RESUMO
FMS-related tyrosine kinase 3 ligand (FLT3L), encoded by FLT3LG, is a hematopoietic factor essential for the development of natural killer (NK) cells, B cells, and dendritic cells (DCs) in mice. We describe three humans homozygous for a loss-of-function FLT3LG variant with a history of various recurrent infections, including severe cutaneous warts. The patients' bone marrow (BM) was hypoplastic, with low levels of hematopoietic progenitors, particularly myeloid and B cell precursors. Counts of B cells, monocytes, and DCs were low in the patients' blood, whereas the other blood subsets, including NK cells, were affected only moderately, if at all. The patients had normal counts of Langerhans cells (LCs) and dermal macrophages in the skin but lacked dermal DCs. Thus, FLT3L is required for B cell and DC development in mice and humans. However, unlike its murine counterpart, human FLT3L is required for the development of monocytes but not NK cells.
Assuntos
Células Matadoras Naturais , Proteínas de Membrana , Animais , Feminino , Humanos , Masculino , Camundongos , Linfócitos B/metabolismo , Linfócitos B/citologia , Medula Óssea/metabolismo , Linhagem da Célula , Células Dendríticas/metabolismo , Hematopoese , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/citologia , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/imunologia , Células de Langerhans/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Monócitos/metabolismo , Pele/metabolismo , Camundongos Endogâmicos C57BLRESUMO
The molecular basis of the incomplete penetrance of monogenic disorders is unclear. We describe here eight related individuals with autosomal recessive TIRAP deficiency. Life-threatening staphylococcal disease occurred during childhood in the proband, but not in the other seven homozygotes. Responses to all Toll-like receptor 1/2 (TLR1/2), TLR2/6, and TLR4 agonists were impaired in the fibroblasts and leukocytes of all TIRAP-deficient individuals. However, the whole-blood response to the TLR2/6 agonist staphylococcal lipoteichoic acid (LTA) was abolished only in the index case individual, the only family member lacking LTA-specific antibodies (Abs). This defective response was reversed in the patient, but not in interleukin-1 receptor-associated kinase 4 (IRAK-4)-deficient individuals, by anti-LTA monoclonal antibody (mAb). Anti-LTA mAb also rescued the macrophage response in mice lacking TIRAP, but not TLR2 or MyD88. Thus, acquired anti-LTA Abs rescue TLR2-dependent immunity to staphylococcal LTA in individuals with inherited TIRAP deficiency, accounting for incomplete penetrance. Combined TIRAP and anti-LTA Ab deficiencies underlie staphylococcal disease in this patient.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Lipopolissacarídeos/metabolismo , Glicoproteínas de Membrana/deficiência , Receptores de Interleucina-1/deficiência , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/imunologia , Ácidos Teicoicos/metabolismo , Imunidade Adaptativa , Criança , Feminino , Fibroblastos/metabolismo , Humanos , Imunidade Inata , Lipopolissacarídeos/imunologia , Macrófagos/imunologia , Masculino , Glicoproteínas de Membrana/análise , Glicoproteínas de Membrana/genética , Monócitos/metabolismo , Fator 88 de Diferenciação Mieloide/metabolismo , Linhagem , Fagócitos/metabolismo , Mutação Puntual , Isoformas de Proteínas/análise , Isoformas de Proteínas/genética , Receptores de Interleucina-1/análise , Receptores de Interleucina-1/genética , Infecções Estafilocócicas/tratamento farmacológico , Ácidos Teicoicos/imunologia , Receptor 2 Toll-Like/metabolismo , Receptores Toll-Like/agonistas , Receptores Toll-Like/metabolismoRESUMO
