Hematopoietic stem cell gene editing rescues B-cell development in X-linked agammaglobulinemia

BACKGROUND

X-linked agammaglobulinemia (XLA) is an inborn error of immunity that renders boys susceptible to life-threatening infections due to loss of mature B cells and circulating immunoglobulins. It is caused by defects in the gene encoding the Bruton tyrosine kinase (BTK) that mediates the maturation of B cells in the bone marrow and their activation in the periphery. This paper reports on a gene editing protocol to achieve "knock-in" of a therapeutic BTK cassette in hematopoietic stem and progenitor cells (HSPCs) as a treatment for XLA.

METHODS

To rescue BTK expression, this study employed a clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 system that creates a DNA double-strand break in an early exon of the BTK locus and an adeno-associated virus 6 virus that carries the donor template for homology-directed repair. The investigators evaluated the efficacy of the gene editing approach in HSPCs from patients with XLA that were cultured in vitro under B-cell differentiation conditions or that were transplanted in immunodeficient mice to study B-cell output in vivo.

RESULTS

A (feeder-free) B-cell differentiation protocol was successfully applied to blood-mobilized HSPCs to reproduce in vitro the defects in B-cell maturation observed in patients with XLA. Using this system, the investigators could show the rescue of B-cell maturation by gene editing. Transplantation of edited XLA HSPCs into immunodeficient mice led to restoration of the human B-cell lineage compartment in the bone marrow and immunoglobulin production in the periphery.

CONCLUSIONS

Gene editing efficiencies above 30% could be consistently achieved in human HSPCs. Given the potential selective advantage of corrected cells, as suggested by skewed X-linked inactivation in carrier females and by competitive repopulating experiments in mouse models, this work demonstrates the potential of this strategy as a future definitive therapy for XLA.

Climatic and calf-related risk factors associated with failure of transfer of passive immunity in Holstein calves in a hot environment

This retrospective observational study aimed to assess the effect of temperature-humidity index (THI) at calving and in the last trimester of pregnancy and calve-related factors affecting passive transfer of maternal immunoglobulin using Brix refractometry in Holstein calves. Blood samples from 4411 Holstein calves from a single large dairy farm in spring 2022 were used. A subset of data containing 6318 calvings was used to determine the effect of climatic conditions on the occurrence of agammaglobulinemia. Risk factors predictive of failure of passive transfer (FPT) were calculated using multiple logistic models. Females were 1.4 times more likely not to have FPT (56%; Brix% > 8 equivalent to ≥ 10 g/L IgG) than males (47.2%). Calves born as singles increased the likelihood of not presenting FPT (52.6%) than calves born as twins (42.9%). Calves from cows with no dystocic delivery had a lower risk for FPT (odds ratio = 2.3) than calves from cows with dystocia. Agammaglobulinemia was 1.5 and 1.8 times more likely to occur in calves with THI ≥ 80 and ≥ 82 in the last trimester of gestation and at calving, respectively, than in calves not experiencing heat stress. Agammaglobulinemia was twice as likely to occur in male than in female calves. Calves with birth weight ≥ 37 kg and gestation length ≥ 275 kg were less likely to present agammaglobulinemia than lighter calves and calves with shorter gestation periods. This study raises questions for management practices in Holstein calves undergoing in utero heat stress and around calving to avoid agammaglobulinemia.

Metagenomics assists in the diagnosis of a refractory, culture-negative pyoderma gangrenosum-like ulcer caused by Helicobacter cinaedi in a patient with primary agammaglobulinemia

Helicobacter cinaedi is known to cause various infections in immunocompromised hosts ranging from skin lesions to disseminated septicemia. Identification of H. cinaedi is difficult through conventional identification methods due to its fastidious nature. We reported a refractory and culture-negative pyoderma gangrenosum-like ulcer caused by H. cinaedi in a patient with primary agammaglobulinemia. Metagenomic next-generation sequencing (mNGS) was applied for the identification of H. cinaedi and prolonged minocycline and amoxicillin-clavulanate potassium was used to eradicate the infection. Given the difficulties in culturing this organism, it's highly possible that H cinaedi infections have been overlooked. We suggest that early consideration of H. cinaedi infection should be suspected in immunocompromised patients presenting with unexplained skin lesions as the appropriate antibiotic choice plus a prolonged treatment course is essential for the prognosis. Application of mNGS could contribute to the early identification of rare and cryptogenic pathogens.

Combined Treatment of Progressive Encephalitis in an X-linked Agammaglobulinemia Patient

Most patients with X-linked agammaglobulinemia are susceptible to infections, while some cases also suffer from inflammatory or autoimmune complications. We describe a patient with progressive encephalitis who improved after the use of immunomodulatory treatment with corticosteroids, fluoxetine, and nitazoxanide. In most of the cases the evolution of the progressive encephalitis is complicated and catastrophic. Based on our experience and the review of the literature, we propose the use of this combined treatment to control this devastating complication.

