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Ataxia-telangiectasia (A-T) is an autosomal recessive chromosomal breakage syndrome caused by mutation of the ATM (A-T mutated) gene, which encodes a protein kinase that has a major role in the cellular response to DNA damage. Approximately, 10% of A-T patients develop lymphoid malignancies. Deaths caused by extreme sensitivity to chemotherapy for malignancy have been reported, and cancer treatment in A-T is extraordinarily difficult, needing careful monitoring and individualized protocols. We report the case of a 12-year-old girl with A-T diagnosed at the age of 3 in association with IgA deficiency and recurrent pulmonary infections. Sanger sequencing revealed compound heterozygosity of the ATM gene, which bore two novel mutations. At the age of 12, she developed stage IV T-cell/histiocyte-rich large B-cell lymphoma. The tumor was resistant to chemotherapy, and she unfortunately died of cardiac insufficiency and multiple organ failure induced by rapid progression of the disease. The treatment approach for children with A-T and advanced-stage B-non-Hodgkin lymphoma must be refined.

IRAK4 deficiency is an inborn error of immunity predisposing patients to invasive pyogenic infections. Currently, there is no established simple assay that enables precise characterization of IRAK4 mutant alleles in isolation. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune condition that is characterized by psychiatric symptoms, involuntary movement, seizures, autonomic dysfunction, and central hypoventilation. It typically occurs in adult females associated with tumors. Only a few infantile cases with anti-NMDAR encephalitis have been so far reported. We identified a 10-month-old boy with IRAK4 deficiency presenting with anti-NMDAR encephalitis and human herpes virus 6 (HHV6) reactivation. The diagnosis of IRAK4 deficiency was confirmed by the identification of compound heterozygous mutations c.29_30delAT (p.Y10Cfs*9) and c.35G>C (p.R12P) in the IRAK4 gene, low levels of IRAK4 protein expression in peripheral blood, and defective fibroblastic cell responses to TLR and IL-1 (TIR) agonist. We established a novel NF-κB reporter assay using IRAK4-null HEK293T, which enabled the precise evaluation of IRAK4 mutations. Using this system, we confirmed that both novel mutations identified in the patient are deleterious. Our study provides a new simple and reliable method to analyze IRAK4 mutant alleles. It also suggests the possible link between inborn errors of immunity and early onset anti-NMDAR encephalitis. Electronic supplementary material The online version of this article (10.1007/s10875-020-00885-5) contains supplementary material, which is available to authorized users.

Heterozygous gain-of-function (GOF) mutations in STAT1 in patients with chronic mucocutaneous candidiasis (CMC) and hypothyroidism were discovered in 2011. CMC is the recurrent or persistent mucocutaneous infection by Candida fungi, and hypothyroidism results from autoimmune thyroiditis. Patients with these diseases develop other infectious diseases, including viral, bacterial, and fungal diseases, and other autoimmune manifestations, including enterocolitis, immune cytopenia, endocrinopathies, and systemic lupus erythematosus. STAT1-GOF mutations are highly penetrant with a median age at onset of 1 year and often underlie an autosomal dominant trait. As many as 105 mutations at 72 residues, including 65 recurrent mutations, have already been reported in more than 400 patients worldwide. The GOF mechanism involves impaired dephosphorylation of STAT1 in the nucleus. Patient cells show enhanced STAT1-dependent responses to type I and II interferons (IFNs) and IL-27. This impairs Th17 cell development, which accounts for CMC. The pathogenesis of autoimmunity likely involves enhanced type I IFN responses, as in other type I interferonopathies. The pathogenesis of other infections, especially those caused by intramacrophagic bacteria and fungi, which are otherwise seen in patients with diminished type II IFN immunity, has remained mysterious. The cumulative survival rates of patients with and without severe disease (invasive infection, cancer, and/or symptomatic aneurysm) at 60 years of age are 31% and 87%, respectively. Severe autoimmunity also worsens the prognosis. The treatment of patients with STAT1-GOF mutations who suffer from severe infectious and autoimmune manifestations relies on hematopoietic stem cell transplantation and/or oral JAK inhibitors., SO acknowledges Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (16H05355 and 19H03620), the Promotion of Joint International Research from the Japan Society for the Promotion of Science (18KK0228), and the Practical Research Project for Rare/Intractable Diseases from the Japan Agency for Medical Research and Development, AMED. KM acknowledges a fellowship grant from the Japan Foundation for Pediatric Research and the EURO CMC grant (ANR-14-RARE-0005-02). JLC acknowledges the National Institutes of Health grants (grant no. R01AI127564). AP acknowledges grants from the French National Research Agency (ANR) under the “Lymphocyte T helper (Th) cell differentiation in patients with inborn errors of immunity to Mycobacterium and/or Candida species” program (ANR-FNS LTh-MSMD-CMCD, ANR-18-CE93-0008-01).

