X-linked Chronic Granulomatous Disease Research Articles

In Vivo Hematopoietic Stem Cell Engineering Restores the Function of NADPH Enzyme Complex in X-Linked Chronic Granulomatous Disease Model Mice

In Vivo Hematopoietic Stem Cell Engineering Restores the Function of NADPH Enzyme Complex in X-Linked Chronic Granulomatous Disease Model Mice

High-fidelity PAMless base editing of hematopoietic stem cells to treat chronic granulomatous disease.

X-linked chronic granulomatous disease (X-CGD) is an inborn error of immunity (IEI) resulting from genetic mutations in the cytochrome b-245 beta chain (CYBB) gene. The applicability of base editors (BEs) to correct mutations that cause X-CGD is constrained by the requirement of Cas enzymes to recognize specific protospacer adjacent motifs (PAMs). Our recently engineered PAMless Cas enzyme, SpRY, can overcome the PAM limitation. However, the efficiency, specificity, and applicability of SpRY-based BEs to correct mutations in human hematopoietic stem and progenitor cells (HSPCs) have not been thoroughly examined. Here, we demonstrated that the adenine BE ABE8e-SpRY can access a range of target sites in HSPCs to correct mutations causative of X-CGD. For the prototypical X-CGD mutation CYBB c.676C>T, ABE8e-SpRY achieved up to 70% correction, reaching efficiencies greater than three-and-one-half times higher than previous CRISPR nuclease and donor template approaches. We profiled potential off-target DNA edits, transcriptome-wide RNA edits, and chromosomal perturbations in base-edited HSPCs, which together revealed minimal off-target or bystander edits. Edited alleles persisted after transplantation of the base-edited HSPCs into immunodeficient mice. Together, these investigational new drug-enabling studies demonstrated efficient and precise correction of an X-CGD mutation with PAMless BEs, supporting a first-in-human clinical trial (NCT06325709) and providing a potential blueprint for treatment of other IEI mutations.

High symptom burden in female X-linked chronic granulomatous disease carriers

High symptom burden in female X-linked chronic granulomatous disease carriers

Severe clinical phenotypes of heterozygous females with X-linked chronic granulomatous disease

Female X-linked chronic granulomatous disease (XL-CGD) carriers may develop severe clinical disease including infections with CGD-defining pathogens and inflammatory disorders. Similar to males with XL-CGD, female carriers warrant ongoing evaluation and prophylaxis where indicated.

Diagnosis of Chronic Granulomatous Disease: Strengths and Challenges in the Genomic Era.

Chronic granulomatous disease (CGD) is a group of rare primary inborn errors of immunity characterised by a defect in the phagocyte respiratory burst, which leads to severe and life-threatening infective and inflammatory complications. Despite recent advances in our understanding of the genetic and molecular pathophysiology of X-linked and autosomal recessive CGD, and growth in the availability of functional and genetic testing, there remain significant barriers to early and accurate diagnosis. In the current review, we provide an up-to-date summary of CGD pathophysiology, underpinning current methods of diagnostic testing for CGD and closely related disorders. We present an overview of the benefits of early diagnosis and when to suspect and test for CGD. We discuss current and historical methods for functional testing of NADPH oxidase activity, as well as assays for measuring protein expression of NADPH oxidase subunits. Lastly, we focus on genetic and genomic methods employed to diagnose CGD, including gene-targeted panels, comprehensive genomic testing and ancillary methods. Throughout, we highlight general limitations of testing, and caveats specific to interpretation of results in the context of CGD and related disorders, and provide an outlook for newborn screening and the future.