B cells and their secreted antibodies are fundamental for host-defense against pathogens. The generation of high-affinity class switched antibodies results from both somatic hypermutation (SHM) of the immunoglobulin (Ig) variable region genes of the B-cell receptor and class switch recombination (CSR) which alters the Ig heavy chain constant region. Both of these processes are initiated by the enzyme activation-induced cytidine deaminase (AID), encoded by AICDA. Deleterious variants in AICDA are causal of hyper-IgM syndrome type 2 (HIGM2), a B-cell intrinsic primary immunodeficiency characterised by recurrent infections and low serum IgG and IgA levels. Biallelic variants affecting exons 2, 3 or 4 of AICDA have been identified that impair both CSR and SHM in patients with autosomal recessive HIGM2. Interestingly, B cells from patients with autosomal dominant HIGM2, caused by heterozygous variants (V186X, R190X) located in AICDA exon 5 encoding the nuclear export signal (NES) domain, show abolished CSR but variable SHM. We herein report the immunological and functional phenotype of two related patients presenting with common variable immunodeficiency who were found to have a novel heterozygous variant in AICDA (L189X). This variant led to a truncated AID protein lacking the last 10 amino acids of the NES at the C-terminal domain. Interestingly, patients' B cells carrying the L189X variant exhibited not only greatly impaired CSR but also SHM in vivo, as well as CSR and production of IgG and IgA in vitro. Our findings demonstrate that the NES domain of AID can be essential for SHM, as well as for CSR, thereby refining the correlation between AICDA genotype and SHM phenotype as well as broadening our understanding of the pathophysiology of HIGM disorders.
Assuntos
Citidina Desaminase , Síndrome de Imunodeficiência com Hiper-IgM , Switching de Imunoglobulina , Humanos , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Síndrome de Imunodeficiência com Hiper-IgM/genética , Imunoglobulina A/genética , Switching de Imunoglobulina/genética , Imunoglobulina G/genética , Fenótipo , Hipermutação Somática de ImunoglobulinaRESUMO
Hematopoietic stem cells (HSCs) are the progenitor cells that give rise to the diverse repertoire of all immune cells. As they differentiate, HSCs yield a series of cell states that undergo gradual commitment to become mature blood cells. Studies of hematopoiesis in murine models have provided critical insights about the lineage relationships among stem cells, progenitors, and mature cells, and these have guided investigations of the molecular basis for these distinct developmental stages. Primary immune deficiencies are caused by inborn errors of immunity that result in immune dysfunction and subsequent susceptibility to severe and recurrent infection(s). Over the last decade there has been a dramatic increase in the number and depth of the molecular, cellular, and clinical characterization of such genetically defined causes of immune dysfunction. Patients harboring inborn errors of immunity thus represent a unique resource to improve our understanding of the multilayered and complex mechanisms underlying lymphocyte development in humans. These breakthrough discoveries not only enable significant advances in the diagnosis of such rare and complex conditions but also provide substantial improvement in the development of personalized treatments. Here, we will discuss the clinical, cellular, and molecular phenotypes, and treatments of selected inborn errors of immunity that impede, either intrinsically or extrinsically, the development of B- or T-cells at different stages.