Signal transducer and activator of transcription 1 gain-of-function (STAT1 GOF) mutations are the most common cause of chronic mucocutaneous candidiasis (CMC). We report the effect of oral ruxolitinib, an inhibitor of Janus kinase (JAK) family tyrosine kinases, on the clinical and immune status of a 3-year-old male with steroid-dependent severe autoimmunity due to a STAT1 GOF T385M mutation. The patient's susceptibility to infection improved with antimicrobial prophylaxis and immunoglobulin replacement therapy, but he continued to exhibit severely disabling symptoms of autoimmunity. More than one-third of patients with STAT1 GOF mutations present with autoimmune manifestations, and this patient's mutation was reported to cause CMC with autoimmunity. We analyzed the interleukin (IL)-17A and IFN-γ levels and immunophenotype by flow cytometry before and during treatment with ruxolitinib. The peripheral IL-17A level did not increase, but the IFN-γ level decreased after 4 months of therapy. The STAT1 phosphorylation level decreased significantly upon stimulation of patient cells with IFN-γ. Clinically, cytomegalovirus reactivation occurred, but was controlled. No other adverse effect was noted. We report the potential of JAK1/2 inhibition with ruxolitinib for both CMC and steroid-dependent autoimmunity. However, long-term administration is necessary, as the effect is not sustained after treatment is discontinued.

International audience; Human USP18 is an interferon (IFN)-stimulated gene product and a negative regulator of type I IFN (IFN-I) signaling. It also removes covalently linked ISG15 from proteins, in a process called deISGylation. In turn, ISG15 prevents USP18 from being degraded by the proteasome. Autosomal recessive complete USP18 deficiency is life-threatening in infancy owing to uncontrolled IFN-I–mediated autoinflammation. We report three Moroccan siblings with autoinflammation and mycobacterial disease who are homozygous for a new USP18 variant. We demonstrate that the mutant USP18 (p.I60N) is normally stabilized by ISG15 and efficient for deISGylation but interacts poorly with the receptor-anchoring STAT2 and is impaired in negative regulation of IFN-I signaling. We also show that IFN-γ–dependent induction of IL-12 and IL-23 is reduced owing to IFN-I–mediated impairment of myeloid cells to produce both cytokines. Thus, insufficient negative regulation of IFN-I signaling by USP18-I60N underlies a specific type I interferonopathy, which impairs IL-12 and IL-23 production by myeloid cells, thereby explaining predisposition to mycobacterial disease.

In this study, we performed a retrospective analysis of a cohort of Japanese paediatric patients with B-cell precursor (BCP)-acute lymphoblastic leukaemia (ALL) treated with a Berlin-Frankfurt-Münster (BFM)95-based protocol, to clarify the incidence, clinical characteristics, and risk factors of osteonecrosis (ON) in comparison to the ALL-02 protocol. We identified a high frequency of ON with the BFM95-based protocol compared to the ALL-02 protocol. The incidence of symptomatic ON with the BFM95-based protocol is comparable to previous studies in Western countries. We believe that the type of treatment regimen has more impact on the incidence of symptomatic ON in paediatric ALL than ethnicity.

