to return to that observed in healthy children. Taken together, we suggest that THI pathomechanism is associated not only with transiently elevated Treg cell numbers, but also with their enhanced regulatory/inhibitory functions. These findings expand our knowledge of human Treg cells and may be useful for the future diagnosis or management of THI.

Investigation of a synonymous mutation in Btk in a patient with agammaglobulinemia: A case report.

BACKGROUND: X-linked agammaglobulinemia (XLA) is the most common form of agammaglobulinemia and is caused by mutations in Btk, which encodes Bruton tyrosine kinase (BTK). CASE DESCRIPTION: We describe a 36-year-old male who presented as an infant with hypogammaglobulinemia and sinopulmonary infections and was initially diagnosed with common variable immunodeficiency. Genetic testing showed he was hemizygous for Btk c.240G > A. This synonymous variant affecting the last nucleotide of exon 3 leads to aberrant splicing of most but not all mRNA transcripts. CONCLUSION: We demonstrated reduced BTK protein expression confirming the pathogenicity of the variant and related our findings to genotype-phenotype relationship studies ina XLA caused by synonymous mutations.

Clinical features and mutational analysis of X-linked agammaglobulinemia patients in Malaysia.

Background: Bruton's tyrosine kinase (BTK) is a cytoplasmic protein involved in the B cell development. X-linked agammaglobulinemia (XLA) is caused by mutation in the BTK gene, which results in very low or absent B cells. Affected males have markedly reduced immunoglobulin levels, which render them susceptible to recurrent and severe bacterial infections. Methods: Patients suspected with X-linked agammaglobulinemia were enrolled during the period of 2010-2018. Clinical summary, and immunological profiles of these patients were recorded. Peripheral blood samples were collected for monocyte BTK protein expression detection and BTK genetic analysis. The medical records between January 2020 and June 2023 were reviewed to investigate COVID-19 in XLA. Results: Twenty-two patients (from 16 unrelated families) were molecularly diagnosed as XLA. Genetic testing revealed fifteen distinct mutations, including four splicing mutations, four missense mutations, three nonsense mutations, three short deletions, and one large indel mutation. These mutations scattered throughout the BTK gene and mostly affected the kinase domain. All mutations including five novel mutations were predicted to be pathogenic or deleterious by in silico prediction tools. Genetic testing confirmed that eleven mothers and seven sisters were carriers for the disease, while three mutations were de novo. Flow cytometric analysis showed that thirteen patients had minimal BTK expression (0-15%) while eight patients had reduced BTK expression (16-64%). One patient was not tested for monocyte BTK expression due to insufficient sample. Pneumonia (n=13) was the most common manifestation, while Pseudomonas aeruginosa was the most frequently isolated pathogen from the patients (n=4). Mild or asymptomatic COVID-19 was reported in four patients. Conclusion: This report provides the first overview of demographic, clinical, immunological and genetic data of XLA in Malaysia. The combination of flow cytometric assessment and BTK genetic analysis provides a definitive diagnosis for XLA patients, especially with atypical clinical presentation. In addition, it may also allow carrier detection and assist in genetic counselling and prenatal diagnosis.

Antibody Deficiency in Patients with Biallelic KARS1 Mutations.

Biallelic KARS1 mutations cause KARS-related diseases, a rare syndromic condition encompassing central and peripheral nervous system impairment, heart and liver disease, and deafness. KARS1 encodes the t-RNA synthase of lysine, an aminoacyl-tRNA synthetase, involved in different physiological mechanisms (such as angiogenesis, post-translational modifications, translation initiation, autophagy and mitochondrial function). Although patients with immune-hematological abnormalities have been individually described, results have not been collectively discussed and functional studies investigating how KARS1 mutations affect B cells have not been performed. Here, we describe one patient with severe developmental delay, sensoneurinal deafness, acute disseminated encephalomyelitis, hypogammaglobulinemia and recurrent infections. Pathogenic biallelic KARS1 variants (Phe291Val/ Pro499Leu) were associated with impaired B cell metabolism (decreased mitochondrial numbers and activity). All published cases of KARS-related diseases were identified. The corresponding authors and researchers involved in the diagnosis of inborn errors of immunity or genetic syndromes were contacted to obtain up-to-date clinical and immunological information. Seventeen patients with KARS-related diseases were identified. Recurrent/severe infections (9/17) and B cell abnormalities (either B cell lymphopenia [3/9], hypogammaglobulinemia [either IgG, IgA or IgM; 6/15] or impaired vaccine responses [4/7]) were frequently reported. Immunoglobulin replacement therapy was given in five patients. Full immunological assessment is warranted in these patients, who may require detailed investigation and specific supportive treatment.

A novel mutation in DNMT3B gene causing ICF1 syndrome in an infant with refractory thrombocytopenia.

BACKGROUND: ICF syndrome is a rare autosomal recessive condition characterized by immunodeficiency, centromeric instability, and facial abnormalities. It is a clinical condition that depends on the mutation of a few particular genes and is caused by methylation disruption in chromosomes 1, 9, and 16 to varying degrees. CASE PRESENTATION: The 9-months old, female patient was admitted to our clinic for treatment-resistant thrombocytopenia, chronic diarrhea and sepsis. Immunological investigations revealed agammaglobulinemia. In the genetic analysis by NGS of the patient, who had dysmorphic facial findings as well as a history of parental consanguinity, it was determined that she had a novel mutation in the DNMT3B gene, which is one of the responsible genes of ICF, as homozygous. The patient, who was started on regular immunoglobulin replacement therapy and antibiotic therapy, was referred to a center with a stem cell transplant unit to continue her follow-up. CONCLUSIONS: Although autoimmunity has not been commonly reported in previous studies in ICF syndrome, which has a varied clinical presentation, a homozygous mutation in the DNMT3B gene was discovered in a 9-month-old patient with refractory thrombocytopenia and agammaglobulinemia. Examining the literature reveals that this mutation is a novel mutation.

First report of Wilson disease and Bruton agammaglobulinemia in the same patient caused by new mutations in ATP7B and BTK genes.

INTRODUCTION: Wilson disease is characterized by an alteration in copper metabolism that causes its accumulation in different tissues. Its diagnosis is established by the combination of clinical manifestations and paraclinical and genetic studies. Bruton agammaglobulinemia is an X-linked recessive hereditary disease belonging to the group of primary immunodeficiencies and is produced by mutation in the Bruton tyrosine kinase (BTK) gene. CASE REPORT: A 14-year-old Colombian patient with clinical characteristics of Bruton agammaglobulinemia presented with liver disease and clinically and molecularly diagnosed with Wilson disease. DISCUSSION: Bruton agammaglobulinemia and Wilson disease are considered rare diseases because of their low prevalence. We report for the first time a pediatric patient from southwestern Colombia presenting with both entities, and diagnosed clinically and molecularly, an association so far not reported in the literature.