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International audience; PurposeX-linked inhibitor of apoptosis protein (XIAP) deficiency, also known as the X-linked lymphoproliferative syndrome of type 2 (XLP-2), is a rare immunodeficiency characterized by recurrent hemophagocytic lymphohistiocytosis, splenomegaly, and inflammatory bowel disease. Variants in XIAP including missense, non-sense, frameshift, and deletions of coding exons have been reported to cause XIAP deficiency. We studied three young boys with immunodeficiency displaying XLP-2-like clinical features. No genetic variation in the coding exons of XIAP was identified by whole-exome sequencing (WES), although the patients exhibited a complete loss of XIAP expression.MethodsTargeted next-generation sequencing (NGS) of the entire locus of XIAP was performed on DNA samples from the three patients. Molecular investigations were assessed by gene reporter expression assays in HEK cells and CRISPR-Cas9 genome editing in primary T cells.ResultsNGS of XIAP identified three distinct non-coding deletions in the patients that were predicted to be driven by repetitive DNA sequences. These deletions share a common region of 839 bp that encompassed the first non-coding exon of XIAP and contained regulatory elements and marks specific of an active promoter. Moreover, we showed that among the 839 bp, the exon was transcriptionally active. Finally, deletion of the exon by CRISPR-Cas9 in primary cells reduced XIAP protein expression.ConclusionsThese results identify a key promoter sequence contained in the first non-coding exon of XIAP. Importantly, this study highlights that sequencing of the non-coding exons that are not currently captured by WES should be considered in the genetic diagnosis when no variation is found in coding exons.

Background Autosomal recessive (AR) complete IRF8 deficiency is a rare severe inborn error of immunity underlying an absence of blood myeloid mononuclear cells, intracerebral calcifications, and multiple infections. Only three unrelated patients have been reported. Materials and Methods We studied an Argentinian child with multiple infectious diseases and severe pulmonary alveolar proteinosis (PAP). We performed whole-exome sequencing (WES) and characterized his condition by genetic, immunological, and clinical means. Results The patient was born and lived in Argentina. He had a history of viral pulmonary diseases, disseminated disease due to bacillus Calmette-Guérin (BCG), PAP, and cerebral calcifications. He died at the age of 10 months from refractory PAP. WES identified two compound heterozygous variants in IRF8: c.55del and p.R111*. In an overexpression system, the p.R111* cDNA was loss-of-expression, whereas the c.55del cDNA yielded a protein with a slightly lower molecular weight than the wild-type protein. The mutagenesis of methionine residues downstream from c.55del revealed a re-initiation of translation. However, both variants were loss-of-function in a luciferase assay, suggesting that the patient had AR complete IRF8 deficiency. The patient had no blood monocytes or dendritic cells, associated with neutrophilia, and normal counts of NK and other lymphoid cell subsets. Conclusion We describe the fourth patient with AR complete IRF8 deficiency. This diagnosis should be considered in children with PAP, which is probably due to the defective development or function of alveolar macrophages.

WHIM syndrome is a primary autosomal dominant immuno deficiency due to CXCR4 mutations characterized by mucocutaneous warts, hypogammaglobulinemia, recurrent bacterial infections and myelokathesis. Treatment consists in prophylactic antibiotics, immunoglobulin replacement and granulocyte or granulocyte/monocyte colony stimulating factors. We present the case of a 21 year old woman who showed leukopenia at 10 months of age and one year later multiple infections with hypogammaglobulinemia requiring intravenous immunoglobulin. During follow up she developed chronic neutropenia. A bone marrow aspiration showed increased myeloid series with predominance of immature elements. On the basis of infections, low levels of IgG, IgA, IgM and lymphopenia with absent memory B cells, a diagnosis of common variable immunodeficiency was made. She started intravenous immunoglobulin replacement and prophylactic antibiotics. At age 20, small warts in hands that progressed to forearms, knees, abdomen and face were recorded. CXCR4 gene sequencing was done detecting a heterozygous p.Arg334STOP mutation, confirming WHIM syndrome. This disease is infrequent and difficult to diagnose

Few monogenic causes for severe manifestations of common allergic diseases have been identified. Through next-generation sequencing on a cohort of patients with severe atopic dermatitis with and without comorbid infections, we found eight individuals, from four families, with novel heterozygous mutations in CARD11, which encodes a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant CARD11 expression constructs into T cell lines demonstrated both loss-of-function and dominant-interfering activity upon antigen receptor-induced activation of nuclear factor-κB and mammalian target of rapamycin complex 1 (mTORC1). Patient T cells had similar defects, as well as low production of the cytokine interferon-γ (IFN-γ). The mTORC1 and IFN-γ production defects were partially rescued by supplementation with glutamine, which requires CARD11 for import into T cells. Our findings indicate that a single hypomorphic mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis.