Patients with autosomal recessive protein kinase C delta (PKC delta) deficiency suffer from childhood-onset autoimmunity, including systemic lupus erythematosus. They also suffer from recurrent infections that overlap with those seen in patients with chronic granulomatous disease (CGD), a disease caused by defects of the phagocyte NADPH oxidase and a lack of reactive oxygen species (ROS) production. We studied an international cohort of 17 PKC delta-deficient patients and found that their EBV-B cells and monocyte-derived phagocytes produced only small amounts of ROS and did not phosphorylate p40(phox) normally after PMA or opsonized Staphylococcus aureus stimulation. Moreover, the patients' circulating phagocytes displayed abnormally low levels of ROS production and markedly reduced neutrophil extracellular trap formation, altogether suggesting a role for PKC delta in activation of the NADPH oxidase complex. Our findings thus show that patients with PKC delta deficiency have impaired NADPH oxidase activity in various myeloid subsets, which may contribute to their CGD-like infectious phenotype. Yale Center for Mendelian Genomics - National Human Genome Research Institute [UM1HG006504]; National Institute of Allergy and Infectious DiseasesUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Allergy & Infectious Diseases (NIAID) [5R01AI089970, 5R37AI095983, R01AI127564-01]; National Center for Research ResourcesUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Center for Research Resources (NCRR); National Center for Advancing Translational Sciences of the National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Center for Advancing Translational Sciences (NCATS) [8UL1TR001866]; Rockefeller University; St. Giles Foundation; INSERMInstitut National de la Sante et de la Recherche Medicale (Inserm)European Commission; University of Paris; French Foundation for Medical ResearchFondation pour la Recherche Medicale [EQU201903007798]; Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence [ANR-10-LABX-62-IBEID]; SCOR Corporate Foundation for Science; French National Research Agency (ANR) under the Investments for the future programFrench National Research Agency (ANR) [ANR-10-IAHU-01]; ANR-IFNPHOX [ANR-13-ISV3-0001-01]; ANR-GENMSMDFrench National Research Agency (ANR) [ANR-16-CE17-0005-01]; ANR-GENCMCD [ANR-11-BSV3-005-01]; ANR-HGDIFDFrench National Research Agency (ANR) [ANR-14-CE15-0006-01]; Bettencourt Schueller Foundation; International PhD program of the Imagine Institute; Japanese Foundation; EURO-CMC project [ANR-14-RARE-0005-02]; Societe Nationale Francaise de Medecine Interne (Bourse Marcel Simon); INSERM PhD program for medical doctors (poste d'accueil INSERM); Fulbright grant (Franco-American commission); MD-PhD program of Imagine Institute; Consejo Nacional de Ciencia y Tecnologa National PhD Fellowship Program; National Institute for Health Research Biomedical Research CentreNational Institute for Health Research (NIHR); Great Ormond Street Hospital Charity; Deutsche Forschungsgemeinschaft under Germany's Excellence StrategyGerman Research Foundation (DFG) [EXC 2155, 390874280]; REBIRTH Center for Translational Regenerative Medicine through the State of Lower Saxony [MWK: ZN3440] This paper is dedicated to the memory of Prof. Asghar Agha-mohammadi, who passed away in November 2020, and made immense contributions to the understanding and treatment of primary immunodeficiencies. We thank all patients, their relatives, and the treatment teams for their cooperation in this study. We thank all the members of the Laboratory of Human Genetics of Infectious Diseases for helpful discussions. We also thank Christine Rivalain, Cecile Pa-tissier, Lazaro Lorenzo-Diaz, Dominick Papandrea, Dana Liu, and Yelena Nemirovskaya for administrative assistance and Gaspard Kerner for statistical advice. We thank the Necker Institute Imaging Facility for technical advice. The graphical abstract was created with BioRender.com under subscription. This research was supported by the Yale Center for Mendelian Genomics funded by the National Human Genome Research Insti-tute (UM1HG006504) . The Howard Hughes Medical Institute lab-oratory was funded in part by the National Institute of Allergy and Infectious Diseases (grants 5R01AI089970, 5R37AI095983, and R01AI127564-01) , the National Center for Research Resources, and the National Center for Advancing Translational Sciences of the National Institutes of Health (grant 8UL1TR001866 for J-L. Casa-nova) , the Rockefeller University, the St. Giles Foundation, INSERM, the University of Paris, the French Foundation for MedicalResearch (EQU201903007798) , the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (ANR-10-LABX-62-IBEID) , the SCOR Corporate Foundation for Science, and the French National Research Agency (ANR) under the Investments for the future program (grant ANR-10-IAHU-01) , ANR-IFNPHOX (grant ANR-13-ISV3-0001-01 for J. Bustamante) , ANR-GENMSMD (grant ANR-16-CE17-0005-01 for J. Bustamante) , ANR-GENCMCD (grant ANR-11-BSV3-005-01 for A. Puel) , and ANR-HGDIFD (grant ANR-14-CE15-0006-01 for J. Bustamante) . A-L. Neehus was sup-ported by the Bettencourt Schueller Foundation and the Interna-tional PhD program of the Imagine Institute, K. Moriya by a Japanese Foundation for Pediatric Research fellowship grant and EURO-CMC project (grant ANR-14-RARE-0005-02 for J. Bustamante) , R. Levy by the Societe Nationale Francaise de Medecine Interne (Bourse Marcel Simon) , the INSERM PhD program for medical doctors (poste d'accueil INSERM) , and the Fulbright grant (Franco-American commission) , T. Le Voyer by the Bettencourt Schueller Foundation and the MD-PhD program of Imagine Institute, and A. Nieto-Patlan by the Consejo Nacional de Ciencia y Tecnologa Na-tional PhD Fellowship Program. All research at the Great Ormond Street Hospital National Health Service Foundation Trust is sup-ported by the National Institute for Health Research Biomedical Research Centre. P.A. Brogan also acknowledges support from the Great Ormond Street Hospital Charity. N. Lachmann acknowledges support from the Deutsche Forschungsgemeinschaft under Ger-many's Excellence Strategy-EXC 2155-project number 390874280 and the REBIRTH Center for Translational Regenerative Medicine funded through the State of Lower Saxony (MWK: ZN3440) . Author contributions: A-L. Neehus, J-L. Casanova, A. Puel, and J. Bustamante conceived and designed the study. A-L. Neehus, K. Moriya, T. Le Voyer, A. Nieto-Patlan, R. Levy, M. Roynard, K. Haake, M. Migaud, and K. Dorgham performed the experiments. A. ozen, E. Karakoc-Aydiner, S. Baris, A. Yildiran, E. Altundag, F. Dogu, S. Has-kologlu, E. Ince, G. Uzel, A. Kiykim, K. Boztug, M.R. Roderick, M. Shahrooei, P.A. Brogan, H. Abolhassani, G. Hancioglu, N. Parvaneh, A.; Belot, and A. Ikinciogullari were the treating physicians respon-sible for clinical diagnosis, deep phenotyping, sample collection, and patient follow-up. G. Gorochov, L. Abel, N. Lachmann, J. El-Benna, and A. Belot provided conceptual advice. A-L. Neehus, J-L. Casanova, A. Puel, and J. Bustamante analyzed the results and wrote the man-uscript. All authors revised the manuscript and approved the final manuscript as submitted. Disclosures: P.A. Brogan reported personal fees from Sobi, No-vartis, Roche, and GSK, and grants from Sobi outside the sub-mitted work. No other disclosures were reported.

