Wiskott-Aldrich syndrome: diagnosis, current management, and emerging treatments

An Introduction to the Complete Blood Count for Clinical Chemists: White Blood Cells

BACKGROUND

The most frequently ordered laboratory test worldwide is the complete blood count (CBC). As clinical chemists are increasingly assigned to assist or direct laboratories outside of the traditional clinical chemistry sections, such as the automated hematology section, expertise must be established. This review article is a dedication to that ongoing effort.

CONTENT

In this primer, the white blood cell (WBC) test components of the CBC are introduced, followed by a discussion of the laboratory evaluation of leukopenia and leukocytosis.

SUMMARY

The laboratorian's approach to consult cases should be guided by the patient's clinical history and presentation while being able to provide key laboratory-based insights to assist in resolving result discrepancies that may otherwise go unnoticed.

Mutational Landscape of Patients with Wiskott Aldrich Syndrome: Update from India

PURPOSE

Wiskott-Aldrich syndrome (WAS) is an X-linked genetic disorder characterized by distinctive features including microthrombocytopenia, eczema and recurrent infections. In the present study we report clinical, immunological and molecular spectrum of 41 WAS patients diagnosed over last five years.

METHODS

Clinical and family history was collected from case records. Comprehensive immunological assessments including lymphocyte subset analysis, and flow cytometry based evaluation of WAS protein (WASP) expressions were performed in patients along with evaluation of carrier status in mothers. Genetic analysis was carried out with either Sanger sequencing or targeted exome sequencing.

RESULTS

The patients included in this study presented at a median age of 9.5 months, with two adult cases. Clinical manifestations encompassed thrombocytopenia, eczema, bleeding, diarrhea, respiratory tract infections, CMV infection, and malignancy. Immunological phenotype revealed T cell lymphopenia, B cell lymphopenia, and elevated IgE levels. Flow cytometry analysis of WASP was performed in 36 cases out of which 68.42% demonstrated complete absent expression while others showed reduced expression. Genetic analysis highlighted that the majority of mutations affect the WH1 domain of WASP while both adult patients showed intronic mutations. Molecular Dynamics analysis conducted for the novel variants P398R and G33R showed an average RMSD (Å) higher than that of the wild type, indicating greater structural perturbations in WASP.

CONCLUSION

In the present study we have documented 56.09% novel WAS mutations in Indian cohort. Notably, the application of flow cytometry has emerged as a valuable and efficient diagnostic tool for identifying these WAS patients.

Risk factors and disease trajectories of recurrent immune thrombocytopenia in children

This retrospective study aimed to analyse the course and outcome of recurrent immune thrombocytopenia (ITP) in children and to identify factors associated with recurrence. A total of 497 newly diagnosed ITP children with platelet <30 × 109/L between January 1988 and December 2019 were included. Recurrent ITP was defined as a new event of thrombocytopenia after at least 3 months of remission without treatment. Twenty-nine (5.8%) children experienced 48 recurrent episodes. The median time from diagnosis to recurrence was 22 months. Most recurrences occurred in children aged 1.5-10 years with a recent infection history. Compared to non-recurrent ITP, children with recurrent ITP had delayed remission with lower platelets at 1 month and 3 months postdiagnosis. Multivariate analysis identified aged 1.5-10 years (hazard ratio [HR] 3.65, 95% confidence interval [CI]: 1.35-9.82) and delayed remission at 7-12 months (HR 4.04, 95% CI: 1.37-11.95) as predictors for recurrence. Most recurrent ITP patients had minor or mild symptoms, higher platelet counts, did not require treatment, and achieved remission within 12 months. The similar remission trajectories among the first and recurrent ITP, but different from the courses in the non-recurrent ITP, suggest that recurrent ITP might have a unique biological basis.

[Differential diagnosis and therapy of immune thrombocytopenia]

Immune thrombocytopenia is caused by autoantibodies against surface antigens on platelets. Since only about 50 % of cases will allow the identification of glycoprotein-specific antibodies, ITP remains a diagnosis of exclusion. Apart from EDTA-induced pseudo thrombocytopenia, other diseases like secondary thrombocytopenia due to medication, a large number of other disease and hereditary thrombocytopenias must be taken into account. The first-line therapy of ITP includes corticosteroids and intravenous immunoglobulins. The second line consists of thrombopoietin receptor agonists, rituximab, or splenectomy. For further lines of therapy, Fostamatinib and non-steroidal immunosuppressives are available.

Wiskott-Aldrich Syndrome: A Report of a Rare X-Linked Disorder

Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive genetic disorder marked by eczema, thrombocytopenia, and immunodeficiency. The associated immune dysregulation increases the risk of autoimmune disorders and lymphoid malignancies. WAS results from mutations in the WAS protein gene on the short arm of the X chromosome. Here, we present the case of a seven-month-old male, born to non-consanguineous parents with no significant birth or family history. The child had height, weight, and head circumference below the third percentile for age and presented with recurrent mild upper respiratory infections, mild eczema, and thrombocytopenia. Despite symptomatic treatment and clinical improvement, platelet counts continued to decline. A provisional diagnosis of immune thrombocytopenia was made, and intravenous immunoglobulin was administered, which halted the downward trend but did not improve platelet counts. Autoimmune testing revealed strong positivity for antinuclear antibodies (ANA). Given the early-onset thrombocytopenia, anemia, and failure to thrive, autoimmune lymphoproliferative syndrome was suspected. However, T cell subset analysis was normal. A bone marrow biopsy suggested myelodysplastic syndrome or myeloproliferative neoplasm, but molecular studies were negative. Due to the early-onset autoimmunity and strongly positive ANA, genetic testing via whole exome sequencing confirmed the diagnosis of WAS.

Inborn Errors of Immunity

Inborn errors of immunity occur in 1 in 1000 to 1 in 5000 individuals and are characterized by immune deficiency and immune dysregulation. The primary care provider (PCP) should be familiar with key features of these diagnoses including recurrent and/or severe infections, hyperinflammation, malignancy, and autoimmunity and have a low threshold to refer for evaluation. The PCP can begin a laboratory evaluation before referral by sending a complete blood count (CBC) with differential, antibody levels, vaccine titers, and possibly other tests. Management approaches vary from antibiotic prophylaxis to hematopoietic stem cell transplantation depending on the specific diagnosis.

[Relevant cutaneous manifestations as indications for inborn errors of immunity]

Inborn errors of immunity (IEI) can affect different parts of the immune system and manifest especially through pathological infection susceptibility and immune dysregulation. Cutaneous manifestations of IEI can hint at the underlying immunodeficiency and the tendency for infection and inflammation. These manifestations can present as recurring eczema, erythema, abscesses, and hair loss with poor response to therapy. Cutaneous manifestations can be specific for certain IEI, or rather unspecific. Together with clinical course and severity, they can indicate the diagnosis. Early and accurate recognition, diagnosis, and treatment are crucial for optimizing patient outcomes. The diagnosis can be determined through a detailed patient history, clinical examination, and immunological diagnostics. Collaboration between immunologists and dermatologists is vital for comprehensive care and improvement of life quality.