Genetics of Inborn Errors of Immunity in highly consanguineous Middle Eastern and North African populations

Consanguineous marriages in Middle Eastern and North African (MENA) countries are deeply-rooted tradition and highly prevalent resulting into increased prevalence of autosomal recessive diseases including Inborn Errors of Immunity (IEIs). Molecular genetic testing is an important diagnostic tool for IEIs since it provides a definite diagnosis, genotype-phenotype correlation, and guide therapy. In this review, we will discuss the current state and challenges of genomic and variome studies in MENA region populations, as well as the importance of funding advanced genome projects. In addition, we will review the MENA underlying molecular genetic defects of over 2457 patients published with the common IEIs, where autosomal recessive mode of inheritance accounts for 76% of cases with increased prevalence of combined immunodeficiency diseases (50%). The efforts made in the last three decades in terms of international collaboration and of in situ capacity building in MENA region countries led to the discovery of more than 150 novel genes involved in IEIs. Expanding sequencing studies within the MENA will undoubtedly be a unique asset for the IEI genetics which can advance research, and support precise genomic diagnostics and therapeutics.

Human adenoviral (HAdV) chronic arthritis expands the infectious spectrum of primary agammaglobulinemia

Inborn errors of immunity (IEI) are a heterogeneous entity with an increasing number of late diagnoses. Besides infections, inflammatory manifestations are a growing part of the clinical landscape of IEI. These complications are of unknown causes and often lead to the prescription of immunosuppressive agents that worsen the underlying immune defect. We here report the case of an adult patient diagnosed with chronic Human Adenovirus C-1 arthritis in the setting of primary agammaglobulinemia. Metagenomic next-generation sequencing led to the correct diagnosis and high-dose intravenous immunoglobulins resulted in complete recovery. This observation gives new insights into adenoviral immunity and underlines the importance of metagenomics in the diagnosis of inflammatory manifestations in immunocompromised patients.

Are we forgetting to carry out serum protein electrophoresis as part of diagnosis workup?

Background

Common variable immunodeficiency (CVID) is a rare disease that affects children and adults and is often difficult to diagnose. Despite being one of the most frequent causes of immunodeficiency, involving gastrointestinal (GI), respiratory, and hematological systems, the disease onset can have heterogeneous and intermittent symptoms, frequently leading to diagnostic delay. GI symptoms are common and can include diarrhea, but the asymptomatic periods lead to overlooking the recurrent pattern. The same can occur with respiratory infections, thus delaying CVID suspicion. The starting point for CVID diagnosis is the decreased gamma globulin levels in serum protein electrophoresis (SPE), also observed through direct immunoglobulin’s dosage.

Case presentation

The patient is a 38 years-old man who had intermittent diarrhea and recurrent airway infections for 19 years, but the CVID diagnosis was achieved only after SPE was carried out. At that time, he was already malnourished, and developed other complications related to CVID in a short period.

Conclusions

SPE is readily available and inexpensive, but is not part of the laboratory approach in diarrhea. According to the case presented herein, it can be useful for patients with recurrent infections or other clues of the disease.

Campylobacter jejuni Pericarditis: A Case Report

Campylobacter jejuni is one of the most common causes of enteritis. In rare cases, extraintestinal infection can occur, with a handful of cases of cardiac involvement, of which the pathophysiological mechanism is unclear. We report a case of pericarditis in a patient with X-linked agammaglobulinemia presenting with chronic diarrhea and chest pain who evolved to cardiac tamponade, requiring a pericardial window and a long course of broad-spectrum antibiotics. To the best of our knowledge, this is the third case of pericarditis caused by Campylobacter jejuni reported in the literature, the second in a patient with X-linked agammaglobulinemia. Despite its rarity, this case serves as a reminder of Campylobacter as a potential cause of cardiac inflammation for clinicians treating pericarditis/myocarditis, especially in patients with a history of diarrhea or immunosuppression.

Clinical and Genetic Spectrum of Inborn Errors of Immunity in a Tertiary Care Center in Southern India

OBJECTIVES

To study the incidence, clinical manifestations, and genetic spectrum of primary immunodeficiency diseases (PID)/inborn errors of immunity (IEI) in a tertiary care hospital in Southern India.

METHODS

A retrospective analysis of all patients with a clinical suspicion of PID/IEI seen at a tertiary care hospital was performed. All patients had at least one or more warning signs of PID. Serum immunoglobulin levels and other targeted investigations were performed as warranted by the clinical presentation. All families with suspected PID were counseled and offered genetic testing.

RESULTS

A total of 225 children were evaluated for PID during the study period of 6 y. Fifty-six of them did not meet the European Society of Immunodeficiencies (ESID) criteria (working definition of clinical diagnosis) and were excluded. An IEI was found in 30/49 (61.2%) patients. The most frequent reason for referral was recurrent/unusual or serious infections (28%), or cytopenia (16%). Group IV diseases of immune dysregulation was the most common category (19%), followed by group III predominant antibody deficiencies in 23/163 (14%), as per the International Union of Immunological Societies (IUIS) classification.

CONCLUSIONS

This study highlights the heterogeneity of the present cohort, the underuse of genetic tests, and efforts to provide optimal care for children with possible IEI in this center.

B cell repertoire in patients with a novel BTK mutation: expanding the spectrum of atypical X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) is caused by mutations in the Bruton tyrosine kinase) BTK) gene. Affected patients have severely reduced amounts of circulating B cells. Patients with atypical XLA may have residual circulating B cells, and there are few studies exploring these cells' repertoire. We aimed to study the B cell repertoire of a novel hypomorphic mutation in the BTK gene, using the next generation sequencing (NGS) technology. Clinical data was collected from our clinical records. Real-time PCR was used to determine KREC copies, and NGS was used to determine the immunoglobulin (Ig) heavy chain (IgH) repertoire diversity. Both patients had a relatively mild clinical and laboratory phenotype, residual BTK protein expression, and the same novel mutation in the BTK gene, c.1841 T > C, p. L614P. Signal-joint kappa-deleting recombination excision circles (sj-KREC) for both patients were completely absent reflecting lack of naïve B cells. The intron RSS-Kde coding joints (cj) were significantly reduced, reflecting residual replicating B cells. NGS displayed restricted IgH repertoire with highly uneven distribution of clones, especially for Pt2. We report a novel BTK mutation, c.1841 T > C (p. L614P) that is associated with a relatively mild phenotype. We conclude that the IgH repertoire in atypical XLA is restricted with highly uneven distribution of clones. This phenomenon may be explained by extremely reduced to non-existent levels of BTK in B cells. This report sheds further light on atypical cases of XLA.