We studied a child with severe viral, bacterial, fungal, and parasitic diseases, who was homozygous for a loss-of-function mutation of REL, encoding c-Rel, which is selectively expressed in lymphoid and myeloid cells. The patient had low frequencies of NK, effector memory cells reexpressing CD45RA (Temra) CD8(+) T cells, memory CD4(+) T cells, including Th1 and Th1*, Tregs, and memory B cells, whereas the counts and proportions of other leukocyte subsets were normal. Functional deficits of myeloid cells included the abolition of IL-12 and IL-23 production by conventional DC1s (cDC1s) and monocytes, but not cDC2s. c-Rel was also required for induction of CD86 expression on, and thus antigen-presenting cell function of, cDCs. Functional deficits of lymphoid cells included reduced IL-2 production by naive T cells, correlating with low proliferation and survival rates and poor production of Th1, Th2, and Th17 cytokines by memory CD4(+) T cells. In naive CD4(+) T cells, c-Rel is dispensable for early IL2 induction but contributes to later phases of IL2 expression. The patient’s naive B cells displayed impaired MYC and BCL2L1 induction, compromising B cell survival and proliferation and preventing their differentiation into Ig-secreting plasmablasts. Inherited c-Rel deficiency disrupts the development and function of multiple myeloid and lymphoid cells, compromising innate and adaptive immunity to multiple infectious agents.