Genome scale CRISPR screens identify actin capping proteins as key modulators of therapeutic responses to radiation and immunotherapy

Radiotherapy (RT), is a fundamental treatment for malignant tumors and is used in over half of cancer patients. As radiation can promote anti-tumor immune effects, a promising therapeutic strategy is to combine radiation with immune checkpoint inhibitors (ICIs). However, the genetic determinants that impact therapeutic response in the context of combination therapy with radiation and ICI have not been systematically investigated. To unbiasedly identify the tumor intrinsic genetic factors governing such responses, we perform a set of genome-scale CRISPR screens in melanoma cells for cancer survival in response to low-dose genotoxic radiation treatment, in the context of CD8 T cell co-culture and with anti-PD1 checkpoint blockade antibody. Two actin capping proteins, Capza3 and Capg, emerge as top hits that upon inactivation promote the survival of melanoma cells in such settings. Capza3 and Capg knockouts (KOs) in mouse and human cancer cells display persistent DNA damage due to impaired homology directed repair (HDR); along with increased radiation, chemotherapy, and DNA repair inhibitor sensitivity. However, when cancer cells with these genes inactivated were exposed to sublethal radiation, inactivation of such actin capping protein promotes activation of the STING pathway, induction of inhibitory CEACAM1 ligand expression and resistance to CD8 T cell killing. Patient cancer genomics analysis reveals an increased mutational burden in patients with inactivating mutations in CAPG and/or CAPZA3, at levels comparable to other HDR associated genes. There is also a positive correlation between CAPG expression and activation of immune related pathways and CD8 T cell tumor infiltration. Our results unveil the critical roles of actin binding proteins for efficient HDR within cancer cells and demonstrate a previously unrecognized regulatory mechanism of therapeutic response to radiation and immunotherapy.

Spectrum of WAS gene mutations in Vietnamese patients with Wiskott-Aldrich syndrome

BACKGROUND

WAS gene mutational analysis is crucial to establish a definite diagnosis of Wiskott-Aldrich syndrome (WAS). Data on the genetic background of WAS in Vietnamese patients have not been reported.

METHODS

We recruited 97 male, unrelated patients with WAS and analyzed WAS gene mutation using Sanger sequencing technology.

RESULTS

We identified 36 distinct hemizygous pathogenic mutations, with 17 novel variants, from 38 patients in the entire cohort (39.2%). The mutational spectrum included 14 missense, 12 indel, five nonsense, four splicing, and one non-stop mutations. Most mutations appear only once, with the exception of c.37C>T (p.R13X) and c.374G>A (p.G125E) each of which occurs twice in unrelated patients.

CONCLUSION

Our data enrich the mutational spectrum of the WAS gene and are crucial for understanding the genetic background of WAS and for supporting genetic counseling.

Síndrome de Wiskott-Aldrich en España: incidencia, mortalidad y sesgo de género durante 21 años

Antecedentes

El síndrome de Wiskott-Aldrich (SWA) es un raro trastorno ligado al cromosoma X que se considera que afecta predominantemente a varones.

Objetivo

El objetivo de este estudio consistía en investigar la incidencia y la mortalidad intrahospitalaria del SWA en España, así como el sesgo de género.

Métodos

Se llevó a cabo un estudio epidemiológico retrospectivo poblacional en 97 pacientes con SWA diagnosticados en hospitales españoles entre 1997 y 2017, utilizando para ello datos del Sistema Nacional de Vigilancia de Datos Hospitalarios.

Resultados

Nuestros resultados revelaron que la incidencia anual media del SAW en España fue de 1,1 caso por cada 10 millones de habitantes (IC del 95 %, 0,45-2,33). El riesgo relativo fue mayor en los varones que en las mujeres (2,42). El diagnóstico de SWA se establece a una edad más avanzada en las mujeres (mediana de 47 años) que en los varones (mediana de 5,5 años). Únicamente los varones ingresaron en el hospital en al menos 10 ocasiones diferentes y todas las muertes se detectaron en varones. La tasa de mortalidad intrahospitalaria fue del 9,28 % en el SAW y la mayoría de las muertes se asociaron a hemorragia cerebral o infección.

Conclusiones

El SWA, una enfermedad rara, se diagnostica a una edad más avanzada en las mujeres y la mortalidad se observó exclusivamente en varones, asociada en la mayoría de los casos a hemorragia cerebral e infección.

[Wiskott-Aldrich syndrome with platelets of normal size and c.295C>T mutation of the WAS gene. Case report]

BACKGROUND

Wiskott-Aldrich syndrome is an Inborn Error of Immunity characterized by thrombocytopenia, small platelets, severe eczema, recurrent infections, tendency to autoimmune diseases and neoplasms. The diagnosis of the syndrome can be difficult, especially when platelets are of normal size.

CASE REPORT

A three-year-old male patient was referred to a specialized sector of university hospital for presenting acute otitis media that progressed to sepsis by Haemophilus influenzae. At one month of age, he had been diagnosed with autoimmune thrombocytopenia, and splenectomy was performed at two years of age. During follow-up, three hospitalizations were necessary: an infection by Streptococcus pneumoniae, which progressed to sepsis; one due to exacerbation of eczema, isolating S. epidermidis; another due to fever of undetermined origin. The tests showed normal number of platelets after splenectomy, platelets always with normal size. At age four, tests were performed: IgE 3128 Ku/L; IgA, IgG, and normal anti-polysaccharide antibodies; decreased IgM; decrease CD19, TCD4, naïve T and B; increased TCD8; normal NK. A diagnostic hypothesis of "probable" WAS was made. Genetic research has identified the c.295C>T mutation in the WAS gene.

CONCLUSIONS

The case reported expressed a new mutation in the SWA gene, characterized by clinical manifestations of the mild phenotype of Wiskott-Aldrich syndrome, with thrombocytopenia, platelets of normal size, and X-linked inheritance. It is important to establish the early diagnosis and treatment to offer a better quality of life in these patients.

A Novel Mutation Leading to Wiskott-Aldrich Syndrome in an Ethiopian Boy: a Case Report and a Review of Literature

Wiskott-Aldrich syndrome is an X-linked recessive primary immune-deficiency disorder very rarely reported from black African children. A 12-year old boy with recurrent sinopulmonary and diarrheal infections, eczema, thrombocytopenia, and low platelet volume was found by whole genome sequencing to harbor a predicted pathogenic c.1205dupC (p.Pro403Alafs*92) variant of a mutation in the WAS gene - confirming the diagnosis. This case report summarizes his presentation and management and provides a useful summary of the diagnosis and the responsible novel genetic mutation.