Agammaglobulinemia: from X-linked to Autosomal Forms of Disease

Interruptions or alterations in the B cell development pathway can lead to primary B cell immunodeficiency with resultant absence or diminished immunoglobulin production. While the most common cause of congenital agammaglobulinemia is X-linked agammaglobulinemia (XLA), accounting for approximately 85% of cases, other genetic forms of agammaglobulinemia have been identified. Early recognition and diagnosis of these conditions are pivotal for improved outcomes and prevention of sequelae and complications. The diagnosis of XLA is often delayed, and can be missed if patient has a mild phenotype. The lack of correlation between phenotype and genotype in this condition makes management and predicting outcomes quite difficult. In contrast, while less common, autosomal recessive forms of agammaglobulinemia present at younger ages and with typically more severe clinical features resulting in an earlier diagnosis. Some diagnostic innovations, such as KREC level measurements and serum BCMA measurements, may aid in facilitating an earlier identification of agammaglobulinemia leading to prompt treatment. Earlier diagnosis may improve the overall health of patients with XLA.

Disseminated Intravascular Coagulation Associated with Large Deletion of Immunoglobulin Heavy Chain

Although the majority of monogenic defects underlying primary immunodeficiency are microlesions, large lesions like large deletions are rare and constitute less than 10% of these patients. The immunoglobulin heavy chain (IGH) locus is one of the common regions for such genetic alterations. This study describes a rare case of autosomal recessive agammaglobulinemia with a homozygous large deletion in chromosome 14q32.33 (106067756-106237742) immunoglobulin heavy chain clusters with an unusual and severe skin infection and disseminated intravascular coagulopathy.

Compassionate use of REGN-COV2 in the treatment of COVID-19 in a patient with impaired humoral immunity

Background

The role of antibodies in coronavirus disease 2019 (COVID-19) in patients with X-linked agammaglobulinaemia (XLA) has yet to be characterised and clinical courses observed in this cohort of patients have been heterogeneous. Whilst some exhibit spontaneous recovery, others have experienced a more protracted disease length. Previous reports have described successful use of convalescent plasma, however there is a paucity of information around the use of the REGN-COV2 antibody cocktail in these patients.

Case report

A patient with XLA was admitted to hospital with COVID-19 and remained persistently symptomatic with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) swab positivity despite treatment with Remdesivir and dexamethasone. Attempts at modulating the immune response with anakinra were unsuccessful. Consent for compassionate use of REGN-COV2 was obtained with administration taking place on day 87 of his illness. This was followed by a period of convalescence and SARS-CoV-2 nasopharyngeal swab negativity. As a consequence of prolonged immunosuppression, the patient developed pneumocystis pneumonia.

Conclusion

This case highlights the role of antibodies in clearing SARS-CoV-2 in a hypogammaglobulinaemic host and demonstrates the consequences of prolonged immunosuppression and delayed treatment. We propose that this may be of particular significance given the capacity of SARS-CoV-2 to develop advantageous mutations in a chronically infected host.

Human Inborn Errors of Immunity (HIEI): predominantly antibody deficiencies (PADs): if you suspect it, you can detect it

OBJECTIVE

This minireview gathers the scientific foundations of the literature on genetic errors in the development of the humoral immune system to help pediatricians suspect these defects.

SOURCES

A systemic search using the PubMed MEDLINE database was performed for all Predominantly Antibody Deficiencies (PADs) described in the 2020 IUIS Expert Committee for PID classification system, combined with terms for hypogammaglobulinemia. Search terms for PADs were based on the listed names and affected genes as classified by the IUIS 2020. Abstracts of the results were reviewed to find relevant case series, review articles of PADs associated with infection, opportunistic infection, autoimmunity, cytopenias, malignancies, inflammatory diseases, neurological and respiratory diseases. References from relevant articles were further reviewed for additional references. Relevant findings were grouped in accordance with the IUIS 2020 classification system. Clinical and genetic features, if known, were described.

DATA SYNTHESIS

PADs refer to impaired antibody production due to molecular defects intrinsic to B cells or a failure of interaction between B and T cells. The patients develop recurrent or chronic infection or respond to the antigens with dysregulation of the immune function, causing severe allergy, autoimmunity, inflammation, lymphoproliferation and malignancy. The diagnosis is a combined exercise of clinical and laboratory investigation similar to that performed by Bruton (1952). In the context of SARS-CoV-2 infection, the experience of XLA and CVID patients has been surprising. Variants in 39 genes were reported as causing PADs, but the clinical heterogeneity within each variant is not clear.

CONCLUSION

Bruton (1952) used clinical expertise and protein electrophoresis to identify XLA. The IUIS (2020) committee used immunoglobulins and B lymphocyte to characterize PADs. Pediatricians should suspect it to detect it and prevent morbidities that can have an astonishing and irreversible impact on the child's life.