[No abstract available], Japanese Ministry of Health, Labour and Welfare of JapanMinistry of Health, Labour and Welfare, Japan [19K23819]; French National Research Agency (ANR) under the EURO-CMC projectFrench National Research Agency (ANR) [ANR-14-RARE-0005-02]; MEXT KAKENHIMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific Research (KAKENHI) [JP18K07840]; Ministry of Health, Labour and Welfare of JapanMinistry of Health, Labour and Welfare, Japan [17933688, 17933299], Kunihiko Moriya was supported by a grant from the Japanese Ministry of Health, Labour and Welfare of Japan (Grant Number 19K23819), and the French National Research Agency (ANR) under the EURO-CMC project (Grant Number ANR-14-RARE-0005-02 to Dr. Anne Puel). Hidenori Ohnishi was supported by MEXT KAKENHI Grant Number JP18K07840 and Health and Labour Science Research Grants for Research on Intractable Diseases from the Ministry of Health, Labour and Welfare of Japan (Grant Numbers 17933688 and 17933299).

Biallelic loss-of-function (LOF) mutations of the NCF4 gene, encoding the p40phox subunit of the phagocyte NADPH oxidase, have been described in only 1 patient. We report on 24 p40phox-deficient patients from 12 additional families in 8 countries. These patients display 8 different in-frame or out-of-frame mutations of NCF4 that are homozygous in 11 of the families and compound heterozygous in another. When overexpressed in NB4 neutrophil-like cells and EBV-transformed B cells in vitro, the mutant alleles were found to be LOF, with the exception of the p.R58C and c.120_134del alleles, which were hypomorphic. Particle-induced NADPH oxidase activity was severely impaired in the patients' neutrophils, whereas PMA-induced dihydrorhodamine-1,2,3 (DHR) oxidation, which is widely used as a diagnostic test for chronic granulomatous disease (CGD), was normal or mildly impaired in the patients. Moreover, the NADPH oxidase activity of EBV-transformed B cells was also severely impaired, whereas that of mononuclear phagocytes was normal. Finally, the killing of Candida albicans and Aspergillus fumigatus hyphae by neutrophils was conserved in these patients, unlike in patients with CGD. The patients suffer from hyperinflammation and peripheral infections, but they do not have any of the invasive bacterial or fungal infections seen in CGD. Inherited p40phox deficiency underlies a distinctive condition, resembling a mild, atypical form of CGD. ispartof: JOURNAL OF CLINICAL INVESTIGATION vol:128 issue:9 pages:3957-3975 ispartof: location:United States status: published

