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1.
RMD Open ; 4(2): e000740, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30402268

RESUMO

Objectives: TNFAIP3 encodes A20 that negatively regulates nuclear factor kappa light chain enhancer of activated B cells (NF-κB), the major transcription factor coordinating inflammatory gene expression. TNFAIP3 polymorphisms have been linked with a spectrum of inflammatory and autoimmune diseases and, recently, loss-of-function mutations in A20 were found to cause a novel inflammatory disease 'haploinsufficiency of A20' (HA20). Here we describe a family with HA20 caused by a novel TNFAIP3 loss-of-function mutation and elucidate the upstream molecular mechanisms linking HA20 to dysregulation of NF-κB and the related inflammasome pathway. Methods: NF-κB activation was studied in a mutation-expressing cell line using luciferase reporter assay. Physical and close-proximity protein-protein interactions of wild-type and TNFAIP3 p.(Lys91*) mutant A20 were analysed using mass spectrometry. NF-κB -dependent transcription, cytokine secretion and inflammasome activation were compared in immune cells of the HA20 patients and control subjects. Results: The protein-protein interactome of p.(Lys91*) mutant A20 was severely impaired, including interactions with proteins regulating NF-κB activation, DNA repair responses and the NLR family pyrin domain containing 3 (NLRP3) inflammasome. The p.(Lys91*) mutant A20 failed to suppress NF-κB signalling, which led to increased NF-κB -dependent proinflammatory cytokine transcription. Functional experiments in the HA20 patients' immune cells uncovered a novel caspase-8-dependent mechanism of NLRP3 inflammasome hyperresponsiveness that mediated the excessive secretion of interleukin-1ß and interleukin-18. Conclusions: The current findings significantly deepen our understanding of the molecular mechanisms underlying HA20 and other diseases associated with reduced A20 expression or function, paving the way for future therapeutic targeting of the pathway.

2.
Orphanet J Rare Dis ; 13(1): 139, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30115091

RESUMO

BACKGROUND: The telomere biology disorders (TBDs) include a range of multisystem diseases characterized by mucocutaneous symptoms and bone marrow failure. In dyskeratosis congenita (DKC), the clinical features of TBDs stem from the depletion of crucial stem cell populations in highly proliferative tissues, resulting from abnormal telomerase function. Due to the wide spectrum of clinical presentations and lack of a conclusive laboratory test it may be challenging to reach a clinical diagnosis, especially if patients lack the pathognomonic clinical features of TBDs. METHODS: Clinical sequencing was performed on a cohort of patients presenting with variable immune phenotypes lacking molecular diagnoses. Hypothesis-free whole-exome sequencing (WES) was selected in the absence of compelling diagnostic hints in patients with variable immunological and haematological conditions. RESULTS: In four patients belonging to three families, we have detected five novel variants in known TBD-causing genes (DKC1, TERT and RTEL1). In addition to the molecular findings, they all presented shortened blood cell telomeres. These findings are consistent with the displayed TBD phenotypes, addressing towards the molecular diagnosis and subsequent clinical follow-up of the patients. CONCLUSIONS: Our results strongly support the utility of WES-based approaches for routine genetic diagnostics of TBD patients with heterogeneous or atypical clinical presentation who otherwise might remain undiagnosed.

4.
J Allergy Clin Immunol ; 140(3): 782-796, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28115215

RESUMO

BACKGROUND: The nuclear factor κ light-chain enhancer of activated B cells (NF-κB) signaling pathway is a key regulator of immune responses. Accordingly, mutations in several NF-κB pathway genes cause immunodeficiency. OBJECTIVE: We sought to identify the cause of disease in 3 unrelated Finnish kindreds with variable symptoms of immunodeficiency and autoinflammation. METHODS: We applied genetic linkage analysis and next-generation sequencing and functional analyses of NFKB1 and its mutated alleles. RESULTS: In all affected subjects we detected novel heterozygous variants in NFKB1, encoding for p50/p105. Symptoms in variant carriers differed depending on the mutation. Patients harboring a p.I553M variant presented with antibody deficiency, infection susceptibility, and multiorgan autoimmunity. Patients with a p.H67R substitution had antibody deficiency and experienced autoinflammatory episodes, including aphthae, gastrointestinal disease, febrile attacks, and small-vessel vasculitis characteristic of Behçet disease. Patients with a p.R157X stop-gain experienced hyperinflammatory responses to surgery and showed enhanced inflammasome activation. In functional analyses the p.R157X variant caused proteasome-dependent degradation of both the truncated and wild-type proteins, leading to a dramatic loss of p50/p105. The p.H67R variant reduced nuclear entry of p50 and showed decreased transcriptional activity in luciferase reporter assays. The p.I553M mutation in turn showed no change in p50 function but exhibited reduced p105 phosphorylation and stability. Affinity purification mass spectrometry also demonstrated that both missense variants led to altered protein-protein interactions. CONCLUSION: Our findings broaden the scope of phenotypes caused by mutations in NFKB1 and suggest that a subset of autoinflammatory diseases, such as Behçet disease, can be caused by rare monogenic variants in genes of the NF-κB pathway.