Assuntos
Regulação da Expressão Gênica/imunologia , Células-Tronco Hematopoéticas/imunologia , Linfopoese/imunologia , Medicina de Precisão/métodos , Doenças da Imunodeficiência Primária/genética , Animais , Diferenciação Celular , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/imunologia , Terapia Genética/métodos , Hematopoese/genética , Hematopoese/imunologia , Células-Tronco Hematopoéticas/citologia , Humanos , Fator de Transcrição Ikaros/genética , Fator de Transcrição Ikaros/imunologia , Janus Quinase 3/genética , Janus Quinase 3/imunologia , Linfócitos/imunologia , Linfócitos/patologia , Linfopoese/genética , Camundongos , Fatores de Transcrição Box Pareados/genética , Fatores de Transcrição Box Pareados/imunologia , Doenças da Imunodeficiência Primária/patologia , Doenças da Imunodeficiência Primária/terapiaRESUMO
Most members of the Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) families transduce signals via a canonical pathway involving the MyD88 adapter and the interleukin-1 receptor-associated kinase (IRAK) complex. This complex contains four molecules, including at least two (IRAK-1 and IRAK-4) active kinases. In mice and humans, deficiencies of IRAK-4 or MyD88 abolish most TLR (except for TLR3 and some TLR4) and IL-1R signaling in both leukocytes and fibroblasts. TLR and IL-1R responses are weak but not abolished in mice lacking IRAK-1, whereas the role of IRAK-1 in humans remains unclear. We describe here a boy with X-linked MECP2 deficiency-related syndrome due to a large de novo Xq28 chromosomal deletion encompassing both MECP2 and IRAK1 Like many boys with MECP2 null mutations, this child died very early, at the age of 7 mo. Unlike most IRAK-4- or MyD88-deficient patients, he did not suffer from invasive bacterial diseases during his short life. The IRAK-1 protein was completely absent from the patient's fibroblasts, which responded very poorly to all TLR2/6 (PAM2CSK4, LTA, FSL-1), TLR1/2 (PAM3CSK4), and TLR4 (LPS, MPLA) agonists tested but had almost unimpaired responses to IL-1ß. By contrast, the patient's peripheral blood mononuclear cells responded normally to all TLR1/2, TLR2/6, TLR4, TLR7, and TLR8 (R848) agonists tested, and to IL-1ß. The death of this child precluded long-term evaluations of the clinical consequences of inherited IRAK-1 deficiency. However, these findings suggest that human IRAK-1 is essential downstream from TLRs but not IL-1Rs in fibroblasts, whereas it plays a redundant role downstream from both TLRs and IL-1Rs in leukocytes.
Assuntos
Fibroblastos/metabolismo , Quinases Associadas a Receptores de Interleucina-1/deficiência , Receptores Toll-Like/metabolismo , Deleção Cromossômica , Cromossomos Humanos X/genética , Humanos , Lactente , Quinases Associadas a Receptores de Interleucina-1/genética , Leucócitos/metabolismo , Masculino , Proteína 2 de Ligação a Metil-CpG/genética , Receptores de Interleucina-1/metabolismo , Transdução de Sinais , Receptores Toll-Like/genéticaRESUMO
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.
Assuntos
Infecções Bacterianas/imunologia , Candidíase/imunologia , Micoses/imunologia , Receptores de Interleucina-17/deficiência , Receptores de Interleucina-17/genética , Alelos , Candida , Membrana Celular , Criança , Pré-Escolar , Saúde da Família , Feminino , Fibroblastos/metabolismo , Genes Recessivos , Estudo de Associação Genômica Ampla , Células HEK293 , Homozigoto , Humanos , Imunofenotipagem , Lactente , Recém-Nascido , Interleucina-17/metabolismo , Masculino , Mutação , Fases de Leitura Aberta , Linhagem , Receptores de Interleucina-17/metabolismo , Pele/microbiologia , Linfócitos T/citologiaRESUMO
The diagnosis of VACTERL syndrome can be elusive, especially in the prenatal life, due to the presence of malformations that overlap those present in other genetic conditions, including the Fanconi anemia (FA). We report on three VACTERL cases within two families, where the two who arrived to be born died shortly after birth due to severe organs' malformations. The suspicion of VACTERL association was based on prenatal ultrasound assessment and postnatal features. Subsequent chromosome breakage analysis suggested the diagnosis of FA. Finally, by next-generation sequencing based on the analysis of the exome in one family and of a panel of Fanconi genes in the second one, we identified novel FANCL truncating mutations in both families. We used ectopic expression of wild-type FANCL to functionally correct the cellular FA phenotype for both mutations. Our study emphasizes that the diagnosis of FA should be considered when VACTERL association is suspected. Furthermore, we show that loss-of-function mutations in FANCL result in a severe clinical phenotype characterized by early postnatal death.