Genotype-phenotype correlations in chronic granulomatous disease: insights from a large national cohort

AbstractNeutrophils are the first line of defense against invading pathogens. Neutrophils execute and modulate immune responses by generating reactive oxygen species (ROS). Chronic granulomatous disease (CGD) is a primary immune deficiency disorder of phagocytes, caused by inherited mutations in the genes of the nicotinamide adenine dinucleotide phosphate reduced oxidase enzyme. These mutations lead to failure of ROS generation followed by recurrent bacterial and fungal infections, frequently associated with hyperinflammatory manifestations. We report a multicenter cumulative experience in diagnosing and treating patients with CGD. From 1986 to 2021, 2918 patients experiencing frequent infections were referred for neutrophil evaluation. Among them, 110 patients were diagnosed with CGD: 56 of Jewish ancestry, 48 of Arabic ancestry, and 6 of non-Jewish/non-Arabic ancestry. As opposed to other Western countries, the autosomal recessive (AR) CGD subtypes were predominant in Israel (71/110 patients). Thirty-nine patients had X-linked CGD, in most patients associated with severe infections (clinical severity score ≥3) and poor outcomes, presenting at a significantly earlier age than AR-CGD subtypes. The full spectrum of infections and hyperinflammatory manifestations is described. Six patients had hypomorphic mutations with significantly milder phenotype, clinical severity score ≤2, and better outcomes. Hematopoietic stem cell transplantation was implemented in 39 of 110 patients (35.5%). Successful engraftment was achieved in 92%, with 82% long-term survival and 71% full clinical recovery. CGD is a complex disorder requiring a multiprofessional team. Early identification of the genetic mutation is essential for prompt diagnosis, suitable management, and prevention.

50 Utilizing an Ethical Lens to Assess a Series of Patients With X-Linked CGD Who Did Not Undergo Hematopoietic Stem Cell Transplant

50 Utilizing an Ethical Lens to Assess a Series of Patients With X-Linked CGD Who Did Not Undergo Hematopoietic Stem Cell Transplant

In adult X-CGD patients, regulatory T cells are expanded while activated T cells display a NOX2-independent ROS increase

The X-linked chronic granulomatous disease (X-CGD), a rare genetic disease characterised by recurrent infections, is caused by mutations of NOX2. Significant proportions of X-CGD patients display signs of immune dysregulation. Regulatory T cells (Tregs) are CD4+T lymphocytes that expand in active inflammation and prevent autoimmune disorders. Here we asked whether X-CGD is associated to Treg dysfunctions in adult patients. To this aim, the frequency of Tregs was analysed through intracellular flow cytometry in a cohort of adult X-CGD patients, carriers and controls. We found that Tregs were significantly expanded and activated in blood of adult X-CGD patients, and this was associated with activation of conventional CD4+T cells (Tconvs). T cell activation was characterised by accumulation of intracellular ROS, not derived from NOX2 but likely produced by cellular metabolism. The higher TNF production by Tconvs in X-CGD patients might contribute to the expansion of Tregs through the TNFR2 receptor. In summary, our data indicate that Tregs expand in adult X-CGD in response to immune activation, and that the increase of NOX2-independent ROS content is a feature of activated T cells.

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.

Macrophage Activation Syndrome Secondary to Histoplasmosis in an Adult Female Carrier of X-linked Chronic Granulomatous Disease with Extreme Lyonization.

not applicable to a Letter to the Editor.

X-linked chronic granulomatous disease secondary to skewed X-chromosome inactivation in female patients.

Chronic granulomatous disease (CGD) is a heterogeneous primary immunodeficiency. X-linked (XL) CGD caused by gene defects of CYBB is the most prevalent type of CGD. We aim to understand the clinical and molecule features of XL-CGD secondary to skewed X-chromosome inactivation (XCI) in female. We retrospectively reviewed the medical records of a female patient diagnosed with XL-CGD. Flow cytometry was used to detect the respiratory burst function. After restriction enzyme digestion of DNA, XCI was calculated by detecting fluorescent PCR products with capillary electrophoresis. The previously published female XL-CGD cases secondary to skewed XCI was summarized. Clinical data were available for 15 female subjects. The median age of diagnosis was 16 years. Consistent with XL-CGD in males, infection was the most frequent manifestation in the female patients. Catalase-positive pathogens including Serratia marcescens and Staphylococcus aureus infections were the most common pathogens. Autoimmune/autoinflammation manifestations were observed in five patients. Dihydrorhodamine (DHR) assay showed that median %DHR+ values were 6.5% and the values varying with age were observed in 2 patients. All patients had a skewing XCI and there was no consistency between the daughter and carrier mother. Anti-infective treatment was effective in majority and there was no mortality reported in XL-CGD female patients to date. XL-CGD should not be neglected in female patients manifested as CGD phenotype and it is necessary to make periodic clinical evaluation of CGD female carriers as the neutrophil oxidative function may decline with aging and increase the risk for infection.