Primary immunodeficiency from B-cell defect: a case series of 6 patients seen in a national tertiary hospital in the Philippines

Primary immunodeficiency disorders, although rare, pose a significant burden in the quality of life of afflicted patients and their families. The most common of these disorders are caused by B-cell defects. A total of 6 patients were seen and diagnosed in a national tertiary hospital in the Philippines from 1996 to 2018. These patients were admitted due to various infections, and were subsequently diagnosed to have B-cell defects. Four out of the 6 patients have genetic studies confirming the diagnosis of X-linked agammaglobulinemia. One patient succumbed to sepsis at 10 years of age, while the rest are on follow-up at the Philippine General Hospital for intravenous immunoglobulin infusion.

COVID-19 neutralizing antibody-based therapies in humoral immune deficiencies: A narrative review

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS−COV-2), generated an unprecedented global health and social emergency. Despite many efforts from clinicians to develop effective anti−COVID-19 treatment protocols, no specific therapy is currently available. Among anti-viral agents, convalescent plasma (CP) from recovered patients is the object of intense research following the first positive reports in severe COVID-19 patients. Passive immunotherapy the rationale to provide higher benefits in COVID-19 patients with humoral immune deficiencies, such as those with solid and hematologic cancers, patients with primary and acquired immunodeficiencies, and recipients of solid organ and hematopoietic stem cell transplants. The aim of this narrative review will be to critically discuss the literature evidence on CP use in these categories of patients.

Novel deletion mutation in Bruton’s tyrosine kinase results in X-linked agammaglobulinemia: A case report

BACKGROUND

X-linked agammaglobulinemia is a primary immunodeficiency disease caused by gene mutations of Bruton’s tyrosine kinase (BTK). We found a new mutation point and summarized the correlation analysis and performed a literature review.

CASE SUMMARY

The proband was a 5-year-old boy. He was admitted to our hospital due to a recurrent cough and a fever that had persisted for a month. He had a history of multiple respiratory infections and sinusitis. There was no immunodeficiency or recurrent infection history among his family members. Agammaglobulinemia was characterized as follows: Immunoglobulin (Ig) A, 90.0 mg/dL (90-450 mg/dL); IgG, 20.0 mg/dL (800-1800 mg/dL); and IgM, 18.0 mg/dL (60-280 mg/dL). Notably, the assessment of IgG subtypes revealed the following very low levels: Subtype 1, 0.26 g/L (3.62-12.28 g/L); subtype 2, 0.10 g/L (0.57-2.9 g/L); subtype 3, 0.009 g/L (0.129-0.789 g/L); and subtype 4, 0.003 g/L (0.013-1.446 g/L). Cellular immunological test results were as follows: CD3, 74.6% (50%-84.0%); CD4, 47.3% (27.0%-51.0%); and CD8, 24.9% (15.0%-44.0%). A de novo hemizygous deletion in BTK was detected: c.902_c.904delAAG/p.E301del. Transcript levels of the mutant BTK were similar to those of the wild-type gene, though overexpression resulted in markedly reduced levels of mutant BTK (9.49% ± 1.58%), relative to the wild-type BTK (75.8% ± 2.98%, P < 0.01).

CONCLUSION

This case of X-linked agammaglobulinemia was attributed to a de novo hemizygous deletion mutation in BTK (c.902_c.904delAAG/p.E301del). The mutation resulted in markedly reduced BTK protein stability in vitro.

Presentation of a case of Bruton type primary agammaglobulinemia in Guinea

X-linked agammaglobulinemia (XLA) is a rare genetic disease caused by a mutation in the Bruton tyrosine kinase (BTK) gene. It is characterized by a profound deficiency of B cells and a decrease in all classes of immunoglobulins (Ig). We report one case in a 3-year-old boy seen for recurrent acute otitis media, perineal abscess, oligoarthritis. The serum immunoglobulin (Ig) assay showed an IgG level of 0.6g/l. IgM and IgA are indosable. Marrow immunophenotyping showed an absence of precursor B less than 1%. Molecular biology confirmed Burton's disease (stop mutation, C37C) in exon 2 of the BTK gene. Treatment with intravenous immunoglogulin was started.

B Cell Disorders in Children-Part I

PURPOSE OF REVIEW

The advent of enhanced genetic testing has allowed for the discovery of gene defects underlying two broad categories of antibody deficiency in children: agammaglobulinemia and common variable immunodeficiency (CVID). This review describes the underlying gene defects and the clinical manifestations.

RECENT FINDINGS

Because novel monogenetic defects have been discovered in both categories, a strict dichotomous classification of B cell disorders as either X-linked agammaglobulinemia or common variable immunodeficiency is no longer appropriate. Advances in genetic testing technology and the decreasing cost of such testing permit more precise diagnosis of B cell disorders, more helpful information for genetic counselors, and a better understanding of the complex process of B cell development and function. More disorders await discovery.

Flow-cytometry as an auxiliary in the diagnosis of primary humoral immunodeficiencies

Background

Antibody deficiencies encompass a wide spectrum of pathologies and constitute approximately 50 % of primary immunodeficiencies; with cytometry, it is possible to evaluate the immune status rapidly, effectively and at low cost.

Objective

To assess, by means of flow cytometry, the cells of patients with three types of primary humoral immunodeficiencies.

Method

Using flow cytometry, blood samples from patients and healthy subjects were analyzed with different monoclonal antibodies.