Assuntos
Canal Anal/anormalidades , Esôfago/anormalidades , Proteína do Grupo de Complementação L da Anemia de Fanconi/genética , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/genética , Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/genética , Rim/anormalidades , Deformidades Congênitas dos Membros/diagnóstico , Deformidades Congênitas dos Membros/genética , Mutação , Fenótipo , Coluna Vertebral/anormalidades , Traqueia/anormalidades , Aborto Induzido , Quebra Cromossômica , Diagnóstico Diferencial , Exoma , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Recém-Nascido , Nascido Vivo , Masculino , Gravidez , Diagnóstico Pré-Natal , Índice de Gravidade de DoençaRESUMO
BACKGROUND: SOX9 is a widely expressed transcription factor playing several relevant functions during development and essential for testes differentiation. It is considered to be the direct target gene of the protein encoded by SRY and its overexpression in an XX murine gonad can lead to male development in the absence of Sry. Recently, a family was reported with a 178 kb duplication in the gene desert region ending about 500 kb upstream of SOX9 in which 46,XY duplicated persons were completely normal and fertile whereas the 46,XX ones were males who came to clinical attention because of infertility. METHODS AND RESULTS: We report a family with two azoospermic brothers, both 46,XX, SRY negative, having a 96 kb triplication 500 kb upstream of SOX9. Both subjects have been analyzed trough oligonucleotide array-CGH and the triplication was confirmed and characterised through qPCR, defining the minimal region of amplification upstream of SOX9 associated with 46,XX infertile males, SRY negative. CONCLUSIONS: Our results confirm that even in absence of SRY, complete male differentiation may occur, possibly driven by overexpression of SOX9 in the gonadal ridge, as a consequence of the amplification of a gene desert region. We hypothesize that this region contains gonadal specific long-range regulation elements whose alteration may impair the normal sex development. Our data show that normal XX males, with alteration in copy number or, possibly, in the critical sequence upstream to SOX9 are a new category of infertility inherited in a dominant way with expression limited to the XX background.
Assuntos
Azoospermia/genética , Genes sry , Fatores de Transcrição SOX9/genética , Transtornos dos Cromossomos Sexuais/genética , Mapeamento Cromossômico , Hibridização Genômica Comparativa , Feminino , Duplicação Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Reação em Cadeia da Polimerase em Tempo Real , Aberrações dos Cromossomos SexuaisRESUMO
Cognitive, emotional, and behavioral characterizations have been reported for patients with a few chromosomal imbalances, but not for patients with a 13q deletion. We report the neuropsychological profile and specific linguistic, visual, spatial, constructional, and behavioral disabilities of a young man with a de novo chromosome 13 deletion (13)(q21.32)(q31.1). Karyotyping at 550 G-band resolution showed that the patient's parents did not share the deletion. According to array-comparative genomic hybridization, the deletion spanned about 14 Mb and included 27 genes. A fluorescence in situ hybridization assay revealed an intact 13q telomere on the partially deleted chromosome. The patient had multiple morphologic and ophthalmologic anomalies. A brain magnetic resonance imaging study did not show gross brain defects. Neuropsychological testing showed an acceptable use of everyday language, but mild mental retardation, executive dysfunction, and very poor performance on visual, visuospatial, and constructional tasks. Establishing a neuropsychological profile for a patient with a specific genetic defect can help clinicians, parents, and teachers work to meet the patient's medical, academic, and behavioral needs.