Background Autosomal dominant anhidrotic ectodermal dysplasia with immune deficiency (AD EDA-ID) is caused by heterozygous point mutations at or close to serine 32 and serine 36 or N-terminal truncations in IκBα that impair its phosphorylation and degradation and thus activation of the canonical nuclear factor κ light chain enhancer of activated B cells (NF-κB) pathway. The outcome of hematopoietic stem cell transplantation is poor in patients with AD EDA-ID despite achievement of chimerism. Mice heterozygous for the serine 32I mutation in IκBα have impaired noncanonical NF-κB activity and defective lymphorganogenesis. Objective We sought to establish genotype-phenotype correlation in patients with AD EDA-ID. Methods A disease severity scoring system was devised. Stability of IκBα mutants was examined in transfected cells. Immunologic, biochemical, and gene expression analyses were performed to evaluate canonical and noncanonical NF-κB signaling in skin-derived fibroblasts. Results Disease severity was greater in patients with IκBα point mutations than in those with truncation mutations. IκBα point mutants were expressed at significantly higher levels in transfectants compared with truncation mutants. Canonical NF-κB–dependent IL-6 secretion and upregulation of the NF-κB subunit 2/p100 and RELB proto-oncogene, NF-κB subunit (RelB) components of the noncanonical NF-κB pathway were diminished significantly more in patients with point mutations compared with those with truncations. Noncanonical NF-κB–driven generation of the transcriptionally active p100 cleavage product p52 and upregulation of CCL20 , intercellular adhesion molecule 1 (ICAM1) , and vascular cell adhesion molecule 1 (VCAM1) , which are important for lymphorganogenesis, were diminished significantly more in LPS plus α-lymphotoxin β receptor–stimulated fibroblasts from patients with point mutations compared with those with truncations. Conclusions IκBα point mutants accumulate at higher levels compared with truncation mutants and are associated with more severe disease and greater impairment of canonical and noncanonical NF-κB activity in patients with AD EDA-ID.

Notch1 mutations are found in more than 50% of human T cell acute lymphoblastic leukemia (T-ALL) cells. However, the functions of Notch1 for human T cell development and leukemogenesis are not well understood. To examine the role of Notch1, human hematopoietic stem cells (HSCs), which had been transduced with a constitutively active form of Notch1 (ICN1), were transplanted into severely immunodeficient NOD/Shi-scid-IL2rγ(null) (NOG) mice. We found that the great majority of the ICN1-expressing hematopoietic cells in the bone marrow expressed surface markers for T cells, such as CD3, CD4, and CD8, and that this T cell development was independent of the thymus. Accordingly, phenotypically mature CD8(+) single positive (SP) T cells were observed in the spleen. Furthermore, T-ALL developed in one NOG recipient mouse out of 26 that had been secondary transferred with the T cells developed in the first NOG mice. These results indicate that Notch1 signaling in HSCs promotes CD8(+) SP T cell development, and that T cell leukemogenesis may require additional oncogenic factors other than Notch1 activation.

We report on a 24-year-old woman who was diagnosed as having Maffucci syndrome with anaplastic astrocytoma. We analyzed the IDH1 and IDH2 mutations of enchondroma, hemangioma and anaplastic astrocytoma tissues and the same somatic mosaic mutation in IDH2 gene was identified in all these tissues. In addition, we identified additional mutation of the TP53 gene in anaplastic astrocytoma tissue but not in other benign tumors. This is the first report of the detection of an identical IDH2 mutation in multiple tissues and TP53 mutation in anaplastic astrocytoma in a patient with Maffucci syndrome. This case is unique and supports the IDH2-dependent genetic pathway and second-hit model for gliomagenesis.

Mutations in genes critical for surfactant metabolism, including surfactant protein C (SP-C) and ABCA3, are well-recognized causes of interstitial lung disease. Recessive mutations in ABCA3 were first attributed to fatal respiratory failure in full-term neonates, but they are also increasingly being recognized as a cause of respiratory disorders with less severe phenotypes in older children and also adults. Here, we report a 20-month-old boy with interstitial lung disease caused by two distinct ABCA3 mutations. Initial treatment with methylprednisolone was unsuccessful, but the additional administration of hydroxychloroquine was effective. The family history revealed that the patient’s older brother had died of idiopathic interstitial lung disease at 6 months of age, suggesting a genetic etiology of the disease. Sequence analyses of SP-C and ABCA3 genes were performed using DNA samples from the patient himself, his parents, and his brother. These analyses revealed novel compound heterozygous mutations in the coding exons of ABCA3 in both the patient and his brother: c.2741A > G, of paternal origin, and c.3715_3716insGGGGGG, of maternal origin. Conclusion Since ABCA3 mutations seem to be a heterogeneous entity with various phenotypes, we recommend genetic testing for mutations in SP-C and ABCA3 genes to be considered in children with unexplained interstitial lung disease.