Results

Using various stains, a severe decrease in B lymphocytes was shown in patients with X-linked agammaglobulinemia, as well as a lack of CD154 expression in patients with hyper-immunoglobulin M syndrome, and heterogeneity of B lymphocyte subpopulations in patients with common variable immunodeficiency.

Conclusion

Flow cytometry enables early diagnosis of primary immunodeficiencies with a high level of confidence and, in many cases, identification of the genes involved.

Chronic high-level multidrug-resistant Campylobacter coli enterocolitis in an agammaglobulinemia patient: Oral gentamicin efficacy

BACKGROUND

Campylobacter is the most common cause of infectious diarrhea in agammaglobulinemia patients. These infections can be severe, prolonged, and recurrent in such patients.

PATIENT AND METHODS

We report a 29-year-old male patient with X-linked agammaglobulinemia with Campylobacter coli enterocolitis that persisted for nine months despite multiple 10- to 14-day courses of oral ciprofloxacin and azithromycin.

RESULTS

The isolate was highly resistant to ciprofloxacin, erythromycin, tetracycline, and fosfomycin. The patient failed to respond to intravenous ertapenem, 1.0g/day for two weeks, to which the pathogen was susceptible. He was finally cured with oral gentamicin, 80mg four times daily, and stool cultures remained negative during the seven-month follow-up.

CONCLUSION

Oral aminoglycoside might be the most appropriate choice for eradication of persistent Campylobacter in the intestinal tract for macrolide- and fluoroquinolone-resistant isolate in agammaglobulinemia patients with chronic diarrhea or relapsing systemic infections.

Plasma therapy leads to an increase in functional IgA and IgM concentration in the blood and saliva of a patient with X-linked agammaglobulinemia

BACKGROUND

Patients with X-linked agammaglobulinemia (XLA) are protected against invasive bacterial infections due to IgG replacement therapy, but are still at higher risk for mucosal infections of the gut and respiratory tract. This might be explained by to the lack of IgA and IgM, as these antibodies are especially important for protection against invading bacterial pathogens on the mucosal surface.

METHODS

In an attempt to eliminate a chronic norovirus infection in a patient with X-linked agammaglobulinemia, fresh frozen plasma (FFP) was given two times a week for 3 weeks. At each visit, pre- and post-FFP infusion serum and saliva was collected to determine IgG-, IgA- and IgM-concentrations and serum half-life was calculated. Functionality of the immunoglobulins pre- and post-FFP infusion in both serum and saliva was tested by measuring complement activation, agglutination and killing of non-typeable Haemophilus influenzae (NTHi).

RESULTS

Administration of FFP failed to eradicate the chronic norovirus infection. Serum IgA and IgM half-life was 4.2 ± 0.3 and 3.8 ± 0.3 days, respectively. The presence of serum IgM was associated with increased complement binding and complement-mediated killing of NTHi. IgA in saliva was detectable post-FFP and was associated with increased agglutination of NTHi. IgM in saliva was not detectable.

CONCLUSIONS

We conclude that FFP treatment, although ineffective in clearing a chronic norovirus infection in this single patient, might be beneficial to prevent or eliminate bacterial infections in XLA patients by increasing IgM dependent complement-mediated killing in serum and IgA dependent bacterial agglutination on the mucosal surface.

X-linked agammaglobulinemia (XLA):Phenotype, diagnosis, and therapeutic challenges around the world

Background

X-linked agammaglobulinemia is an inherited immunodeficiency recognized since 1952. In spite of seven decades of experience, there is still a limited understanding of regional differences in presentation and complications. This study was designed by the Primary Immunodeficiencies Committee of the World Allergy Organization to better understand regional needs, challenges and unique patient features.

Methods

A survey instrument was designed by the Primary Immunodeficiencies Committee of the World Allergy Organization to collect both structured and semi-structured data on X-linked agammaglobulinemia. The survey was sent to 54 centers around the world chosen on the basis of World Allergy Organization participation and/or registration in the European Society for Immunodeficiencies. There were 40 centers that responded, comprising 32 countries.

Results

This study reports on 783 patients from 40 centers around the world. Problems with diagnosis are highlighted by the reported delays in diagnosis>24 months in 34% of patients and the lack of genetic studies in 39% of centers Two infections exhibited regional variation. Vaccine-associated paralytic poliomyelitis was seen only in countries with live polio vaccination and two centers reported mycobacteria. High rates of morbidity were reported. Acute and chronic lung diseases accounted for 41% of the deaths. Unusual complications such as inflammatory bowel disease and large granular lymphocyte disease, among others were specifically enumerated, and while individually uncommon, they were collectively seen in 20.3% of patients. These data suggest that a broad range of both inflammatory, infectious, and autoimmune conditions can occur in patients. The breadth of complications and lack of data on management subsequently appeared as a significant challenge reported by centers. Survival above 20 years of age was lowest in Africa (22%) and reached above 70% in Australia, Europe and the Americas. Centers were asked to report their challenges and responses (n = 116) emphasized the difficulties in access to immunoglobulin products (16%) and reflected the ongoing need for education of both patients and referring physicians.

Conclusions

This is the largest study of patients with X-linked agammaglobulinemia and emphasizes the continued morbidity and mortality of XLA despite progress in diagnosis and treatment. It presents a world view of the successes and challenges for patients and physicians alike. A pivotal finding is the need for education of physicians regarding typical symptoms suggesting a possible diagnosis of X-linked agammaglobulinemia and sharing of best practices for the less common complications.