Assuntos
Deleção Cromossômica , Transtornos Cromossômicos/psicologia , Cromossomos Humanos Par 13 , Transtornos Cognitivos/genética , Deficiência Intelectual/genética , Percepção Espacial , Transtornos Cromossômicos/genética , Transtornos Cognitivos/psicologia , Função Executiva , Humanos , Deficiência Intelectual/psicologia , Idioma , Masculino , Testes NeuropsicológicosRESUMO
With the advent of next-generation sequencing (NGS), monogenic forms of common variable immunodeficiency (CVID) have been increasingly described. Our study aimed to identify disease-causing variants in a Western Australian CVID cohort using a novel targeted NGS panel. Targeted amplicon NGS was performed on 22 unrelated subjects who met the formal European Society for Immunodeficiencies-Pan-American Group for Immunodeficiency diagnostic criteria for CVID and had at least one of the following additional criteria: disease onset at age <18 years, autoimmunity, low memory B lymphocytes, family history, and/or history of lymphoproliferation. Candidate variants were assessed by in silico predictions of deleteriousness, comparison to the literature, and classified according to the American College of Medical Genetics and Genomics-Association for Molecular Pathology criteria. All detected genetic variants were verified independently by an external laboratory, and additional functional studies were performed if required. Pathogenic or likely pathogenic variants were detected in 6 of 22 (27%) patients. Monoallelic variants of uncertain significance were also identified in a further 4 of 22 patients (18%). Pathogenic variants, likely pathogenic variants, or variants of uncertain significance were found in TNFRSF13B, TNFRSF13C, ICOS, AICDA, IL21R, NFKB2, and CD40LG, including novel variants and variants with unexpected inheritance pattern. Targeted amplicon NGS is an effective tool to identify monogenic disease-causing variants in CVID, and is comparable or superior to other NGS methods. Moreover, targeted amplicon NGS identified patients who may benefit from targeted therapeutic strategies and had important implications for family members.
Assuntos
Imunodeficiência de Variável Comum , Adolescente , Austrália , Estudos de Coortes , Imunodeficiência de Variável Comum/diagnóstico , Imunodeficiência de Variável Comum/genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , MutaçãoRESUMO
Rare intrachromosomal triplications producing partial tetrasomies have been reported for a number of chromosomes. A detailed molecular characterization, necessary to define the mechanism of their formation, has so far been lacking. We report on the detailed clinical, cytogenetic, and molecular characterization of two triplications, one de novo involving chromosome 18q, the other familial on chromosome Xp. The clinical phenotype of the patient with 18q triplication, very likely due to overexpression of one or more of the genes in the region, consists mainly of facial dysmorphisms and developmental delay. The familial Xp triplication does not cause an increase in the number of copies of any gene and is almost certainly a polymorphism. The rearrangements are actually complex duplications/triplications. In both patients, their proximal breakpoints are located within complex segmental duplications, one containing the VCX gene cluster on chromosome Xp, the other the TCEB3 genes on chromosome 18q. A proximal duplicated region is also present in both patients. All junctions we analyzed were formed by non-homologous end joining (NHEJ). The structural features shared between our patients suggest the involvement of a common mechanism in the genesis of interstitial intrachromosomal triplications.
Assuntos
Cromossomos Humanos X/genética , Deficiências do Desenvolvimento/genética , Trissomia/genética , Sequência de Bases , Criança , Pré-Escolar , Aberrações Cromossômicas , Pontos de Quebra do Cromossomo , Cromossomos Humanos Par 18/genética , Clonagem Molecular , Reparo do DNA por Junção de Extremidades , Deficiências do Desenvolvimento/patologia , Elonguina , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Heterogeneidade Genética , Humanos , Hibridização in Situ Fluorescente , Lactente , Recém-Nascido , Masculino , Metáfase , Dados de Sequência Molecular , Proteínas Nucleares/genética , Fenótipo , Fatores de Transcrição/genéticaRESUMO
Mitochondrial DNA (mtDNA) has been suggested to drive immune system activation, but the induction of interferon signaling by mtDNA has not been demonstrated in a Mendelian mitochondrial disease. We initially ascertained two patients, one with a purely neurological phenotype and one with features suggestive of systemic sclerosis in a syndromic context, and found them both to demonstrate enhanced interferon-stimulated gene (ISG) expression in blood. We determined each to harbor a previously described de novo dominant-negative heterozygous mutation in ATAD3A, encoding ATPase family AAA domain-containing protein 3A (ATAD3A). We identified five further patients with mutations in ATAD3A and recorded up-regulated ISG expression and interferon α protein in four of them. Knockdown of ATAD3A in THP-1 cells resulted in increased interferon signaling, mediated by cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING). Enhanced interferon signaling was abrogated in THP-1 cells and patient fibroblasts depleted of mtDNA. Thus, mutations in the mitochondrial membrane protein ATAD3A define a novel type I interferonopathy.