Chronic mucocutaneous candidiasis (CMC) is defined as recurrent or persistent infection of the skin, nails, and/or mucosae with commensal Candida species. The first genetic etiology of isolated CMC-autosomal recessive (AR) IL-17 receptor A (IL-17RA) deficiency-was reported in 2011, in a single patient. We report here 21 patients with complete AR IL-17RA deficiency, including this first patient. Each patient is homozygous for 1 of 12 different IL-17RA alleles, 8 of which create a premature stop codon upstream from the transmembrane domain and have been predicted and/or shown to prevent expression of the receptor on the surface of circulating leukocytes and dermal fibroblasts. Three other mutant alleles create a premature stop codon downstream from the transmembrane domain, one of which encodes a surface-expressed receptor. Finally, the only known missense allele (p.D387N) also encodes a surface-expressed receptor. All of the alleles tested abolish cellular responses to IL-17A and -17F homodimers and heterodimers in fibroblasts and to IL-17E/IL-25 in leukocytes. The patients are currently aged from 2 to 35 y and originate from 12 unrelated kindreds. All had their first CMC episode by 6 mo of age. Fourteen patients presented various forms of staphylococcal skin disease. Eight were also prone to various bacterial infections of the respiratory tract. Human IL-17RA is, thus, essential for mucocutaneous immunity to Candida and Staphylococcus, but otherwise largely redundant. A diagnosis of AR IL-17RA deficiency should be considered in children or adults with CMC, cutaneous staphylococcal disease, or both, even if IL-17RA is detected on the cell surface.

Genetic mosaicism for somatic mutations of oncogenes is common in genodermatoses, which can be complicated with extra-cutaneous abnormalities. Here we describe an infant with a congenital anaplastic astrocytoma, a linear syringocystadenoma papilliferum, and ocular abnormalities. The BRAF c.1799T>A p.V600E mutation was detected in both the brain and skin tumor cells but not in the blood or normal skin cells, suggesting somatic mosaicsism for the mutation. Clinically, the brain tumor gradually became life threatening without any response to conventional chemotherapies including carboplatin, etoposide, and temozolomide. Vemurafenib, a BRAF p.V600E inhibitor, was administered daily after the detection of the BRAF mutation. This single-agent therapy was dramatically effective against the anaplastic astrocytoma; the tumor regressed, the cerebrospinal fluid cell count and protein levels decreased to normal levels, and hydrocephalus resolved. Moreover, other lesions including a corneal cyst also responded to vemurafenib. The brain tumor continued shrinking after 6 months of treatment. We present a genodermatosis syndrome associated with BRAF c.1799T>A p.V600E mosaicism. This syndrome may represent a new entity in the mosaic RASopathies, partly overlapping with Schimmelpenning-Feuerstein-Mims syndrome, which is driven by mosaicism of HRAS and/or KRAS activating mutations. Screening for BRAF c.1799T>A p.V600E is especially useful for those with malignant tumors, because it is one of the most-druggable targets.

Autoimmune hemolytic anemia (AIHA) is a rare disease in infants, for which steroids are recognized as a first-line therapy for patients. Rituximab, a humanized monoclonal antibody raised against CD20, has been used in the treatment of autoimmune diseases, including AIHA, in adults and children. Due to limited follow-up study of the use of rituximab in the treatment for AIHA, its long-term efficacy, adverse effects, and immunological reconstitution of B cells have not been fully evaluated in infants. Here, we report a 3-month-old female patient with refractory AIHA, who was successfully treated with rituximab. Hemolytic anemia improved rapidly, and there were no severe adverse effects caused by rituximab. After 4.5 months following rituximab treatment, peripheral B cells were gradually reconstituted and required no intravenous immunoglobulin replacement thereafter. The patient has remained disease-free for more than 30 months without any additional treatment. This case suggests that rituximab may be a valuable therapeutic option, given its efficacy and minimal adverse effects in infants with therapy-resistant AIHA.