High ploidy large cytoplasmic megakaryocytes are hematopoietic stem cells regulators and essential for platelet production

Megakaryocytes (MK) generate platelets. Recently, we and others, have reported MK also regulate hematopoietic stem cells (HSC). Here we show high ploidy large cytoplasmic megakaryocytes (LCM) are critical negative regulators of HSC and critical for platelet formation. Using a mouse knockout model (Pf4-Srsf3^Δ/Δ) with normal MK numbers, but essentially devoid of LCM, we demonstrate a pronounced increase in BM HSC concurrent with endogenous mobilization and extramedullary hematopoiesis. Severe thrombocytopenia is observed in animals with diminished LCM, although there is no change in MK ploidy distribution, uncoupling endoreduplication and platelet production. When HSC isolated from a microenvironment essentially devoid of LCM reconstitute hematopoiesis in lethally irradiated mice, the absence of LCM increases HSC in BM, blood and spleen, and the recapitulation of thrombocytopenia. In contrast, following a competitive transplant using minimal numbers of WT HSC together with HSC from a microenvironment with diminished LCM, sufficient WT HSC-generated LCM regulates a normal HSC pool and prevents thrombocytopenia. Importantly, LCM are conserved in humans.

Microbiome and Its Dysbiosis in Inborn Errors of Immunity

Inborn errors of immunity (IEI) can present with infections, autoimmunity, lymphoproliferation, granulomas, and malignancy. IEIs are due to genetic abnormalities that disrupt normal host-immune response or immune regulation. The microbiome appears essential for maintaining host immunity, especially in patients with a defective immune system. Altered gut microbiota in patients with IEI can lead to clinical symptoms. Microbial dysbiosis is the consequence of an increase in pro-inflammatory bacteria or a reduction in anti-inflammatory bacteria. However, functional and compositional differences in microbiota are also involved. Dysbiosis and a reduced alpha-diversity are well documented, particularly in conditions like common variable immunodeficiency. Deranged microbiota is also seen in Wiskott–Aldrich syndrome, severe combined immunodeficiency, chronic granulomatous disease, selective immunoglobulin-A deficiency, Hyper IgE syndrome (HIGES), X-linked lymphoproliferative disease-2, immunodysregulation, polyendocrinopathy, enteropathy, x-linked syndrome, and defects of IL10 signalling. Distinct gastrointestinal, respiratory, and cutaneous symptoms linked to dysbiosis are seen in several IEIs, emphasizing the importance of microbiome identification. In this study, we discuss the processes that maintain immunological homeostasis between commensals and the host and the disruptions thereof in patients with IEIs. As the connection between microbiota, host immunity, and infectious illnesses is better understood, microbiota manipulation as a treatment strategy or infection prevention method would be more readily employed. Therefore, optimal prebiotics, probiotics, postbiotics, and fecal microbial transplantation can be promising strategies to restore the microbiota and decrease disease pathology in patients with IEIs.

Infections in Inborn Errors of Immunity with Combined Immune Deficiency: A Review

Enhanced susceptibility to microbes, often resulting in severe, intractable and frequent infections due to usually innocuous organisms at uncommon sites, is the most striking feature in individuals with an inborn error of immunity. In this narrative review, based on the International Union of Immunological Societies' 2022 (IUIS 2022) Update on phenotypic classification of human inborn errors of immunity, the focus is on commonly encountered Combined Immunodeficiency Disorders (CIDs) with susceptibility to infections. Combined immune deficiency disorders are usually commensurate with survival beyond infancy unlike Severe Combined Immune Deficiency (SCID) and are often associated with clinical features of a syndromic nature. Defective humoral and cellular immune responses result in susceptibility to a broad range of microbial infections. Although disease onset is usually in early childhood, mild defects may present in late childhood or even in adulthood. A precise diagnosis is imperative not only for determining management strategies, but also for providing accurate genetic counseling, including prenatal diagnosis, and also in deciding empiric treatment of infections upfront before investigation reports are available.

Inborn Errors of Immunity

Inborn errors of immunity occur in 1 in 1000 to 1 in 5000 individuals and are characterized by immune deficiency and immune dysregulation. The primary care provider (PCP) should be familiar with key features of these diagnoses including recurrent and/or severe infections, hyperinflammation, malignancy, and autoimmunity and have a low threshold to refer for evaluation. The PCP can begin a laboratory evaluation before referral by sending a complete blood count (CBC) with differential, antibody levels, vaccine titers, and possibly other tests. Management approaches vary from antibiotic prophylaxis to hematopoietic stem cell transplantation depending on the specific diagnosis.

Traffic jam within lymphocytes: A clinician's perspective

With the discovery of novel diseases and pathways, as well as a new outlook on certain existing diseases, cellular trafficking disorders attract a great deal of interest and focus. Understanding the function of genes and their products in protein and lipid synthesis, cargo sorting, packaging, and delivery has allowed us to appreciate the intricate pathophysiology of these biological processes at the molecular level and the multi-system disease manifestations of these disorders. This article focuses primarily on lymphocyte intracellular trafficking diseases from a clinician's perspective. Familial hemophagocytic lymphohistiocytosis is the prototypical disease of abnormal vesicular transport in the lymphocytes. In this review, we highlight other mechanisms involved in cellular trafficking, including membrane contact sites, autophagy, and abnormalities of cytoskeletal structures affecting the immune cell function, based on a newer classification system, along with management aspects of these conditions.

Inadequate Activation of γδT- and B-cells in Patient with Wiskott-Aldrich Syndrome (WAS) Portrayed by TRG and IGH Repertoire Analyses

Patients with Wiskott-Aldrich syndrome (WAS) harbor mutations in the WAS gene and suffer from immunodeficiency, microthrombocytopenia, and eczema. T-cells play an important role in immune response in the skin and the γδT-cells have an important role in skin homeostasis. Since WAS patients often present with eczema, we wanted to examine whether the T-cell receptor gamma (TRG) repertoire of the γδT-cells is affected in these patients. In addition, the immunoglobulin heavy chain (IGH) repertoire from genomic DNA of WAS patients was not yet studied. Thus, we sought to determine the effects that specific WAS mutations from our patients have in shaping the TRG and IGH immune repertoires. We collected clinical and genetic data on four WAS patients, each harboring a different mutation in the WAS gene. Using next-generation sequencing (NGS), we analyzed their TRG and IGH repertoires using genomic DNA isolated from their peripheral blood. We analyzed the TRG and IGH repertoire sequences to show repertoire restriction, clonal expansions, preferential utilization of specific V genes, and unique characteristics of the antigen binding region in WAS patients with eczema compared to healthy controls. Both the TRG and IGH repertoire showed diverse repertoire comparable to healthy controls on one the hand, and on the other hand, the IGH repertoire showed increased diversity, more evenly distributed repertoire and immaturity of the antigen binding region. Thus, we demonstrate by analyzing the repertoire based on genomic DNA, the various effect that WAS mutations have in shaping the TRG and IGH adaptive immune repertoires.