Assuntos
ATPases Associadas a Diversas Atividades Celulares/genética , Interferons/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/genética , Mutação , Nucleotidiltransferases/metabolismo , ATPases Associadas a Diversas Atividades Celulares/metabolismo , Criança , Pré-Escolar , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Feminino , Genes Dominantes , Humanos , Interferons/genética , Masculino , Proteínas Mitocondriais/metabolismo , Nucleotidiltransferases/genética , Escleroderma Sistêmico/genética , Escleroderma Sistêmico/patologia , Transdução de Sinais , Células THP-1 , Adulto JovemRESUMO
The Peutz-Jeghers Syndrome (PJS) is an autosomal dominant polyposis disorder with increased risk of multiple cancers. STK11/LKB1 (hereafter named STK11) germline mutations account for the large majority of PJS cases whereas large deletions account for about 30% of the cases. We report here the first thorough molecular characterization of 15 large deletions identified in a cohort of 51 clinically well-characterized PJS patients. The deletions were identified by MLPA analysis and characterized by custom CGH-array and quantitative PCR to define their boundaries. The deletions, ranging from 2.9 to 180 kb, removed one or more loci contiguous to the STK11 gene in six patients, while partial STK11 gene deletions were present in the remaining nine cases. By means of DNA sequencing, we were able to precisely characterize the breakpoints in each case. Of the 30 breakpoints, 16 were located in Alu elements, revealing non-allelic homologous recombination (NAHR) as the putative mechanism for the deletions of the STK11 gene, which lays in a region with high Alu density. In the remaining cases, other mechanisms could be hypothesized, such as microhomology-mediated end-joining (MMEJ) or non-homologous end-joining (NHEJ). In conclusion we here demonstrated the non-random occurrence of large deletions associated with PJS. All our patients had a classical PJS phenotype, which shows that haploinsufficiency for SBNO2, C19orf26, ATP5D, MIDN, C19orf23, CIRBP, C19orf24,and EFNA2, does not apparently affect their clinical phenotype.
Assuntos
Deleção Cromossômica , Deleção de Genes , Síndrome de Peutz-Jeghers/genética , Proteínas Serina-Treonina Quinases/genética , Quinases Proteína-Quinases Ativadas por AMP , Adolescente , Adulto , Elementos Alu/genética , Criança , Pré-Escolar , Quebra Cromossômica , Cromossomos Humanos Par 19/genética , Análise Mutacional de DNA , Feminino , Mutação em Linhagem Germinativa , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Técnicas de Amplificação de Ácido Nucleico/métodos , Síndrome de Peutz-Jeghers/patologia , Reação em Cadeia da Polimerase , Adulto JovemRESUMO
Inappropriate stimulation or defective negative regulation of the type I interferon response can lead to autoinflammation. In genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome, we identified biallelic mutations in LSM11 and RNU7-1, which encode components of the replication-dependent histone pre-mRNA-processing complex. Mutations were associated with the misprocessing of canonical histone transcripts and a disturbance of linker histone stoichiometry. Additionally, we observed an altered distribution of nuclear cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) and enhanced interferon signaling mediated by the cGAS-stimulator of interferon genes (STING) pathway in patient-derived fibroblasts. Finally, we established that chromatin without linker histone stimulates cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) production in vitro more efficiently. We conclude that nuclear histones, as key constituents of chromatin, are essential in suppressing the immunogenicity of self-DNA.