Severe combined immunodeficiency (SCID) presenting in childhood, with agammaglobulinemia, associated with novel compound heterozygous mutations in DCLRE1C

Severe combined immunodeficiency (SCID) can be caused by deleterious mutations in DCLRE1C, leading to deficient non-homologous end joining by compromising the function of the Artemis protein. This impairs the process of V(D)J recombination of the T- and B-cell receptors and typically results in radiosensitive T^-, B^-, NK⁺ SCID presenting during the first months of life. We present a case of a 3-year-old girl with two novel compound heterozygous variants in DCLRE1C (c.58G>C and c.374A>C) that were associated with marked reduced numbers of peripheral T- and B-cells and undetectable total serum IgG. Despite the severe laboratory phenotype, the patient had a normal development, albeit failure to thrive (-2.5 to -3 SD), during her first years of life including day-care attendance at preschool for 1.5 years. After being diagnosed with pneumonia the clinical picture of SCID was recognized and the girl successfully underwent hematopoietic stem-cell transplantation.

Primary B-cell immunodeficiencies

Primary B-cell immunodeficiencies refer to diseases resulting from impaired antibody production due to either molecular defects intrinsic to B-cells or a failure of interaction between B-cells and T-cells. Patients typically have recurrent infections and can vary with presentation and complications depending upon where the defect has occurred in B-cell development or the degree of functional impairment. In this review, we describe B-cell specific immune defects categorized by presence or absence of peripheral B-cells, immunoglobulins isotypes and evidence of antibody impairment.

Timing of infections in patients with primary immunodeficiencies treated with intravenous immunoglobulin (IVIg)

Purpose

Patients with common variable immune deficiency and X-linked agammaglobulinemia are unable to produce their own antibodies thus leading to a higher incidence of recurrent infections, particularly those involving the sinuses and lungs. Treatment with intravenous immunoglobulin therapy aims to reduce the incidence of infections; however, as serum IgG approaches its trough during the third and fourth week after infusion, we hypothesized that the rate of infection would be higher during this time period.

Methods

Patients with a diagnosis of either common variable immunodeficiency (CVID) or X-linked agammaglobulinemia (XLA) treated with intravenous immunoglobulin (IVIg) were analyzed in a prospective cohort study. Data was obtained as to the timing of symptom onset post infusion, the type of infection, as well as timing of the initiation of antibiotics. Descriptive analyses were conducted to explore the patterns of the data at each month and then over the course of the study year.

Results

Twenty-three patients with a diagnosis of either CVID (n = 22), or XLA (n = 1) were enrolled with a mean follow duration of 11.3 months. The mean number of days to infection after IVIg infusion, the primary endpoint, was 17.0 days with the most common infections reported as sinusitis and upper respiratory tract infections. There was no statistically significant difference (p = 0.70) in the rates of infection when considering the weeks post-infusion.

Conclusions

We believe that this pilot study is the first reported prospective study to examine the timing of infections after IVIg infusion in individuals with CVID and XLA. Further multi-centered research with a larger sample size is required into the comparison of infection rates in primary immunodeficiency patients treated with IVIg versus subcutaneous immunoglobulin therapy, where serum IgG levels remain at steady state.

Autosomal Recessive Agammaglobulinemia Due to a Homozygous Mutation in PIK3R1

The role of class IA phosphoinositide 3 kinases (PI3Ks) in immune function and regulation continues to expand with the identification of greater numbers of genetic variants. This case report is the second reported case of a homozygous premature stop codon within the PIK3R1 gene leading to autosomal recessive agammaglobulinemia. The proband, born to consanguineous parents, presented at 10 months of age with a history of oropharyngeal petechiae and bleeding from the mouth, gums, and tear ducts. Initial investigations revealed thrombocytopenia, neutropenia and the absence of B cells. Further genetic testing via a custom next-generation sequencing panel confirmed the presence of a homozygous mutation in PIK3R1, c.901 C>T, a premature stop codon at amino acid position 301. Given their many roles in immune regulation, recessive mutations in the PlK3R1 gene should be considered in infants presenting with hypogammaglobulinemia or agammaglobulinemia, particularly in the setting of parental consanguinity.

Pyoderma Gangrenosum in a Patient with X-Linked Agammaglobulinemia

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder caused by germline mutations of B-cell tyrosine kinase (BTK) gene. It is characterized by decreased serum immunoglobulins levels and circulating mature B cells. This defect in humoral immunity leads to increased susceptibility to infection. Pyoderma gangrenosum (PG) is an uncommon, ulcerating, neutrophilic dermatosis. Here we report PG in an 8-year-old patient with XLA. The patient received intravenous immunoglobulin treatment in conjunction with prednisone and topical application of 0.03% tacrolimus ointment and the ulcer was almost completely healed in the 2 weeks of follow-up. The coexistence has been rarely reported. XLA may be a possible cofactor in the pathogenesis of PG.

Terminal 14q32.33 deletion as a novel cause of agammaglobulinemia

Over the past decades, a pleiotropic spectrum of B-cell intrinsic defects leading to early onset agammaglobulinemia and absent B cells has been described. Herein we report terminal 14q32.33 deletion as a novel cause of agammaglobulinemia. We describe a 20-year old man with a 1MB terminal 14q32.33 deletion resulting in a loss of the entire Immunoglobulin heavy chain gene region of chromosome 14. The patient presented with absent serum immunoglobulin levels and absent circulating B cells since age 2. The clinical picture was dominated by severe episodes of recurrent upper respiratory tract infections. In the literature, the most prevalent features of terminal 14q32.33 deletions include mental disability, facial malformation, hypotonia, seizures, and visual problems with retinal abnormalities. Neither increased susceptibility to infections nor agammaglobulinemia have been described as a manifestation of terminal 14q32.33 deletion. Thus, our findings expand the known clinical spectrum of terminal 14q32.33 deletion to include susceptibility to infections.