Carrier State of Chronic Granulomatous Disease Presented at Middle Age: A Case Report

Introduction: Chronic granulomatous disease (CGD) is the most common inherited defect of phagocytes. Although most female carriers of X-linked CGD have been considered to be unaffected, they may have similar problems to those of CGD patients. This study suggests that the CGD carrier state might be more complex than it was previously appreciated. Case Presentation: A sixty-year-old woman visited our hospital in June 2021 due to pneumonia and pleural effusion. Chest computed tomography scan revealed left lower lobe pneumonia and mediastinal lymphadenopathies. In July 2021, her symptoms (high-grade fever, chills, and hemoptysis) were initially attributed to a hydatid cyst. Therefore, she underwent a lobectomy, resulting in purulent drainage on the excision site on the skin, refractory to local and systemic treatments. The refractory and recurrent nature of the lesions led to the immunological evaluation, which was completely normal with a 100% nitroblue tetrazolium (NBT) and a dihydrorhodamine (DHR) of 278 (normal > 100). Further DHR123 flow cytometry investigations with multiple stimulants revealed a carrier state of CGD, which was relevant to her history of chronic complications. Conclusions: Adult patients with unusual manifestations suggestive of neutrophil function defects in adulthood should be evaluated for the CGD carrier state. In these cases, NBT alone may miss the diagnosis of CGD. In such cases, DHR testing with multiple stimulants may establish a robust diagnosis.

Myelodysplasia after clonal hematopoiesis with APOBEC3-mediated CYBB inactivation in retroviral gene therapy for X-CGD

Stem cell gene therapy using the MFGS-gp91phox retroviral vector was performed on a 27-year-old patient with X-linked chronic granulomatous disease (X-CGD) in 2014. The patient's refractory infections were resolved, whereas the oxidase-positive neutrophils disappeared within 6months. Thirty-two months after gene therapy, the patient developed myelodysplastic syndrome (MDS), and vector integration into the MECOM locus was identified in blast cells. The vector integration into MECOM was detectable in most myeloid cells at 12months after gene therapy. However, the patient exhibited normal hematopoiesis until the onset of MDS, suggesting that MECOM transactivation contributed to clonal hematopoiesis, and the blast transformation likely arose after the acquisition of additional genetic lesions. In whole-genome sequencing, the biallelic loss of the WT1 tumor suppressor gene, which occurred immediately before tumorigenesis, was identified as a potential candidate genetic alteration. The provirus CYBB cDNA in the blasts contained 108 G-to-A mutations exclusively in the coding strand, suggesting the occurrence of APOBEC3-mediated hypermutations during the transduction of CD34-positive cells. A hypermutation-mediated loss of oxidase activity may have facilitated the survival and proliferation of the clone with MECOM transactivation. Our data provide valuable insights into the complex mechanisms underlying the development of leukemia in X-CGD gene therapy.

Detailed characterisation of invasive aspergillosis in a murine model of X-linked chronic granulomatous disease shows new insights in infections caused by Aspergillus fumigatus versus Aspergillus nidulans.