Assuntos
Cromatina/metabolismo , Histonas/metabolismo , Interferon Tipo I/biossíntese , Precursores de RNA/metabolismo , Proteínas de Ligação a RNA/genética , Ribonucleoproteína Nuclear Pequena U7/genética , Doenças Autoimunes do Sistema Nervoso/genética , Doenças Autoimunes do Sistema Nervoso/imunologia , Linhagem Celular , DNA/imunologia , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/imunologia , Células HCT116 , Células HEK293 , Doenças Hereditárias Autoinflamatórias/genética , Doenças Hereditárias Autoinflamatórias/imunologia , Humanos , Proteínas de Membrana/metabolismo , Malformações do Sistema Nervoso/genética , Malformações do Sistema Nervoso/imunologia , Nucleotídeos Cíclicos/biossíntese , Nucleotidiltransferases/metabolismoRESUMO
Most humans are exposed to Tropheryma whipplei (Tw). Whipple's disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing four WD patients and five healthy Tw chronic carriers. We hypothesized that WD displays autosomal dominant (AD) inheritance, with age-dependent incomplete penetrance. We identified a single very rare non-synonymous mutation in the four patients: the private R98W variant of IRF4, a transcription factor involved in immunity. The five Tw carriers were younger, and also heterozygous for R98W. We found that R98W was loss-of-function, modified the transcriptome of heterozygous leukocytes following Tw stimulation, and was not dominant-negative. We also found that only six of the other 153 known non-synonymous IRF4 variants were loss-of-function. Finally, we found that IRF4 had evolved under purifying selection. AD IRF4 deficiency can underlie WD by haploinsufficiency, with age-dependent incomplete penetrance.
Assuntos
Haploinsuficiência/genética , Fatores Reguladores de Interferon/genética , Tropheryma/genética , Doença de Whipple/genética , Idoso , Idoso de 80 Anos ou mais , Feminino , Predisposição Genética para Doença/genética , Humanos , Leucócitos/microbiologia , Masculino , Pessoa de Meia-Idade , Mutação , Linhagem , Penetrância , Tropheryma/patogenicidade , Doença de Whipple/microbiologia , Doença de Whipple/patologiaRESUMO
Microbial nucleic acid recognition serves as the major stimulus to an antiviral response, implying a requirement to limit the misrepresentation of self nucleic acids as non-self and the induction of autoinflammation. By systematic screening using a panel of interferon-stimulated genes we identify two siblings and a singleton variably demonstrating severe neonatal anemia, membranoproliferative glomerulonephritis, liver fibrosis, deforming arthropathy and increased anti-DNA antibodies. In both families we identify biallelic mutations in DNASE2, associated with a loss of DNase II endonuclease activity. We record increased interferon alpha protein levels using digital ELISA, enhanced interferon signaling by RNA-Seq analysis and constitutive upregulation of phosphorylated STAT1 and STAT3 in patient lymphocytes and monocytes. A hematological disease transcriptomic signature and increased numbers of erythroblasts are recorded in patient peripheral blood, suggesting that interferon might have a particular effect on hematopoiesis. These data define a type I interferonopathy due to DNase II deficiency in humans.