In this study, the influence of food availability on the gonadal development of the smooth clam Callista chione was analyzed for the first time. Callista chione adults were maintained for 60 days under controlled conditions with two different diet rations: a scarce diet (3% of dry weight of algae by meat dry weight per day) and a high diet (6%). The condition index, gonadal stage, and oocyte size were measured throughout the experiment. Maturation of gonad was achieved in both groups. Nevertheless, the condition index and oocyte diameter were significantly less in the scarce-diet group. These low values seem to be related to a loss in reserve tissue, not to the release of gametes. Thus, in food-limited conditions, the animals use the energy to mature instead of grow. Comparisons with animals from the field were made during all the study periods, and differences were found. In fact, these individuals were primarily in the postspawning stage, and the oocyte size was considerably smaller, coinciding...

INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease with major diagnostic and therapeutic difficulties, basically comprising two different conditions: primary and secondary forms. Recent advances regarding molecular diagnosis may be useful to distinguish from one another, especially in sporadic cases starting in early infancy. MATERIALS AND METHODS: In this report, we evaluated three Argentinean patients with clinical suspicion of HLH, but without family history. We excluded mutations in the perforin gene but identified in the three patients a novel homozygous deletion (c. 581_584delTGCC; p.Leu194-ProfsX2) in the gene-encoding syntaxin 11 (STX11), causing a premature termination codon. RESULTS AND CONCLUSION: Each parent from the three unrelated families resulted heterozygous for this deletion confirming the diagnosis of familial hemophagocytic lymphohistiocytosis type 4. Patients shared the same single-nucleotide polymorphism profile in STX11 gene, and genotyping at ten microsatellites surrounding this gene support the presence of a single-haplotype block carrying the novel mutation.

Argentina has a large number of patients with definite diagnosis of X-linked agammaglobulinemia reported in the Latin-American registry. Forty-nine of them were seen in our referral pediatric hospital, between 1987 and 2005.A retrospective study of clinical, laboratory, and molecular data showed that respiratory tract infections were the most frequent initial clinical presentation and the most common among all manifestations prior to diagnosis (69%). Up to diagnosis, we found a high frequency of severe infections (sepsis, 14% and meningitis, 16%) and a high proportion of patients with chronic lung disease. During follow-up, the development of chronic lung disease was significantly related with age at diagnosis and inappropriate treatment.Although molecular diagnosis has been available in our center for the past 10 years, there is no doubt that awareness for early recognition of immunodeficiency should be improved through broader and more comprehensive education programs emphasizing characteristics of patients with immunodeficiencies.

Few monogenic causes for severe manifestations of common allergic diseases have been identified. Via next generation sequencing on a cohort of patients with severe atopic dermatitis, some with comorbid infections, we found 8 individuals from 4 families with novel heterozygous mutations in CARD11, a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant expression constructs into T cell lines demonstrated both loss of function and dominant interfering activity upon antigen receptor-induced NF-κB and mTORC1 activation. Patient T-cells had similar defects, as well as diminished IFN-γ cytokine production. The mTORC1 and IFN-γ production defects could be partially rescued by supplementing with glutamine, which requires CARD11 for import into T cells. Our findings indicate a single hypomorphic gene mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis.

Monogenic causes for serious manifestations of common allergic disease inform our mechanistic understanding of the pathogenesis of atopy. However, infections and other syndromic phenotypes often accompany such disorders. We performed next-generation sequencing on a cohort of patients with severe atopic dermatitis with evidence of familial inheritance, regardless of comorbidities. We discovered 9 individuals from 5 families harboring distinct, novel heterozygous mutations in CARD11, a lymphocyte scaffolding protein that facilitates NF-κB and mTOR signaling following antigen receptor (AgR) engagement. Significant infections beyond the skin, and non-immunologic comorbidities, were documented in some but not all patients. Improvement of skin and infectious history were noted in the majority of the patients. Each CARD11 mutant exhibited attenuated AgR-driven signaling to NF-κB and mTORC1, and dominantly interfered with the ability of WT CARD11 to activate these pathways in transfected T cell lines. Primary patient T cells also showed defects in AgR-induced activation of NF-κB and mTORC1, which is critical for promoting Th1 and preventing Th2 responses. Impaired proliferation, mTORC1 signaling and IFN-γ production were partially rescued by supplementing with excess glutamine, which requires CARD11 for import into T cells. In contrast to B cell lymphoproliferative disease associated with gain-of-function CARD11 mutations, and severe combined immunodeficiency associated with null CARD11 mutations, our new findings indicate single hypomorphic mutations in CARD11 can cause potentially correctable cellular defects that lead to severe atopy.