Invasive aspergillosis (IA) is the most prevalent infectious complication in patients with chronic granulomatous disease (CGD). Yet, understanding of fungal pathogenesis in the CGD host remains limited, particularly with regards to A. nidulans infection. We have used a murine model of X-linked CGD to investigate how the pathogenesis of IA varies between A. fumigatus and A. nidulans, comparing infection in both X-linked CGD (gp91-/-) mice and their parent C57BL/6 (WT) mice. A 14-colour flow cytometry panel was used to assess the cell dynamics over the course of infection, with parallel assessment of pulmonary cytokine production and lung histology. We observed a lack of association between pulmonary pathology and infection outcome in gp91-/- mice, with no significant mortality in A. nidulans infected mice. An overwhelming and persistent neutrophil recruitment and IL-1 release in gp91-/- mice following both A. fumigatus and A. nidulans infection was observed, with divergent macrophage, dendritic cell and eosinophil responses and distinct cytokine profiles between the two infections. We have provided an in-depth characterisation of the immune response to pulmonary aspergillosis in an X-linked CGD murine model. This provides the first description of distinct pulmonary inflammatory environments in A. fumigatus and A. nidulans infection in X-linked CGD and identifies several new avenues for further research.

Allogeneic HSCT for Symptomatic Female X-linked Chronic Granulomatous Disease Carriers

X-linked chronic granulomatous disease (XL-CGD) is an inherited disorder of superoxide production, causing failure to generate the oxidative burst in phagocytes. It is characterized by invasive bacterial and fungal infections, inflammation, and chronic autoimmune disease. While XL-CGD carriers were previously assumed to be healthy, a range of clinical manifestations with significant morbidity have recently been described in a subgroup of carriers with impaired neutrophil oxidative burst due to skewed lyonization. Allogeneic hematopoietic stem cell transplantation (HSCT) is the standard curative treatment for CGD but has rarely been reported in individual symptomatic carriers to date. We undertook a retrospective international survey of outcome of HSCT for symptomatic XL-CGD carriers. Seven symptomatic female XL-CGD carriers aged 1–56 years underwent HSCT in four centers, indicated for severe and recurrent infection, colitis, and autoimmunity. Two patients died from transplant-related complications, following donor engraftment and restoration of oxidative burst. All surviving patients demonstrated resolution of their neutrophil oxidative burst defect with concordant reduction in infection and inflammatory symptoms and freedom from further immunosuppressive therapy. In conclusion, allogeneic HSCT may cure the phagocyte defect in symptomatic XL-CGD carriers and improve their recurrent and disabling infective and inflammatory symptoms but risks transplant-related complications.

Detection of CYBA Gene Expression by Reverse Transcription PCR as a Diagnostic Tool for Autosomal Recessive Chronic Granulomatous Disease in a Sample of Egyptian Children

Abstract Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency disease caused by functional impairment of the nicotinamide dinucleotide phosphate (NADPH) oxidase complex in neutrophilic granulocytes and monocytes, characterized by recurrent and severe infections, dysregulated inflammation, and autoimmunity. Approximately two-thirds of patients with CGD have defects in Cytochrome Bβ (CYBB), the X-linked gene encoding glycoprotein 91 phagocytic oxidase (gp91phox). Rarer autosomal recessive (AR) forms of CGD are caused by autosomal recessive mutations in CYBA genes encoding protein 22 phagocytic oxidase (p22phox). However, the incidence of autosomal recessive CGD can be higher than X-linked CGD in countries with high rates of consanguineous marriage. In the present study we aimed to diagnose the commonest AR-type of CGD by detection of CYBA gene expression using real time RT-PCR as a cheaper diagnostic method for CGD subtypes categorization among immunodeficient children. This case-control study was conducted on 15 children provisionally diagnosed as CGD patients with DHR stimulation index using phorbol myristate acetate (PMA) < 30% (Group I). The study also included 12 mothers and 8 fathers of the studied patients to detect the genetic mutations in carriers, if any (Group IIa and IIb respectively), and 14 apparently healthy children as a control group (Group III). We found that cases with a fold change of CYBA gene expression less than 0.6 were considered under-expressed. At this cut-off value, from our molecularly studied subjects 1 case and 2 mothers showed under-expression of CYBA gene. In conclusion, we could establish the diagnosis of AR-form of CGD, derives from defects in the CYBA gene, which encodes p22phox of the NADPH oxidase using real time RT-PCR, without the need to use complex and expensive methodologies such as northern blot, slot blot, or genomic DNA sequencing.