Assuntos
Desoxirribonucleases/deficiência , Endodesoxirribonucleases/deficiência , Doenças Hereditárias Autoinflamatórias/enzimologia , Interferon-alfa/imunologia , Transdução de Sinais/imunologia , Adolescente , Antivirais/farmacologia , Criança , Desoxirribonucleases/genética , Desoxirribonucleases/imunologia , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/imunologia , Eritroblastos/imunologia , Feminino , Perfilação da Expressão Gênica , Hematopoese/imunologia , Doenças Hereditárias Autoinflamatórias/sangue , Doenças Hereditárias Autoinflamatórias/genética , Doenças Hereditárias Autoinflamatórias/imunologia , Humanos , Interferon-alfa/sangue , Interferon-alfa/metabolismo , Masculino , Mutação , Fosforilação , RNA Mensageiro/análise , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/metabolismo , Análise de Sequência de RNA , Regulação para Cima/efeitos dos fármacosRESUMO
We analyzed by next-generation sequencing (NGS) 67 epilepsy genes in 19 patients with different types of either isolated or syndromic epileptic disorders and in 15 controls to investigate whether a quick and cheap molecular diagnosis could be provided. The average number of nonsynonymous and splice site mutations per subject was similar in the two cohorts indicating that, even with relatively small targeted platforms, finding the disease gene is not an univocal process. Our diagnostic yield was 47% with nine cases in which we identified a very likely causative mutation. In most of them no interpretation would have been possible in absence of detailed phenotype and familial information. Seven out of 19 patients had a phenotype suggesting the involvement of a specific gene. Disease-causing mutations were found in six of these cases. Among the remaining patients, we could find a probably causative mutation only in three. None of the genes affected in the latter cases had been suspected a priori. Our protocol requires 8-10 weeks including the investigation of the parents with a cost per patient comparable to sequencing of 1-2 medium-to-large-sized genes by conventional techniques. The platform we used, although providing much less information than whole-exome or whole-genome sequencing, has the advantage that can also be run on 'benchtop' sequencers combining rapid turnaround times with higher manageability.
Assuntos
Epilepsia/diagnóstico , Epilepsia/genética , Testes Genéticos , Sequenciamento de Nucleotídeos em Larga Escala , Adolescente , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Biologia Computacional , Feminino , Seguimentos , Estudos de Associação Genética , Humanos , Lactente , Masculino , Mutação , Fluxo de Trabalho , Adulto JovemRESUMO
OBJECTIVE: To investigate the molecular defect underlying a large Italian kindred with progressive adult-onset respiratory failure, proximal weakness of the upper limbs, and evidence of lower motor neuron degeneration. METHODS: We describe the clinical features of 5 patients presenting with prominent respiratory insufficiency, proximal weakness of the upper limbs, and no signs of frontotemporal lobar degeneration or semantic dementia. Molecular analysis was performed combining linkage and exome sequencing analyses. Further investigations included transcript analysis and immunocytochemical and protein studies on established cell models. RESULTS: Genome-wide linkage analysis showed an association with chromosome 17q21. Exome analysis disclosed a missense change in MAPT segregating dominantly with the disease and resulting in D348G-mutated tau protein. Motor neuron cell lines overexpressing mutated D348G tau isoforms displayed a consistent reduction in neurite length and arborization. The mutation does not seem to modify tau interactions with microtubules. Neuropathologic studies were performed in one affected subject, which exhibited α-motoneuron loss and atrophy of the spinal anterior horns with accumulation of phosphorylated tau within the surviving motor neurons. Staining for 3R- and 4R-tau revealed pathology similar to that observed in familial cases harboring MAPT mutations. CONCLUSION: Our study broadens the phenotype of tauopathies to include lower motor neuron disease and implicate tau degradation pathway defects in motor neuron degeneration.
Assuntos
Doença dos Neurônios Motores/genética , Insuficiência Respiratória/genética , Proteínas tau/genética , Idade de Início , Idoso , Linhagem Celular , Cromossomos Humanos Par 17/genética , Exoma/genética , Feminino , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Doença dos Neurônios Motores/patologia , Doença dos Neurônios Motores/fisiopatologia , Mutação/genética , Linhagem , Fenótipo , Insuficiência Respiratória/patologia , Insuficiência Respiratória/fisiopatologiaRESUMO
We present a patient affected by Dravet syndrome. Thorough analysis of genes that might be involved in the pathogenesis of such phenotype with both conventional and next generation sequencing resulted negative, therefore she was investigated by a-GCH that showed the presence of an unbalanced translocation resulting in a der(4)t(4;8)(p16.3,p23.3). This was an unconventional translocation, different from the recurrent translocation affiliated with WHS and did not involve LETM1.