Assuntos
Doenças Autoimunes/genética , Síndromes de Imunodeficiência/genética , NF-kappa B/genética , Adulto , Idoso , Linhagem Celular , Criança , Feminino , Heterozigoto , Humanos , Inflamação/genética , Leucócitos Mononucleares/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação , Fenótipo
5.
Eur J Hum Genet ; 24(10): 1473-8, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27142677

RESUMO

Antibody class-switch recombination and somatic hypermutation critically depend on the function of activation-induced cytidine deaminase (AID). Rare variants in its gene AICDA have been reported to cause autosomal recessive AID deficiency (autosomal recessive hyper-IgM syndrome type 2 (HIGM2)). Exome sequencing of a multicase Finnish family with an HIGM2 phenotype identified a rare, homozygous, variant (c.416T>C, p.(Met139Thr)) in the AICDA gene, found to be significantly enriched in the Finnish population compared with other populations of European origin (38.56-fold, P<0.001). The population history of Finland, characterized by a restricted number of founders, isolation and several population bottlenecks, has caused enrichment of certain rare disease-causing variants and losses of others, as part of a phenomenon called the Finnish Disease Heritage. Accordingly, rare founder mutations cause the majority of observed Finnish cases in these mostly autosomal recessive disorders that consequently are more frequent in Finland than elsewhere. Screening of all currently known Finnish patients with an HIGM2 phenotype showed them to be homozygous for p.(Met139Thr). All the Finnish p.(Met139Thr) carriers with available data on their geographic descent originated from the eastern and northeastern parts of Finland. They were observed to share more of their genome identity by descent (IBD) than Finns in general (P<0.001), and they all carried a 207.5-kb ancestral haplotype containing the variant. In conclusion, the identified p.(Met139Thr) variant is significantly enriched in Finns and explains all thus far found AID deficiencies in Finland.


Assuntos
Citidina Desaminase/genética , Frequência do Gene , Síndrome de Imunodeficiência com Hiper-IgM/genética , Mutação , Linhagem , Adulto , Criança , Feminino , Finlândia , Efeito Fundador , Haplótipos , Heterozigoto , Homozigoto , Humanos , Síndrome de Imunodeficiência com Hiper-IgM/diagnóstico , Lactente , Masculino
6.
Blood ; 125(4): 639-48, 2015 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-25349174

RESUMO

The signal transducer and activator of transcription (STAT) family of transcription factors orchestrate hematopoietic cell differentiation. Recently, mutations in STAT1, STAT5B, and STAT3 have been linked to development of immunodysregulation polyendocrinopathy enteropathy X-linked-like syndrome. Here, we immunologically characterized 3 patients with de novo activating mutations in the DNA binding or dimerization domains of STAT3 (p.K392R, p.M394T, and p.K658N, respectively). The patients displayed multiorgan autoimmunity, lymphoproliferation, and delayed-onset mycobacterial disease. Immunologically, we noted hypogammaglobulinemia with terminal B-cell maturation arrest, dendritic cell deficiency, peripheral eosinopenia, increased double-negative (CD4(-)CD8(-)) T cells, and decreased natural killer, T helper 17, and regulatory T-cell numbers. Notably, the patient harboring the K392R mutation developed T-cell large granular lymphocytic leukemia at age 14 years. Our results broaden the spectrum of phenotypes caused by activating STAT3 mutations, highlight the role of STAT3 in the development and differentiation of multiple immune cell lineages, and strengthen the link between the STAT family of transcription factors and autoimmunity.


Assuntos
Agamaglobulinemia , Doenças Autoimunes , Doenças Genéticas Inatas , Leucemia Linfocítica Granular Grande , Mutação de Sentido Incorreto , Infecções por Mycobacterium , Fator de Transcrição STAT3 , Adolescente , Adulto , Agamaglobulinemia/genética , Agamaglobulinemia/imunologia , Agamaglobulinemia/patologia , Substituição de Aminoácidos , Doenças Autoimunes/genética , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Linfócitos B/imunologia , Linfócitos B/patologia , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Células Dendríticas/imunologia , Células Dendríticas/patologia , Feminino , Doenças Genéticas Inatas/genética , Doenças Genéticas Inatas/imunologia , Doenças Genéticas Inatas/patologia , Humanos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/patologia , Leucemia Linfocítica Granular Grande/genética , Leucemia Linfocítica Granular Grande/imunologia , Leucemia Linfocítica Granular Grande/patologia , Infecções por Mycobacterium/genética , Infecções por Mycobacterium/imunologia , Infecções por Mycobacterium/patologia , Estrutura Terciária de Proteína , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/patologia , Células Th17/imunologia , Células Th17/patologia
7.
Parkinsonism Relat Disord ; 18(3): 257-62, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22104010