Molecular Challenges in the Diagnosis of X-Linked Chronic Granulomatous Disease: CNVs, Intronic Variants, Skewed X-Chromosome Inactivation, and Gonosomal Mosaicism.

Chronic granulomatous disease (CGD) is a prototypical inborn error of immunity affecting phagocytes, in which these cells are unable to produce reactive oxygen species. CGD is caused by defects in genes encoding subunits of the NADPH oxidase enzyme complex (CYBA, CYBB, CYBC1, NCF1, NCF2, NCF4); inflammatory responses are dysregulated, and patients are highly susceptible to recurrent severe bacterial and fungal infections. X-linked CGD (XL-CGD), caused by mutations in the CYBB gene, is the most common and severe form of CGD. In this study, we describe the analytical processes undertaken in 3 families affected with XL-CGD to illustrate several molecular challenges in the genetic diagnosis of this condition: in family 1, a girl with a heterozygous deletion of CYBB exon 13 and skewed X-chromosome inactivation (XCI); in family 2, a boy with a hemizygous deletion of CYBB exon 7, defining its consequences at the mRNA level; and in family 3, 2 boys with the same novel intronic variant in CYBB (c.1151 + 6T > A). The variant affected the splicing process, although a small fraction of wild-type mRNA was produced. Their mother was a heterozygous carrier, while their maternal grandmother was a carrier in form of gonosomal mosaicism. In summary, using a variety of techniques, including an NGS-based targeted gene panel and deep amplicon sequencing, copy number variation calling strategies, microarray-based comparative genomic hybridization, and cDNA analysis to define splicing defects and skewed XCI, we show how to face and solve some uncommon genetic mechanisms in the diagnosis of XL-CGD.

Novel mutations in CYBB Gene Cause X-linked chronic Granulomatous Disease in Pakistani patients

BackgroundChronic Granulomatous Disease (CGD) is a primary immunodeficiency that causes susceptibility to recurrent fungal and bacterial infections. The CYBB gene encodes gp91phox component of the Phagocytic Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and specifically, X-linked CGD is caused by mutations in the CYBB gene, located on the X chromosome. The aim of the study was to characterize functional and genetic mutations in X-linked CGD.MethodsFunctional analysis was conducted on the whole blood of seventeen male individuals who were suspected to have X-linked chronic granulomatous disease (CGD). Flow cytometry was employed to assess the capacity of NADPH oxidase, measuring both H2O2 production and gp91phox protein expression in neutrophils. Additionally, DNA Sanger sequencing was performed for genetic analysis. The pathogenicity of novel mutations was assessed by pathogenicity prediction tools.ResultAmong the seventeen patients evaluated, five patients (P1, P2, P3, P4, and P5) displayed impaired H2O2 production by their neutrophils upon stimulation with Phorbol myristate acetate (PMA), accompanied by abnormal gp91phox expression. DNA sequencing of the CYBB gene identified specific mutations in each patient. In P1 and P2 (previously reported cases), a hemizygous missense mutation, c.925G > A/p.E309K was identified. In P3 and P4 (novel cases), hemizygous nonsense mutations, c.216T > A/p.C72X were found. Lastly, in P5 (also a novel case), a hemizygous missense mutation, c.732T > G/p.C244W was detected. These mutations reside in exons 9,3 and 7 of the CYBB gene, respectively.ConclusionsThe current study contributes to the understanding of the clinical and genetic spectrum associated with X-linked chronic granulomatous disease (CGD). It highlights the significance of early diagnosis in CGD and emphasizes the importance of lifelong prophylaxis to prevent severe infections.