[Two families of X-linked lymphoproliferative disease type 1 characterized by agammaglobulinemia]

Objective: To investigate the clinical and immunological laboratory features, mutations in SH2D1A gene and SAP protein expression in four children of two families with X-linked lymphoproliferative disease type 1(XLP-1). Method: Four patients (Family A including Patient 1 and Patient 2, Family B including Patient 3 and Patient 4) and their maternal relatives were enrolled in this study. The clinical manifestation, EBV infection status and chest CT scan were analyzed. The absolute and relative numbers of lymphocyte subsets, T lymphocyte proliferative response, SAP protein expression were assessed by flow cytometry. Quantification of signal joint TCR rearrangementexcision circle (sjTRECs), CDR3 spectratyping of TCRvβ and gene mutation of SH2D1A were detected by PCR based on genomic DNA or cDNA. Result: Four male patients from two families were diagnosed with XLP-1. The ages of disease onset were more than 1 year, more than 1 year, more than 1 month and 6 months. The ages at diagnosis were nine years and ten months, sixteen years and eight months, fourteen years and ten months, four years and nine months. All patients had recurrent infections and EBV infection. Patients 1, 2, and 3 had agammaglobulinemia and Patient 4 had hypogammaglobulinemia. Chest CT scan showed all patients had atelectasis and pneumonia, and Patient 3 had bronchiectasis. Patient 3 was diagnosised as Burkitt lymphoma. For immunological function, all patients exhibited reduced CD4/CD8 ratios, increased numbers of exhausted T lymphocyte, decreased number of NK cell. The numbers of total B lymphocyte and naïve B lymphocyte were normal, but the number of memory B lymphocyte declined in all cases. Four patients' copy numbers of sjTRECs were low and CDR3 spectratypings of TCRvβ showed mildly skewed. But their T lymphocyte proliferative response was normal. SAP protein expression in four cases were measured by flow cytometry. Two patients from Family A were absent and two patients from Family B showed decreased values. SH2D1A gene sequence analysis showed that the patients of Family A harbored a nonsense mutation (c.163 C>T; p.R55X) in exon 2. Their mother and two sisters were carriers. A missense mutation of SH2D1A gene (c.278 G>A; p.G93D) in exon 3 was found in the patients of Family B. The mother was carrier. Four patients remain survived, Patient 3 gave up treatment, other three patients received IVIG therapy. Conclusion: Four patients with XLP-1 from two families characterized by agammaglobulinemia have an extreme vulnerability to Epstein-Barr virus (EBV) infection. The functions of T cell, B cell and NK cell are impaired at different stages. The detection of SAP protein and SH2D1A gene are the key methods for diagnosis of XLP-1.

Thymoma-associated immunodeficiency: a diagnostic challenge for the clinician

Good's syndrome or thymoma-associated immunodeficiency is a rare clinical entity that is often presumed to be common variable immunodeficiency, due to lack of awareness and recognition of this syndrome. This syndrome more often goes unrecognized if a thymoma is not detected. An appropriate immunological work-up that aids timely diagnosis and adequate therapy with antimicrobials and intravenous immunoglobulins are mandatory to prevent the long-term complications and mortality associated with this syndrome. We present the clinical and immunological profile of a young man with Good's syndrome that was initially presumed to be common variable immunodeficiency.

A Rare Case of Strongyloides Hyperinfection from Hypogammaglobulinemia

Strongyloides infection can range from asymptomatic eosinophilia to disseminated disease. Common in tropical and subtropical nations, it can lead to hyperinfection, an autoinfection increasing parasitic burden in immunocompromised. Cell-mediated immunity is important in combating parasite infection. We present a case of Strongyloides hyperinfection in hypogammaglobulinemia which was refractory to conventional treatment but responded to immunoglobulin administration with complete resolution indicating role of humoral immunity also.

[Type and location of bronchiectasis in a cohort of adults with common variable immunodeficiency]

BACKGROUND

Bronchiectasis are permanent dilatations of the bronchi. Its prevalence in patients with variable common immunodeficiency (CVID) is high, however there is little information regarding the type and location of the same; therefore the objective of this study is to know the type and location of bronchiectasis in a cohort of adult patients with CVID.

METHODS

It has been made a transversal, observational and descriptive study that included 32 adult patients with diagnosis of CVID according to the criteria of the European Society of Immunodeficiencies (ESID). All patients underwent high resolution pulmonary computed tomography (HRCT), which were interpreted by an expert radiologist. The frequency, type and location of bronchiectasis were reported using descriptive statistics.

RESULTS

Thirty-two adult patients, ten men (31.25%) and 22 women (68.7%), were included. 40.6% had bronchiectasis. 23% had a lobe involvement, 15.3% two lobes, 46.1% 3 lobes and 15.3% complete involvement of the parenchyma. The types of bronchiectasis were distributed as follows: tubular 38.4%, varicose 23% and cystic and tubular combinations 15.3%, cystic and varicose 15.3% and cystic, tubular and varicose 7.6%.