Dupilumab in the treatment of genodermatosis: A systematic review

Dupilumab interferes with the signaling pathways of IL-4 and IL-13 and is effective in treating atopic dermatitis. Specific genodermatoses, including Netherton syndrome, epidermolysis bullosa pruriginosa, and hyper-IgE syndrome, are Th2 skewed diseases with activation of type 2 inflammation. We performed this systematic review to investigate the therapeutic role of dupilumab in the treatment of genodermatosis. A systematic search was conducted of the PubMed, Embase, Web of Science, and Cochrane databases from inception to December 13, 2021. The review included studies with relevant terms including "dupilumab," "genodermatosis", "Netherton syndrome", "ichthyosis", "epidermolysis bullosa" and "hyper-IgE syndrome". The initial search yielded 2,888 results, of which 28 studies and 37 patients with genodermatosis were enrolled. The assessed genodermatoses included Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with genetic disorders. Most of the reported cases showed significant clinical improvement after the initiation of dupilumab treatment without major adverse events. Decreased immunoglobulin E levels and cytokine normalization have also been documented. In conclusion, Dupilumab may have a potential therapeutic role in certain genodermatoses skewed towards T helper 2 (Th2) immunity, including Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with some genetic disorders.

Confirmed diagnosis of classic Wiskott-Aldrich syndrome in East Africa: a case report

INTRODUCTION

Wiskott-Aldrich syndrome is a rare X-linked primary immunodeficiency that mostly presents with a classic triad of eczema, microthrombocytopenia, recurrent infections, and increased risk of autoimmunity/malignancies.

CASE PRESENTATION

We present an 8-month-old African male, born from nonconsanguineous parents and who presented with a history of eczematous skin rash since day 9 of life, with recurrent sinus infections, otitis media, and skin abscesses. An elder male sibling who had similar symptoms passed away during infancy. Investigations were consistent with microthrombocytopenia and significantly raised immunoglobulin E, while immunoglobulin A and immunoglobulin G were moderately elevated with normal immunoglobulin M. Genetic testing revealed the patient to be hemizygous for a pathogenic Wiskott-Aldrich syndrome gene variant (NM_000377.2:c.403C>T). He was managed conservatively with supportive treatment until he died a year later.

CONCLUSION

Despite Wiskott-Aldrich syndrome being a rare disease, it should be considered as a differential in any male child who presents with microthrombocytopenia and recurrent infections, especially in low-resource settings where genetic testing is not routinely available.

Inborn Errors of Immunity Associated with Elevated IgE

OBJECTIVE

To review the characteristic clinical and laboratory features of inborn errors of immunity that are associated with elevated IgE levels DATA SOURCE: Primary peer-reviewed literature.

STUDY SELECTION

Original research articles reviewed include interventional studies, retrospective studies, case-control studies, cohort studies and review articles related to the subject matter.

RESULTS

An extensive literature review was completed to allow for comprehensive evaluation of several monogenic inborn errors of immunity. This review includes a description of the classic clinical features, common infections, characteristic laboratory findings, specific diagnostic methods (when applicable), and genetic basis of disease of each syndrome. A comprehensive flow diagram was created to assist them in the diagnosis and evaluation of patients with elevated IgE levels who may require evaluation for an IEI.

CONCLUSION

IEI should be considered in patients with elevated IgE levels, especially if they have recurrent infections, eczematous dermatitis, malignancy, lymphoproliferation, autoimmunity, and/or connective tissue abnormalities.

Atopy as Immune Dysregulation: Offender Genes and Targets

Allergic diseases are a heterogeneous group of disorders resulting from exaggerated type 2 inflammation. Although typically viewed as polygenic multifactorial disorders caused by the interaction of several genes with the environment, we have come to appreciate that allergic diseases can also be caused by monogenic variants affecting the immune system and the skin epithelial barrier. Through a myriad of genetic association studies and high-throughput sequencing tools, many monogenic and polygenic culprits of allergic diseases have been described. Identifying the genetic causes of atopy has shaped our understanding of how these conditions occur and how they may be treated and even prevented. Precision diagnostic tools and therapies that address the specific molecular pathways implicated in allergic inflammation provide exciting opportunities to improve our care for patients across the field of allergy and immunology. Here, we highlight offender genes implicated in polygenic and monogenic allergic diseases and list targeted therapeutic approaches that address these disrupted pathways.

Autoimmunity in Primary Immunodeficiencies (PID)

Primary immunodeficiency (PID) may impact any component of the immune system. The number of PID and immune dysregulation disorders is growing steadily with advancing genetic detection methods. These expansive recognition methods have changed the way we characterize PID. While PID were once characterized by their susceptibility to infection, the increase in genetic analysis has elucidated the intertwined relationship between PID and non-infectious manifestations including autoimmunity. The defects permitting opportunistic infections to take hold may also lead the way to the development of autoimmune disease. In some cases, it is the non-infectious complications that may be the presenting sign of PID autoimmune diseases, such as autoimmune cytopenia, enteropathy, endocrinopathies, and arthritis among others, have been reported in PID. While autoimmunity may occur with any PID, this review will look at certain immunodeficiencies most often associated with autoimmunity, as well as their diagnosis and management strategies.

Eosinophilia Associated With Immune Deficiency

The differential diagnosis of eosinophilia is broad and includes infections, malignancies, and atopy as well as inborn errors of immunity (IEI). Certain types of IEIs are known to be associated with elevated numbers of eosinophils and frequently elevated serum IgE, whereas for others the degree and frequency of eosinophilia are less established. The molecular defects underlying IEI are heterogeneous and affect different pathways, which highlights the complex regulations of this cell population within the immune system. In this review, we list and discuss clinical manifestations and therapies of immune deficiency or immune dysregulation disorders associated with peripheral blood or tissue eosinophilia with or without raised IgE levels. We present illustrative case vignettes for the most common entities and propose a diagnostic algorithm aiming to help physicians systematically to evaluate patients with eosinophilia and suspicion of an underlying IEI.

Successful Allogeneic Peripheral Blood Stem Cell Transplantation in 4 Wiskott-Aldrich Syndrome Patients

BACKGROUND

Allogeneic hematopoietic stem cell transplantation is a potential curative treatment in Wiskott-Aldrich syndrome (WAS). Here, we analyzed the outcomes in 4 WAS patients who underwent this procedure with peripheral blood stem cell (PBSC) in our center.