X-Linked Chronic Granulomatous Disease in a Female Carrier: A Management Challenge

Abstract Chronic granulomatous disease (CGD) is characterized by recurrent bacterial and fungal infections due to reduced nicotinamide adenine dinucleotide phosphate oxidase resulting in impaired production of reactive oxidant species, and aberrant inflammation. X-linked CGD (XL-CGD) is associated with a mutation in the CYBB gene. XL-CGD affects more males, although some females are affected affected due to skewed X-inactivation. Though management guidelines for CGD patients exist, they remain lacking for clinically affected XL-CGD female carriers. A 3 year old female with history of hematochezia, oral ulcers, and recurrent skin infections who presented with fevers and skin pustules. Pustule cultures were positive for B. cepacian, and colonoscopy was non-acute. Immunology had concern for XL-CGD with recent atypical infections and dihydrorhodamine (DHR) flow cytometry was abnormal, 17.7% (normal greater than 95%). DHR 2 months later showed 13% activation. Genetic testing showed a CYBB, c.45+2dup (intronic), heterozygous, VUS, gene mutation affecting the splice site, associated with XL-CGD, and a NOD2, c.3019dup, heterozygous, with a 2–4 fold increased risk for Crohn’s disease. She was started on bacterial prophylaxis only. She is awaiting gp91phox expression for gene sequencing. XL-CGD carriers can be at higher risk for infections, and risk is inversely correlated with %DHR neutrophil counts, but only clinically apparent with %DHR less than 20%, and more as levels are less than 10%. Though our patient was started on Bactrim prophylaxis with her %DHR less than 20%, there remains the question of when and if she should be started on anti-fungal prophylaxis. There remain no clear guidelines on the management of XL-CGD carriers.

Use of Interferon Gamma in Female Carriers of X-linked Chronic Granulomatous Disease

IntroductionChronic granulomatous disease (CGD) is characterized by increased frequency and severity of certain infections, autoimmune disease, and hyperinflammation. Heterozygous female carriers of X-linked CGD may experience similar symptoms. Guidance for management of female carriers is limited. We describe the use of interferon gamma (IFNγ) in X-linked CGD carriers. MethodsA multi-center retrospective chart review identified 4 carriers of X-linked CGD who received prophylaxis with IFNγ. Results of dihydrorhodamine (DHR) assay, infections and autoinflammatory features were documented and adverse events (AE) related to IFNγ were recorded. ResultsFour females (mean age 40 [range 0.5–71] years) received IFNγ (75–100 µg 3 times per week via subcutaneous injection) for a mean duration of 43 (range 16–63) months. Infections prior to the start of IFNγ included sepsis/bacteremia, pneumonia, skin and soft tissue infection, osteomyelitis, and gastroenteritis with CGD-associated pathogens including Serratia marscescens, Burkholderia cepacia, Nocardia spp, and methicillin-resistant Staphylococcus aureus (MRSA). Inflammatory complications (some in more than one subject) included dermatologic (pyoderma gangrenosum [n = 1], unspecified dermatitis [n = 2]), rheumatologic (arthritis [n = 1], Raynaud's syndrome [n = 1]), and gastrointestinal (inflammatory diarrhea [n = 1], Barrett's esophagus [n = 1]). Each carrier exhibited two populations of neutrophil oxidative burst. The populations expressing DHR were as follows: 0.08, 1, 3, and 10.8 +DHR%. Antibacterial prophylaxis was administered in all 4 subjects, and antifungal prophylaxis in 3 subjects. Pre-medications were not administered, and AE associated with IFNγ were mild or moderate in 3 of 4 subjects (one subject had no AE) and did not result in any treatment discontinuations. One patient discontinued prophylaxis with IFNγ after correction of CGD following hematopoietic stem cell transplant. The average length of follow-up since starting IFNγ was 38 months. While on IFNγ therapy, one patient developed atypical mycobacterial and cytomegalovirus pneumonia and MRSA chronic osteomyelitis thought related to poor compliance, while another developed Serratia olecranon abscess/. None developed autoimmune/inflammatory disease while on therapy. ConclusionsThis is the first report to our knowledge of IFNγ use for prophylaxis in carriers of X-linked CGD. IFNγ was well tolerated, and should be considered for prophylaxis in female carriers with very low neutrophil oxidative burst or frequent or severe CGD-associated infections.