Publications by authors named "Tomoki Kawai"

Human recombination-activating gene (RAG) deficiency can manifest with distinct clinical and immunological phenotypes. By applying a multiomics approach to a large group of -mutated patients, we aimed at characterizing the immunopathology associated with each phenotype. Although defective T and B cell development is common to all phenotypes, patients with hypomorphic variants can generate T and B cells with signatures of immune dysregulation and produce autoantibodies to a broad range of self-antigens, including type I interferons.

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Negative experiences during adolescence, such as social isolation (SI), bullying, and abuse, increase the risk of psychiatric diseases in adulthood. However, the pathogenesis of psychiatric diseases induced by these factors remain poorly understood. In adolescents, stress affects the intestinal homeostasis in the gut-brain axis.

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Stressful life events contribute to the onset of major depressive disorder (MDD). We recently demonstrated abnormalities in ubiquitination in the pathophysiology of MDD. However, the underlying molecular mechanisms remain unclear.

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Recombination-activating genes (RAG1 and RAG2) are critical for lymphoid cell development and function by initiating the variable (V), diversity (D), and joining (J) (V(D)J)-recombination process to generate polyclonal lymphocytes with broad antigen specificity. The clinical manifestations of defective RAG1/2 genes range from immune dysregulation to severe combined immunodeficiencies (SCIDs), causing life-threatening infections and death early in life without hematopoietic cell transplantation (HCT). Despite improvements, haploidentical HCT without myeloablative conditioning carries a high risk of graft failure and incomplete immune reconstitution.

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Interpreting genetic changes observed in individual patients is a critical challenge. The array of immune deficiency syndromes is typically caused by genetic variation unique to individuals. Therefore, new approaches are needed to interpret functional variation and accelerate genomics interpretation.

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Paired box 1 (PAX1) deficiency has been reported in a small number of patients diagnosed with otofaciocervical syndrome type 2 (OFCS2). We described six new patients who demonstrated variable clinical penetrance. Reduced transcriptional activity of pathogenic variants confirmed partial or complete PAX1 deficiency.

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Article Synopsis
  • The article discusses the discovery of germline biallelic null mutations in the ARPC5 gene, affecting the Arp2/3 actin nucleator complex, in two patients with severe recurrent infections, early-onset autoimmunity, and other health issues.
  • The mutations lead to compromised functions across multiple cell types, but restoring protein expression in vitro can rescue the complex's conformation and functions.
  • The study reveals that IL-6 signaling is uniquely affected, with important distinctions between classical and trans-signaling pathways, suggesting potential therapeutic targets for treatment.
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Purpose: Biallelic loss-of-function variants in IKBKB cause severe combined immunodeficiency. We describe a case of autoimmunity and autoinflammation in a male infant with a heterozygous gain-of-function (GOF) IKBKB variant.

Methods: Case report and review of the literature.

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The recombination-activating genes (RAG) 1 and 2 are indispensable for diversifying the primary B cell receptor repertoire and pruning self-reactive clones via receptor editing in the bone marrow; however, the impact of RAG1/RAG2 on peripheral tolerance is unknown. Partial RAG deficiency (pRD) manifesting with late-onset immune dysregulation represents an 'experiment of nature' to explore this conundrum. By studying B cell development and subset-specific repertoires in pRD, we demonstrate that reduced RAG activity impinges on peripheral tolerance through the generation of a restricted primary B cell repertoire, persistent antigenic stimulation and an inflammatory milieu with elevated B cell-activating factor.

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Article Synopsis
  • Pediatric COVID-19 (pCOVID-19) usually has mild symptoms, but some children may develop a serious condition called multisystem inflammatory syndrome in children (MIS-C), which can lead to significant health problems.
  • A study analyzed 110 children with COVID-19, 76 with MIS-C, and 76 healthy controls using advanced techniques to understand their immune responses and genetic factors.
  • The findings revealed different immune signatures between pCOVID-19 and MIS-C, suggesting that these conditions have distinct biological pathways, which could help in developing targeted treatments.
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Major depressive disorder (MDD) is a common and serious psychiatric disease that involves brain inflammation. Bifidobacterium breve is commonly used as a probiotic and was shown to improve colitis and allergic diseases by suppressing the inflammatory response. Heat-sterilized B.