Mesenchymal chondrosarcoma (MC) is an extremely rare subtype of chondrosarcoma that has a small round-cell sarcoma with focal cartilaginous differentiation, often with a pericytomatous vascular pattern. The non-cartilaginous components are usually dominant, and such lesions might be confused with other small round-cell tumors. Recently, a tumor-specific HEY1-NCOA2 fusion gene was identified in MC. Here we report the case of a 9-year-old boy who was diagnosed with MC by detection of HEY1-NCOA2 fusion signals in almost 50% of tumor cells in tissue sections on fluorescence in situ hybridization (FISH). In this way, the tumor was definitively diagnosed as MC. This case suggests that the detection of the HEY1-NCOA2 fusion gene on FISH is of diagnostic value for MC.

Background Epstein–Barr virus (EBV)-infected T or NK cells cause chronic active EBV infection (CAEBV). Allogeneic hematopoietic stem cell transplantation (HSCT) is curative treatment for CAEBV patients. However, chemotherapy prior to HSCT and optimal conditioning regimen for allogeneic HSCT are still controversial. Patients and Methods We retrospectively analyzed five patients with CAEBV treated with reduced-intensity conditioning (RIC) consisted of fludarabine, cyclophosphamide, and low-dose total-body irradiation followed by allogeneic bone marrow transplantation in a single institute. Only one of five patients received chemotherapy prior to transplantation. We analyzed EBV-infected cells in a patient whose EBV load increased after HSCT by T-cell repertoire assay, separation of T-cell subpopulations, in situ hybridization and microsatellite analysis. Results All five patients achieved engraftment, complete chimera, and eradication of EBV load. All patients have been alive without any serious regimen-related toxicity for more than 16 months following HSCT. However, one patient transplanted from HLA-matched sibling donor developed clonal proliferation of CD4+ Vβ3+ T cells caused by monoclonal EBV infection on day 99 after transplantation. Further analysis revealed that the CD4+ Vβ3+ T cells selectively harbored EBV genome, and these infected cells were derived from donor T cells. Conclusions Allogeneic HSCT with RIC is a safe and effective treatment for better overall survival and less regimen-related toxicity in patients with CAEBV. Our first pediatric case reported in the literature suggests that we should consider the possibility of persistent EBV infection in donor T cells as well as the relapse in recipient cells if EBV load increases after allogeneic HSCT.

Mixed-lineage-leukemia (MLL) fusion oncogenes are intimately involved in acute leukemia and secondary therapy-related acute leukemia. To understand MLL-rearranged leukemia, several murine models for this disease have been established. However, the mouse leukemia derived from mouse hematopoietic stem cells (HSCs) may not be fully comparable with human leukemia. Here we developed a humanized mouse model for human leukemia by transplanting human cord blood-derived HSCs transduced with an MLL-AF10 oncogene into a supra-immunodeficient mouse strain, NOD/Shi-scid, IL-2Rγ(-/-) (NOG) mice. Injection of the MLL-AF10-transduced HSCs into the liver of NOG mice enhanced multilineage hematopoiesis, but did not induce leukemia. Because active mutations in ras genes are often found in MLL-related leukemia, we next transduced the gene for a constitutively active form of K-ras along with the MLL-AF10 oncogene. Eight weeks after transplantation, all the recipient mice had developed acute monoblastic leukemia (the M5 phenotype in French-American-British classification). We thus successfully established a human MLL-rearranged leukemia that was derived in vivo from human HSCs. In addition, since the enforced expression of the mutant K-ras alone was insufficient to induce leukemia, the present model may also be a useful experimental platform for the multi-step leukemogenesis model of human leukemia.