RESUMO

BACKGROUND: Significant efforts have been focused on investigating the contribution of common variants to Parkinson disease (PD) risk. Several independent GWAS and metanalysis studies have shown a genome-wide significant association of single nucleotide polymorphisms (SNPs) in the α-synuclein (SNCA) and microtubule-associated protein tau (MAPT) regions. Here we investigated the role of SNCA and MAPT as PD susceptibility genes in a large Italian population of 904 patients and 891 controls. An evaluation of gene-gene and gene-environment interactions in association with PD was also attempted. METHODS: The SNCA Rep1 microsatellite was genotyped by a fluorescent PCR assay, whereas the SNPlex genotyping system was used to genotype 12 additional markers across the SNCA gene, and 2 SNPs tagging the risk MAPT H1 haplotype. RESULTS: Single-marker analysis demonstrated nominal evidence of association for: i) the 261-bp-long allele of Rep1; ii) 7 SNPs in the SNCA region (top SNP: rs356186, P = 3.08 × 10(-04), intron 4); iii) both SNPs identifying the MAPT H1 haplotype (P = 4.63 × 10(-04) and P = 4.23 × 10(-04) for rs1800547 and rs9468, respectively). Moreover, we found a highly significant protective haplotype spanning ∼83 kb from intron 4 to the 3' end of SNCA (P = 1.29 × 10(-05)). CONCLUSIONS: Our findings strongly confirm SNCA and MAPT as major PD susceptibility genes for idiopathic PD in the Italian population. Interaction analyses did not evidence either epistatic effects between the two loci or gene-environment interactions.


Assuntos
Predisposição Genética para Doença/genética , Doença de Parkinson/genética , alfa-Sinucleína/genética , Proteínas tau/genética , Idoso , Epistasia Genética , Feminino , Interação Gene-Ambiente , Genótipo , Humanos , Itália , Masculino , Repetições de Microssatélites/genética , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único/genética
8.
Int J Audiol ; 50(2): 133-8, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21114417

RESUMO

OBJECTIVE: the aim of this work was to evaluate the possible different impacts of genetic and environmental factors in childhood deafness in northern Cameroon. GJB2 mutations are responsible for more than half of all cases of prelingual nonsyndromic recessive deafness in Caucasians, representing the most important deafness-causing factor in the industrialized world. Other genes such as MTRNR1 are also involved. In sub-Saharan Africa, environmental factors seem to dominate genetic contributions, but few studies on the etiology of deafness in Africa are available for comparison. DESIGN: prospective cross sectional study. STUDY SAMPLE: we performed a molecular screen of the GJB2 and MTRNR1 genes in 70 deaf children and 67 unaffected controls in Maroua (Cameroon) and a literature analysis focused on deafness epidemiology in developing countries. RESULTS: no GJB2 mutations emerged, and only a single MTRNR1 variant that may be pathogenic was found. CONCLUSION: environmental factors turn out to be more relevant than genetic factor in the Maroua population.


Assuntos
Conexinas/genética , Surdez/genética , RNA Ribossômico/genética , Camarões , Criança , Pré-Escolar , Conexina 26 , Estudos Transversais , Feminino , Genes Mitocondriais , Testes Auditivos , Humanos , Masculino , Estudos Prospectivos
9.
Neurobiol Aging ; 32(11): 1994-2005, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20060621

RESUMO

The Grb10-Interacting GYF Protein-2 (GIGYF2) gene has been proposed as the Parkinson-disease (PD) gene underlying the PARK11 locus. However, association of GIGYF2 with PD has been challenged and a functional validation of GIGYF2 mutations is lacking. In this frame, we performed a mutational screening of GIGYF2 in an Italian PD cohort. Exons containing known mutations were analyzed in 552 cases and 552 controls. Thereafter, a subset of 184 familial PD cases and controls were subjected to a full coding-exon screening. These analyses identified 8 missense variations in 9 individuals (4 cases, 5 controls). Furthermore, we developed a zebrafish model of gigyf2 deficiency. Abrogation of gigyf2 function in zebrafish embryos did not lead to a drastic cell loss in diencephalic dopaminergic (DA) neuron clusters, suggesting that gigyf2 is not required for DA neuron differentiation. Notably, gigyf2 functional abrogation did not increase diencephalic DA neurons susceptibility to the PD-inducing drug MPP+. These data, together with those recently reported by other groups, suggest that GIGYF2 is unlikely to be the PARK11 gene.