PATIENTS AND METHODS

Four patients with severe WAS phenotype have received allogeneic hematopoietic stem cell transplantation between January 2014 and December 2019 from matched sibling donors with PBSC. Two different preparative conditioning regimens were provided: the first associated busulfan-cyclophosphamide (2 patients) and the second with busulfan-fludarabine administered to the others. Cyclosporine gave as preferred graft-versus-host disease prophylaxis with a short course of methotrexate.

RESULTS

All patients achieved engraftment after PBSC with a median CD34+ cell count: 13.6×106/kg (8 to 24.9×106/kg). Chronic graft-versus-host disease developed in 2 patients treated by cyclosporine-steroids with complete resolution. Chimerism for all the patients was fully donor (>95% donor). After a median follow-up of 41 months (8 to 74 mo), all patients (100%) are alive, healthy, with complete clinical, immunologic, and hematologic recovery, without signs of WAS.

CONCLUSION

This limited study with high-dose PBSC transplantation approach for WAS, demonstrated a safe and effective treatment option, with rapid engraftment, without complications, excellent long-term outcomes, independent of conditioning regimen.

Wiskott-Aldrich syndrome: Oral findings and microbiota in children and review of the literature

Objective

Wiskott–Aldrich syndrome (WAS) is a rare X‐linked primary immunodeficiency, characterized by micro‐thrombocytopenia, recurrent infections, and eczema. This study aims to describe common oral manifestations and evaluate oral microbioma of WAS patients.

Material and methods

In this cohort study, 11 male WAS patients and 16 male healthy controls were evaluated in our Center between 2010 and 2018. Data about clinical history, oral examination, Gingival Index (GI) and Plaque Index (PI) were collected from both groups. Periodontal microbiological flora was evaluated on samples of the gingival sulcus.

Results

WAS subjects presented with premature loss of deciduous and permanent teeth, inclusions, eruption disturbance, and significantly worse GI and PI. They also showed a trend toward a higher total bacterial load. Fusobacterium nucleatum, reported to contribute to periodontitis onset, was the most prevalent bacteria, together with Porphyromonas gingivalis and Tannerella forsythia.

Conclusions

Our data suggest that WAS patients are at greater risk of alterations in the oral cavity. The statistically higher incidence of periodontitis and the trend to higher prevalence of potentially pathological bacterial species in our small cohort, that should be confirmed in future in a larger population, underline the importance of dentistry monitoring as part of the multidisciplinary management of WAS patients.

Lymphocytes Utilize Somatic Mutations, Epigenetic Silencing, and the Proteasome to Escape Truncated WASP Expression

Wiskott-Aldrich Syndrome Protein (WASP) deficiency causes Wiskott-Aldrich Syndrome (WAS), a sex-linked disorder characterized by combined immunodeficiency, microthrombocytopenia, and eczema. Like WASP-deficient humans, WASP-deficient mice produce normal numbers of functionally defective T cells. Here, we report a WAS patient with a novel germline frameshifting WAS mutation encoding a truncated form of WASP lacking the C-terminal cofilin homology (C) and the acidic region (A) domains (WASPΔCA). Although stably overexpressed in embryonic kidney cell lines, WASPΔCA was undetectable in circulating patient leukocytes. Deep sequencing, transcript profiling, and protein degradation analyses demonstrated patient lymphocytes employ an array of genetic, epigenetic, and proteasomal strategies to avoid expressing WASPΔCA.

Clinical Features, Cancer Biology, Transplant Approach and Other Integrated Management Strategies for Wiskott-Aldrich Syndrome

Wiskott–Aldrich syndrome (WAS) is a rare X-linked recessive inborn error of immunity (IEI) first described in 1937. Classic WAS is characterized by the triad of thrombocytopenia with small platelets, recurrent infections due to combined immunodeficiency, and eczema. Hematopoietic stem cell transplantation (HSCT) was the only curative option available for five decades, with excellent outcomes reported for matched sibling donors (MSD) and matched unrelated donors (MUD). More recently, alternative donor transplants such as umbilical cord blood (UCB) and haploidentical transplant have emerged as viable options due to improvements in better graft selection, cell dosing, and effective allograft manipulation measures. Gene therapy is another potential curative option with promising results, yet currently is offered only as part of a clinical trial.

Autoimmunity in Wiskott-Aldrich Syndrome: Updated Perspectives

Wiskott–Aldrich syndrome (WAS) is an uncommon X-linked combined-immunodeficiency disorder characterized by a triad of thrombocytopenia, eczema, and immunodeficiency. Patients with WAS are also predisposed to autoimmunity and malignancy. Autoimmune manifestations have been reported in 26%–72% of patients with WAS. Autoimmunity is an independent predictor of poor prognosis and predisposes to malignancy. Development of autoimmunity is also an early pointer of the need for hematopoietic stem–cell transplantation. In this manuscript, we have collated the published data and present a narrative review on autoimmune manifestations in WAS. A summary of currently proposed immunopathogenic mechanisms and genetic variants associated with development of autoimmunity in WAS is also included.

Inborn errors of immunity manifesting as atopic disorders

Inborn errors of immunity are traditionally best known for enhancing susceptibility to infections. However, allergic inflammation, among other types of immune dysregulation, occurs frequently in patients with inborn errors of immunity. As such, the term primary atopic disorders (PADs) was recently coined to describe the group of heritable monogenic allergic disorders. It is becoming increasingly important for clinicians to recognize that allergic diseases such as food allergy, atopic dermatitis, and allergic asthma are expressions of misdirected immunity, and in patients who present with severe, early-onset, or coexisting allergic conditions, these can be indications of an underlying PAD. Identifying monogenic allergic disease through next-generation sequencing can dramatically improve outcomes by allowing the use of precision-based therapy targeting the patient's underlying molecular defect. It is therefore imperative that clinicians recognize PADs to be able to provide informed therapeutic options and improve patient outcomes. Here, we summarize the clinical features commonly seen with each of the currently known PADs, identify clinical warning signs that warrant assessment for PADs, and lastly, discuss the benefits of timely diagnosis and management of these conditions.

Atopic dermatitis is associated with hidradenitis suppurativa diagnosis: A single institution retrospective cohort study

Background

Hidradenitis suppurativa (HS) and atopic dermatitis (AD) are both chronic inflammatory skin diseases. An association between these 2 conditions can have important potential implications for elucidating pathogenesis, disease course, and treatment.

Objective

To investigate the association between AD and HS.

Methods

We performed a retrospective cohort study of patients seen at Duke University Medical Center from 2007 to 2017 who had AD compared with a control group without an AD diagnosis. The association of AD and HS was evaluated using a logistic regression model after adjusting for other confounders including age, sex, and race.