CONCLUSIONS

Our results show that 40% of adult patients with CVID have BQs, usually affecting three pulmonary lobes, located mainly in the right and middle lower lobe; The tubular type, is the most common. Their timely diagnosis and treatment can improve survival and reduce costs for patients and health care.

Two young stroke patients associated with regular intravenous immunoglobulin (IVIg) therapy

We recently experienced 2 young adult patients who developed ischemic stroke after regular intravenous immunoglobulin (IVIg) therapy for agammaglobulinemia with diagnosis of common variable immunodeficiency (CVID) in their childhood. Patient 1 was 26-year-old woman, who developed Wallenberg's syndrome 6 days after the last IVIg therapy, but had no further stroke recurrence with cilostazol later. Patient 2 was 37-year-old man, who developed recurrent cerebral infarction in the territory of bilateral lenticulostriate branches like branch atheromatous disease (BAD) several days after the IVIg therapy. However, he had no further stroke recurrence after bone marrow transplantation (BMT) therapy for his lymphoproliferative disorder. It was suggested that IVIg therapy was associated to these different types of ischemic stroke in our 2 young adult patients with minimal vascular risk factors. Although IVIg therapy is widely used as a relatively safe medication for immunodeficiency disorders or autoimmune diseases, we need to pay more attention to stroke occurrence with regular IVIg therapy.

[X-linked agammaglobulinemia: experience in a Portuguese hospital]

INTRODUCTION

X-Linked agammaglobulinemia (XLA) is characterized by an arrest of B cell differentiation, leading to recurrent bacterial infections. Lifelong immunoglobulin replacement therapy (IRT) is indicated to prevent infections and their complications.

MATERIAL AND METHODS

A retrospective study of patients with XLA followed in a level three hospital was performed; data was collected retrospectively by review of clinical files.

RESULTS

XLA was diagnosed in 9 children. One (11%) had a positive family history with a prenatal diagnosis. Infection was the clinical presentation in all the others (89%), at an average age of 13 months; diagnosis was established at a mean age of 3.4 years. Acute otitis media (7/9) and pneumonia (5/9) were the most frequently observed. Seven (78%) presented serum immunoglobulin G (IgG) levels below 200mg/dL and all of them had CD19(+) B cells below 2%. Neutropenia was present at diagnosis in three patients (33%). Bruton tyrosine kinase (BTK) mutations were identified in all cases. Intravenous IRT was initiated, switched later to subcutaneous administration, in all. The mean time of follow-up was 10.7 years with cumulative time of 97 years. Eight children (89%) achieved IgG serum levels above 800 mg/dL. One presented lower values due to renal loss. No deaths occurred. After diagnosis the most frequent infections were acute otitis media (6/9). In spite of stable adequate IgG levels on IRT, two patients developed bronchiectasis.

CONCLUSIONS

XLA overall prognosis is good, as long as patients have an early and adequate treatment. However, bronchiectasis can occur even on adequate immunoglobulin replacement therapy.

[Humoral immunodeficiency : awareness for better support]

Les déficits immunitaires humoraux (DIH) sont des maladies hétérogènes allant des formes asymptomatiques rencontrés lors des déficits sélectifs en immunoglobulines A (IgA) et en sous-classes d'IgG aux formes graves des agammaglobulinémies congénitales. Les patients atteints de DIH présentent souvent des infections ORL ou des voies respiratoires récidivantes ou sévères. Ces patients peuvent présenter un certain nombre de complications non infectieuses, telles que des manifestations auto-immunes et des entéropathies, qui pourraient être le seul symptôme clinique révélateur. Les formes sévères des DIH sont facilement diagnostiquées grâce au dosage des IgG totaux, des IgA et des IgM. La thérapie substitutive par les immunoglobulines reste le traitement de choix chez ces patients.

Intravenous immunoglobulin in pediatrics: A review

There has been a rapid expansion of the use of intravenous immunoglobulin (IVIG) for an ever-growing number of conditions. IVIG is used at a 'replacement dose' (400-600 mg/kg/month) in antibody deficiencies and is used at a high dose (2 g/kg) as an 'immunomodulatory' agent in an increasing number of immune and inflammatory disorders.(1) The limitations for IVIG are the cost of the preparation and the need for intravenous infusions. Due to the cost, shortages and growing use of IVIG there have been attempts to develop evidence-based guidelines for the use of IVIG in a wide variety of immune disorders in children and neonates. This commentary provides the recommendations and recent publication regarding the use of IVIG in various conditions in children.

A case of Fabry's disease with congenital agammaglobulinemia

Fabry's disease is an X-linked lysosomal storage disorder caused by abnormalities in the α-galactosidase A (GLA) gene, which leads to a GLA deficiency and to the intracellular deposition of globotriaosylceramide (Gb3) within vascular endothelium and other tissues. It manifests as progressive multiple organ dysfunctions caused by the deposition of Gb3. On the other hand, congenital agammaglobulinemia is usually caused by mutations in Bruton's tyrosine kinase (Btk) gene with X-linked dominence, suppresses B cell maturation, and causes recurrent pyogenic infections. In former reports, the distance between the loci in the Xq22 region of the human X chromosome was found to be about 69 kilobases. A 23-yr-old man diagnosed with congenital agammaglobulinemia at age 5, showed typical clinical and laboratory and histopathological findings of Fabry's disease. The genetic basis of this combination of the two syndromes was studied in this patient. Here, we report a case of Fabry's disease with congenital agammaglobulinemia.