Assuntos
Proteínas de Transporte/genética , Predisposição Genética para Doença , Doença de Parkinson/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Estudos de Casos e Controles , Clonagem de Organismos , Análise Mutacional de DNA , Feminino , Variação Genética , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Peixe-Zebra
10.
Parkinsonism Relat Disord ; 16(3): 228-31, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19833540

RESUMO

The alpha-synuclein gene (SNCA) multiplication causes autosomal dominant Parkinson Disease (PD): triplication is associated with early-onset rapidly progressing parkinsonism with a strong likelihood of developing dementia, while duplication is associated with a less severe phenotype similar to idiopathic PD. We tested for SNCA multiplication 144 unrelated PD patients with a dominant family history. We identified one patient with SNCA duplication (0.7%). The SNCA-duplicated patient was a woman of 45 years of age with PD onset at 41 years of age. She experienced a rapidly progressive disease with early motor complications (on/off fluctuations and dyskinesias). Medical records confirmed that the proband's mother developed PD at 47 years of age and died at 63 with dementia. She experienced rapid progression in both motor and cognitive symptoms: development of dementia at 54 years of age, 7 years after onset. Although SNCA duplication is an unusual cause of familial PD testing for it is worthwhile. The clinical presentation of duplicated cases may be more aggressive than usual.


Assuntos
Duplicação Gênica , Predisposição Genética para Doença , Transtornos Parkinsonianos/genética , alfa-Sinucleína/genética , Adulto , Idoso , Saúde da Família , Feminino , Estudo de Associação Genômica Ampla/métodos , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Adulto Jovem
11.
Genet Test Mol Biomarkers ; 13(2): 209-17, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19371219

RESUMO

Mutations in the GJB2 gene, which encodes the gap-junction protein connexin 26, are the most common cause of nonsyndromic hearing loss (NSHL) and account for about 32% of cases. We analyzed 734 patients and identified mutations in 474/1468 chromosomes. Thirty-six different mutations and five polymorphisms were found in 269 NSHL subjects. Our data confirm 35delG as the most frequent GJB2 mutation in the Italian population, accounting for about 68% of all the mutated GJB2 alleles analyzed. We also identified two novel variants: the V156I mutation and the C>A change at nucleotide 684 in the 3'UTR of the gene. The GJB6 gene deletion, del(GJB6-D13S1830), which can cause HL in combination with GJB2 mutations in trans, was identified in three patients, while the del(GJB6-D13S1854) was not observed in our cohort of patients. We collected audiometric data from 200 patients with biallelic DFNB1 mutations or with dominant mutation in GJB2 to determine the degree of HL to correlate the genotypes with the audiological phenotypes.


Assuntos
Conexinas/genética , Grupo com Ancestrais do Continente Europeu/genética , Genótipo , Perda Auditiva/genética , Mutação , Distribuição por Idade , Alelos , Audiometria , Estudos de Coortes , Conexina 26 , Éxons , Frequência do Gene , Genes Dominantes , Genes Recessivos , Heterozigoto , Homozigoto , Humanos , Itália , Polimorfismo Genético , Análise de Sequência de DNA , Índice de Gravidade de Doença
12.
Laryngoscope ; 117(5): 821-4, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17473676

RESUMO

OBJECTIVES: Mutations in the GJB2 gene, encoding Connexin 26, can cause nonsyndromic recessive deafness or dominant hearing loss (HL) with or without keratoderma. The objective was to perform a molecular evaluation to establish the inherited pattern of deafness in the sporadic cases afferent to our center. METHODS: The subject was a 2-year-old Italian girl with nonsyndromic early onset HL. We performed DNA sequencing of the GJB2 gene and deletion analysis of the GJB6 gene in all family members. RESULTS: Direct sequencing of the gene showed a heterozygous C-->G transition at nucleotide 172 resulting in a proline to alanine amino acid substitution at codon 58 (P58A). The analyses indicate that the P58A mutation appeared de novo in the proband with a possible dominant effect. CONCLUSIONS: This mutation occurs in the first extracellular domain (EC1), which seems to be very important for connexon-connexon interaction and for the control of voltage gating of the channel. The de novo occurrence of an EC1 mutation in a sporadic case of deafness is consistent with the assumption that P58A can cause dominant HL.


Assuntos
Conexinas/genética , Perda Auditiva Neurossensorial/genética , Mutação de Sentido Incorreto , Conexina 26 , Análise Mutacional de DNA , Feminino , Genes Dominantes , Humanos , Lactente , Linhagem
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