Results

Of 28,780 patients with an AD diagnosis, 325 (1.1%) were diagnosed with HS compared with 76 (0.2%) within the 48,383 patients in the non-AD group. An adjusted logistic regression model demonstrated an increased odds ratio of having HS diagnosis in the AD group as compared with the control non-AD group (odds ratio: 5.57, 95% confidence interval: 4.30-7.21, P < .001).

Limitations

This was a retrospective study performed at a single institution with the possibility of surveillance bias being present.

Conclusions

Patients with AD are more likely to be diagnosed with HS than patients without AD. Further research is needed to understand the pathophysiologic mechanism and potential treatment implications.

A Clinical Diagnosis of Wiskott Aldrich Syndrome in an Ethiopian Boy with Recurrent Sinopulmonary Infections: A Case Report

Background

Wiskott Aldrich syndrome is a primary immunodeficiency notable for eczema, recurrent infections, bleeding diathesis and microcytic thrombocytopenia.

Case

A 4½ year old boy presented with recurrent sinopulmonary infections, repeated treatment for severe eczema since infancy, thrombocytopenia with low platelet volume. His brother and uncles died during childhood due to repeated illnesses. We outline ways to diagnose and manage children in resource limited settings.

Conclusion

Wiskott Aldrich syndrome can be diagnosed by its clinical triad of syndromes. Mutation of the WASP gene confirms diagnosis. Increasing reports of primary immune deficiencies in Ethiopia call for improved education and care for clinical immunology.

Genetic predisposition to lymphomas: Overview of rare syndromes and inherited familial variants

Approximately 10 % of malignancies occur in carriers of germline mutations predisposing to cancer. A high risk of developing lymphomas has been noted in many primary immunodeficiencies, including DNA repair disorders. Moreover, implementation of next-generation sequencing has recently enabled to uncover rare genetic variants predisposing patients to lymphoid neoplasms. Some patients harboring inherited predisposition to lymphomas require dedicated clinical management, which will contribute to effective cancer treatment and to the prevention of potential severe toxicities and secondary malignancies. In line with that, our review summarizes the natural history of lymphoid tumors developing on different germline genetic backgrounds and discusses the progress that has been made toward successfully treating these malignancies.

Demographics, in-hospital analysis, and prevalence of 33 rare diseases with effective treatment in Shanghai

BACKGROUND

Rare diseases are ailments which impose a heavy burden on individual patients and global society as a whole. The rare disease management landscape is not a smooth one-a rare disease is quite often hard to diagnose, treat, and investigate. In China, the country's rapid economic rise and development has brought an increased focus on rare diseases. At present, there is a growing focus placed on the importance and public health priority of rare diseases and on improving awareness, definitions, and treatments.

METHODS

In this work we utilized clinical data from the Shanghai HIE System to characterize the status of 33 rare diseases with effective treatment in Shanghai for the time period of 2013-2016.

RESULTS AND CONCLUSION

First, we describe the total number of patients, year-to-year change in new patients with diagnosis in one of the target diseases and the distribution of gender and age for the top six (by patient number) diseases of the set of 33 rare diseases. Second, we describe the hospitalization burden in terms of in-hospital ratio, length of stay, and medical expenses during hospitalization. Finally, rare disease period prevalence is calculated for the rare diseases set.

Therapy-related acute myeloid leukemia with KMT2A-SNX9 gene fusion associated with a hyperdiploid karyotype after hemophagocytic lymphohistiocytosis

Therapy-related acute myeloid leukemia (t-AML) following treatment with topoisomerase-II inhibitors has been increasingly reported. These compounds (e.g. etoposide) promote DNA damage and are associated with KMT2A rearrangements. They are widely used as first-line treatment in hemophagocytic lymphohistiocytosis (HLH). Here we describe a newborn who developed t-AML after HLH treatment. We provide detailed clinical, cytogenetic, and molecular characteristics of this patient, including the identification of a novel gene fusion - KMT2A-SNX9 - in t-AML. Considering the dismal outcome of this case, we discuss the side-effects of etoposide administration during HLH treatment in infants.

Targeted genome editing for the correction or alleviation of primary Immunodeficiencies

Primary immunodeficiencies (PID) are a growing list of unique disorders that result in a failure of the innate/adaptive immune systems to fully respond to disease or infection. PIDs are classified into five broad categories; B cell disorders, combined B and T cell disorders, phagocytic disorders, complement disorders, and disorders with recurrent fevers and inflammation. Many of these disorders, such as X-SCID, WAS, and CGD lead to early death in children if intervention is not implemented. At present, the predominant method of curative therapy remains an allogeneic transplant from a healthy donor, however many complications and limitations exist with his therapy such as availability of donors, graft vs host disease, graft rejection, and infection. More recently, gene therapy using viral based complementation vectors have successfully been implemented to functionally correct patient cells in an autologous transplant, but these methods carry significant risks, including insertional mutagenesis, and provide non-physiological gene expression. For these reasons, gene-editing reagents such as targeted nucleases, base editors (BE), and prime editors (PE) are being explored. The BE and PE tools, sometimes referred to as digital editors, are of very high interest as they provide both enhanced molecular specificity and do not rely on DNA repair pathways after DSBs to change individual base pairs or directly replace DNA sequences responsible for pathogenic phenotypes. With this in mind the purpose of this chapter is to highlight some of the most common PIDs found within the human population, discuss successes and shortcomings of previous intervention strategies, and highlight how the next generation of gene-editing tools may be deployed to directly repair the underlying genetic causes of this class of disease.

Misdiagnosed thrombocytopenia in children and adolescents: analysis of the Pediatric and Adult Registry on Chronic ITP

Primary immune thrombocytopenia (ITP) in children is a diagnosis of exclusion, but cases of secondary ITP and nonimmune thrombocytopenia (non-IT) are generally difficult to recognize in a timely fashion. We describe a pediatric population with a revised diagnosis of secondary ITP or non-IT within 24 months of follow-up. Data were extracted from the Pediatric and Adult Registry on Chronic ITP, an international multicenter registry collecting data prospectively in patients with newly diagnosed primary ITP. Between 2004 and 2019, a total of 3974 children aged 3 months to 16 years were included. Secondary ITP and non-IT were reported in 113 patients (63 female subjects). Infectious (n = 53) and autoimmune (n = 42) diseases were identified as the main causes, with median ages at diagnosis of 3.2 years (interquartile range: 1.2; 6.7 years) and 12.4 years (interquartile range: 7.6; 13.7 years), respectively. Other causes included malignancies, aplastic anemia, immunodeficiency, and drug use. Patients with malignancy and aplastic anemia had significantly higher initial platelet counts (37 and 52 × 109/L) than did those with infection or autoimmune diseases (12 and 13 × 109/L). Characteristics of patients with secondary ITP due to infection were similar to those of children with primary ITP at first presentation, indicating similar mechanisms. Significant differences were found for age, sex, comorbidities, initial bleeding, sustained need for treatment, and disease persistence for the remaining noninfectious group compared with primary ITP. Based on our findings, we propose a diagnostic algorithm that may serve as a basis for further discussion and prospective trials.