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Article Synopsis
  • The SASH3 protein is an adaptor involved in orchestrating signaling in lymphocytes, and its gene is located on the X-chromosome.
  • Researchers found 3 harmful mutations in the SASH3 gene in 4 unrelated male patients who displayed symptoms of combined immunodeficiency and immune dysregulation, leading to infections and autoimmune issues.
  • The study reveals that SASH3 is crucial for proper lymphocyte function and survival, suggesting a new form of X-linked combined immunodeficiency in humans similar to defects seen in mouse models.
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Variants in recombination-activating genes () are common genetic causes of autosomal recessive forms of combined immunodeficiencies (CID) ranging from severe combined immunodeficiency (SCID), Omenn syndrome (OS), leaky SCID, and CID with granulomas and/or autoimmunity (CID-G/AI), and even milder presentation with antibody deficiency. We aim to estimate the incidence, clinical presentation, genetic variability, and treatment outcome with geographic distribution of patients with the defects in populations inhabiting South, West, and East Slavic countries. Demographic, clinical, and laboratory data were collected from -deficient patients of Slavic origin via chart review, retrospectively.

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Article Synopsis
  • * Results showed that AK2 deficiency and a null IL2RG mutation led to early T-cell development blocks, while a missense IL2RG mutation allowed for some maturation despite lower cell numbers.
  • * The ATO system proves useful in distinguishing between hematopoietic and thymic defects in T-cell deficiency and identifying specific stages where T-cell differentiation is hindered.
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Familial hemophagocytic lymphohistiocytosis (FHL) type 3 is a life-threatening immune dysregulation syndrome caused by mutations in the UNC13D gene, encoding the munc13-4 protein, which is important for function of cytotoxic lymphocytes. FHL3 accounts for 30-40% of FHL cases, and more than 100 mutations in the UNC13D gene have been described to date. We describe the first case of FHL3 carrying an intragenic duplication of UNC13D, apparently mediated by recombination of Alu elements.

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Familial hemophagocytic lymphohistiocytosis (FHL) is the major form of hereditary hemophagocytic lymphohistiocytosis (HLH); as such, it requires prompt and accurate diagnosis. We previously reported that FHL type 3 (FHL3) can be rapidly screened by detecting munc13-4 expression in platelets using flow cytometry; however, the reliability of the munc13-4 expression assay for FHL3 diagnosis is unclear. Regardless of the type of mutation, all reported FHL3 cases examined for the munc13-4 protein showed significantly reduced expression.

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Objectives: Mevalonate kinase deficiency (MKD), a rare autosomal recessive autoinflammatory syndrome, is caused by disease-causing variants of the mevalonate kinase (MVK) gene. A national survey was undertaken to investigate clinical and genetic features of MKD patients in Japan.

Methods: The survey identified ten patients with MKD.

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Introduction: Filamin A (FLNA) is located in Xq28, and encodes the actin binding protein, filamin A. A mutation in FLNA is the most common cause of periventricular nodular heterotopia (PVNH), but a clear phenotype-genotype correlation has not been established. Indeed, some patients with a FLNA mutation have recently been shown to additionally have Ehlers-Danlos-like collagenopathy or macrothrombocytopenia.

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Rationale: Tricho-hepato-enteric syndrome (THES) is a rare disorder caused by mutations in the TTC37 or SKIV2L genes and characterized by chronic diarrhea, liver disease, hair abnormalities, and high mortality in early childhood due to severe infection or liver cirrhosis.

Patient Concerns: The patient is the second child of three siblings born to non-consanguineous healthy Japanese parents. She had intrauterine growth retardation and was delivered at 33 weeks of gestation due to placental abruption.

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Autoinflammatory diseases occupy one of a group of primary immunodeficiency diseases that are generally thought to be caused by mutation of genes responsible for innate immunity, rather than by acquired immunity. Mutations related to autoinflammatory diseases occur in 12 genes. For example, low-level somatic mosaic NLRP3 mutations underlie chronic infantile neurologic, cutaneous, articular syndrome (CINCA), also known as neonatal-onset multisystem inflammatory disease (NOMID).

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Purpose: Anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) is caused by mutations in the NF-κB essential modulator (NEMO) or NF-κB inhibitor, alpha (IKBA) genes. A heterozygous NEMO mutation causes incontinentia pigmenti (IP) in females, while a hemizygous hypomorphic mutation of NEMO causes EDA-ID in males. In general, immunodeficiency is not shown in IP patients.

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