A Novel Mutation in WAS Gene Causing a Phenotypic Presentation of Wiskott-Aldrich Syndrome: A Case Report

BACKGROUND

Wiskott-Aldrich syndrome (WAS) is an X-linked disorder characterized by immunodeficiency, thrombocytopenia, and atopic dermatitis.

OBSERVATIONS

This infant presented at birth with petechiae and bruising, with severe neonatal thrombocytopenia. Genetic testing for WAS revealed a variant of unknown significance hemizygous missense mutation in the WAS gene. This variant has not previously been reported. On the basis of the patient's clinical course including bleeding, infection, abnormal immune evaluation, and dermatologic sequelae, he was diagnosed with WAS and underwent allogeneic hematopoietic stem cell transplantation.

CONCLUSIONS

We report a novel mutation in the WAS gene that causes a phenotypic presentation of Wiskott-Aldrich Syndrome.

Inborn errors of immunity associated with characteristic phenotypes

OBJECTIVES

The aim of the report is to describe the main immunodeficiencies with syndromic characteristics according to the new classification of Inborn Errors of Immunity.

DATA SOURCE

The data search was centered on the PubMed platform on review studies, meta-analyses, systematic reviews, case reports and a randomized study published in the last 10 years that allowed the characterization of the several immunological defects included in this group.

DATA SYNTHESIS

Immunodeficiencies with syndromic characteristics include 65 immunological defects in 9 subgroups. The diversity of clinical manifestations is observed in each described disease and may appear early or later, with variable severity. Congenital thrombocytopenia, syndromes with DNA repair defect, immuno-osseous dysplasias, thymic defects, Hyper IgE Syndrome, anhidrotic ectodermal dysplasia with immunodeficiency and purine nucleoside phosphorylase deficiency were addressed.

CONCLUSIONS

Immunological defects can present with very different characteristics; however, the occurrence of infectious processes, autoimmune disorders and progression to malignancy may suggest diagnostic research. In the case of diseases with gene mutations, family history is of utmost importance.

Wiskott Aldrich syndrome: healthcare utilizations and disparities in transplant care

Wiskott Aldrich syndrome (WAS) is a rare disease and hematopoietic stem cell transplant (HCT) is considered the treatment modality of choice for WAS. We conducted a cross-sectional analysis on the KIDS' pediatric inpatient database and compared hospitalization rates, complications and healthcare utilizations in the transplant and non-transplant arms. Of the 383 pediatric admissions with diagnosis of WAS between 2006-2012, 114 underwent transplant and 269 did not. The non-transplant arm included older children, female patients and more African Americans. Death rates, income and payer source were similar in both arms, however the total charge for each admission was higher in the transplant arm. Emergency room visits were similar but non-elective admissions were more in the non-transplant arm. Length of stay was prolonged in the transplant arm. When comparing morbidities, lymphomas, ulcerative colitis and autoimmune complications of WAS were seen only in the non-transplant arm. Our study shows that transplant is the largest contributor to healthcare utilization in WAS patients. We identified healthcare disparities based on race and socioeconomic status and found that this rare disease is being appropriately directed to centers with HCT expertise. We noted a change in practice moving away from splenectomy in WAS patients.

Wiskott-Aldrich syndrome with normal platelet volume in a low-income setting: a case report

Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency X-linked genetic disorder. It is often featured with a clinical triad of thrombocytopenia with low mean platelet volume, eczematoid dermatitis and recurrent infections. The clinical manifestation of WAS, depending on the underlying variant, shows wide heterogeneity. We present a case of a 10-month-old boy who came in with a history of recurrent fever, skin lesions since birth and episodes of bloody diarrhoea. He had severe anaemia and thrombocytopenia (with normal mean platelet volume). Genetic analysis revealed the patient to be hemizygous for a pathogenic WAS gene splice variant (NM_000377.2:c.360+1G>A). He was managed with supportive treatment and regular follow up, but died 4 months later. As it is a rare genetic disease, the diagnosis of WAS can easily be missed, especially in settings with scarce healthcare resources that do not have easy access to genetic testing. Thus, a high index of suspicion is needed when a male child presents with recurrent infections and bleeding tendencies.

Plain language summary

Management challenges of a rare genetic disorder in a resource-limited country: a case report of Wiskott-Aldrich syndrome in TanzaniaWiskott-Aldrich syndrome (WAS) is a rare inherited disease that mainly affects boys. Patients will typically present with low levels of a single line of little particles of cells that clot the blood called platelets, whole-body skin rashes and recurrent infections. Nevertheless, the clinical presentation can vary between individuals. We present a case of a 10-month-old boy who came in with a history of recurrent fever, skin rash since birth and episodes of bloody diarrhoea. He had very low levels of red blood cells and platelets. Genetic analysis confirmed the patient to have WAS. He was managed with supportive treatment, followed up on a regular clinic but unfortunately died 4 months later. Being a rare genetic disease, the diagnosis of WAS can easily be missed, especially in regions with scarce healthcare resources that do not have easy access to genetic testing. Thus, doctors should suspect WAS in boys presenting with recurrent infections and bleeding problems.

Clinical Features and Outcomes of 23 Patients with Wiskott-Aldrich Syndrome: A Single-Center Experience

Objective

Wiskott-Aldrich syndrome (WAS) is an X-linked primary immune deficiency characterized by microthrombocytopenia, eczema, and recurrent infections. We aimed to evaluate the clinical features and outcomes of a WAS cohort.

Materials and Methods

We retrospectively evaluated the clinical courses, immunological features, treatments, and outcomes in a total of 23 WAS patients together with data related to 11 transplanted cases among them between 1982 and 2019.

Results

Before admission, 11 patients (48%) were misdiagnosed with immune thrombocytopenia. WAS scores were mostly 4 or 5. Eleven patients were transplanted and they had an overall survival rate of 100% during a median follow-up period of 8.5 years (range: 8 months to 20 years). Five patients who were not transplanted died at a median of 7 years (range: 2-26 years). Nontransplanted patients had high morbidity due to organ damage, mostly caused by autoimmunity, bleeding, and infections. Two novel mutations were also defined.

Conclusion

All male babies with microthrombocytopenia should be evaluated for WAS. Hematopoietic stem cell transplantation should be performed at the earliest age with the best possible donors.

Wiskott-Aldrich Syndrome in four male siblings from a consanguineous family from Lebanon

BACKGROUND

Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency disorder (PID) characterized by microthrombocytopenia, bloody diarrhea, eczema, recurrent infections, and a high incidence of autoimmunity and malignancy.

OBJECTIVE

To investigate the mechanism of thrombocytopenia and infections in four boys of consanguineous parents from Lebanon.

METHODS

Patient gDNA was studied using Next Generation Sequencing and Sanger Sequencing. Protein expression was determined by immunoblotting, and mRNA expression by semi-quantitative RT-PCR. F-actin polymerization and cellular proliferation were assayed by flow cytometry.

RESULTS

We identified a threonine to a methionine change at position 45 (T45M) of the WAS protein (WASp) that abolished protein expression and disturbed F-actin polymerization and T cell proliferation, but not B cell proliferation. In addition, the levels of the WAS-interacting protein (WIP) were significantly decreased in the patients.

CONCLUSION

The mutation identified severely destabilizes WASp and affects the downstream signaling events important for T cell function, but not B cell function. It was previously known that the stability of WASp depends on WIP. In this manuscript, we report that the stability of WIP also depends on WASp. Finally, it is important to suspect X-linked PIDs even in consanguineous families.

CLINICAL IMPLICATIONS

The patients are above the optimal age for transplant in WAS, and it is difficult to identify one or more donors for four patients, therefore, they represent ideal candidates for gene therapy or interleukin-2 therapy.

Use of Thromboelastography to Guide Platelet Infusion in a Patient with Wiskott-Aldrich Syndrome Undergoing Renal Transplant

Wiskott-Aldrich syndrome is a rare primary immuno-deficiency disorder that is characterized by a triad of microthrombocytopenia, eczema, and recurrent infections. Progression to end-stage renal failure is common in survivors due to immunoglobulin A nephropathy. We describe the case of a 24-year-old male with Wiskott-Aldrich syndrome. The patient had previous hematopoietic stem cell transplant and was on hemodialysis due to end-stage renal failure. He subsequently underwent living-donor renal transplant from his mother as the donor. This is only the fifth case of renal transplant in a patient with Wiskott-Aldrich syndrome in the world. In all cases, the perioperative management of hemostatic function has been crucial. We used thromboelastography to guide our hemostatic decisions rather than platelet count, thus reducing exposure to unnecessary platelet transfusions and without increased bleeding risk. Our patient had an uneventful course after living-donor kidney transplant.

Identifying and treating refractory ITP: difficulty in diagnosis and role of combination treatment

Immune thrombocytopenia (ITP) is the most common acquired thrombocytopenia after chemotherapy-induced thrombocytopenia. Existing guidelines describe the management and treatment of most patients who, overall, do well, even if they present with chronic disease, and they are usually not at a high risk for bleeding; however, a small percentage of patients is refractory and difficult to manage. Patients classified as refractory have a diagnosis that is not really ITP or have disease that is difficult to manage. ITP is a diagnosis of exclusion; no specific tests exist to confirm the diagnosis. Response to treatment is the only affirmative confirmation of diagnosis. However, refractory patients do not respond to front-line or other treatments; thus, no confirmation of diagnosis exists. The first section of this review carefully evaluates the diagnostic considerations in patients with refractory ITP. The second section describes combination treatment for refractory cases of ITP. The reported combinations are divided into the era before thrombopoietin (TPO) and rituximab and the current era. Current therapy appears to have increased effectiveness. However, the definition of refractory, if it includes insufficient response to TPO agents, describes a group with more severe and difficult-to-treat disease. The biology of refractory ITP is largely unexplored and includes oligoclonality, lymphocyte pumps, and other possibilities. Newer treatments, especially rapamycin, fostamatinib, FcRn, and BTK inhibitors, may be useful components of future therapy given their mechanisms of action; however, TPO agents, notwithstanding failure as monotherapy, appear to be critical components. In summary, refractory ITP is a complicated entity in which a precise specific diagnosis is as important as the development of effective combination treatments.

DNA mechanotechnology reveals that integrin receptors apply pN forces in podosomes on fluid substrates

Podosomes are ubiquitous cellular structures important to diverse processes including cell invasion, migration, bone resorption, and immune surveillance. Structurally, podosomes consist of a protrusive actin core surrounded by adhesion proteins. Although podosome protrusion forces have been quantified, the magnitude, spatial distribution, and orientation of the opposing tensile forces remain poorly characterized. Here we use DNA nanotechnology to create probes that measure and manipulate podosome tensile forces with molecular piconewton (pN) resolution. Specifically, Molecular Tension-Fluorescence Lifetime Imaging Microscopy (MT-FLIM) produces maps of the cellular adhesive landscape, revealing ring-like tensile forces surrounding podosome cores. Photocleavable adhesion ligands, breakable DNA force probes, and pharmacological inhibition demonstrate local mechanical coupling between integrin tension and actin protrusion. Thus, podosomes use pN integrin forces to sense and respond to substrate mechanics. This work deepens our understanding of podosome mechanotransduction and contributes tools that are widely applicable for studying receptor mechanics at dynamic interfaces.

Primary Immunodeficiency Disorders Among North Indian Children

OBJECTIVES

To report the distribution pattern of various categories of primary immunodeficiency disorders (PIDs) in children from North India, frequency of warning signs and critical parameters for evaluation.

METHODS

In this retrospective study, 528 children below 18 y of age after clinical assessment and presentation suggestive of PID were further screened by immunophenotyping for immune cell markers by flow cytometry.

RESULTS

A total of 120 (23%) children were diagnosed with PID with median age at diagnosis being 2.5 y in males and 3.5 y in females and an average delay in diagnosis from onset of symptoms being approximately 5 y. Chronic lower respiratory tract infections, gastrointestinal symptoms like persistent diarrhea and failure to thrive were amongst the most common warning signs in these patients. PIDs were classified according to the International Union of Immunological Societies' (IUIS) criteria. The diagnosis of index study subjects included combined humoral and cellular immunodeficiency (29%), phagocytic defects (29%), followed by predominantly antibody deficiency (18%), innate immunity and dysregulation (17%) and other well-defined syndromes (7%). A family history of PID (23%), consanguineous marriage (8%) and previous sibling death (23%) were observed as major clinical predictors/clues for underlying PID. All children received prophylactic antibiotics and/or antifungals in addition to specific therapy for underlying immune deficiency.

CONCLUSIONS

The field of PIDs in India remains largely unexplored and we are faced with various challenges in the diagnosis of PIDs due to lack of awareness as well as absence of equipped immunological laboratory support. The authors propose a methodical step-wise laboratory diagnostic approach that can facilitate early diagnosis and timely intervention of these mis/underdiagnosed disorders.