RESUMO
Mutations causing dysfunction of tubulins and microtubule-associated proteins, also known as tubulinopathies, are a group of recently described entities that lead to complex brain malformations. Anatomical and functional consequences of the disruption of tubulins include microcephaly, combined with abnormal corticogenesis due to impaired migration or lamination and abnormal growth cone dynamics of projecting and callosal axons. Key imaging features of tubulinopathies are characterized by three major patterns of malformations of cortical development (MCD): lissencephaly, microlissencephaly, and dysgyria. Additional distinctive MRI features include dysmorphism of the basal ganglia, midline commissural structure hypoplasia or agenesis, and cerebellar and brainstem hypoplasia. Tubulinopathies can be diagnosed as early as 21-24 gestational weeks using imaging and neuropathology, with possible extreme microlissencephaly with an extremely thin cortex, lissencephaly with either thick or thin/intermediate cortex, and dysgyria combined with cerebellar hypoplasia, pons hypoplasia and corpus callosum dysgenesis. More than 100 MCD-associated mutations have been reported in TUBA1A, TUBB2B, or TUBB3 genes, whereas fewer than ten are known in other genes such TUBB2A, TUBB or TUBG1. Although these mutations are scattered along the α- and ß-tubulin sequences, recurrent mutations are consistently associated with almost identical cortical dysgenesis. Much of the evidence supports that these mutations alter the dynamic properties and functions of microtubules in several fashions. These include diminishing the abundance of functional tubulin heterodimers, altering GTP binding, altering longitudinal and lateral protofilament interactions, and impairing microtubule interactions with kinesin and/or dynein motors or with MAPs. In this review we discuss the recent advances in our understanding of the effects of mutations of tubulins and microtubule-associated proteins on human brain development and the pathogenesis of malformations of cortical development.
Assuntos
Lisencefalia , Microcefalia , Tubulina (Proteína) , Humanos , Deficiências do Desenvolvimento , Lisencefalia/genética , Lisencefalia/diagnóstico , Proteínas Associadas aos Microtúbulos , Mutação , Tubulina (Proteína)/genéticaRESUMO
Dedicator of cytokinesis (DOCK) proteins play a central role in actin cytoskeleton regulation. This is highlighted by the DOCK2 and DOCK8 deficiencies leading to actinopathies and immune deficiencies. DOCK8 and DOCK11 activate CDC42, a Rho-guanosine triphosphate hydrolases involved in actin cytoskeleton dynamics, among many cellular functions. The role of DOCK11 in human immune disease has been long suspected but, to the best of our knowledge, has never been described to date. We studied 8 male patients, from 7 unrelated families, with hemizygous DOCK11 missense variants leading to reduced DOCK11 expression. The patients were presenting with early-onset autoimmunity, including cytopenia, systemic lupus erythematosus, skin, and digestive manifestations. Patients' platelets exhibited abnormal ultrastructural morphology and spreading as well as impaired CDC42 activity. In vitro activated T cells and B-lymphoblastoid cell lines from patients exhibited aberrant protrusions and abnormal migration speed in confined channels concomitant with altered actin polymerization during migration. Knock down of DOCK11 recapitulated these abnormal cellular phenotypes in monocytes-derived dendritic cells and primary activated T cells from healthy controls. Lastly, in line with the patients' autoimmune manifestations, we also observed abnormal regulatory T-cell (Treg) phenotype with profoundly reduced FOXP3 and IKZF2 expression. Moreover, we found reduced T-cell proliferation and impaired STAT5B phosphorylation upon interleukin-2 stimulation of the patients' lymphocytes. In conclusion, DOCK11 deficiency is a new X-linked immune-related actinopathy leading to impaired CDC42 activity and STAT5 activation, and is associated with abnormal actin cytoskeleton remodeling as well as Treg phenotype, culminating in immune dysregulation and severe early-onset autoimmunity.
Assuntos
Doenças do Sistema Imunitário , Síndromes de Imunodeficiência , Humanos , Masculino , Citoesqueleto de Actina/metabolismo , Autoimunidade , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Doenças do Sistema Imunitário/metabolismo , Síndromes de Imunodeficiência/complicações , Síndromes de Imunodeficiência/genética , Linfócitos T ReguladoresRESUMO
Dysregulated transforming growth factor TGF-ß signaling underlies the pathogenesis of genetic disorders affecting the connective tissue such as Loeys-Dietz syndrome. Here, we report 12 individuals with bi-allelic loss-of-function variants in IPO8 who presented with a syndromic association characterized by cardio-vascular anomalies, joint hyperlaxity, and various degree of dysmorphic features and developmental delay as well as immune dysregulation; the individuals were from nine unrelated families. Importin 8 belongs to the karyopherin family of nuclear transport receptors and was previously shown to mediate TGF-ß-dependent SMADs trafficking to the nucleus in vitro. The important in vivo role of IPO8 in pSMAD nuclear translocation was demonstrated by CRISPR/Cas9-mediated inactivation in zebrafish. Consistent with IPO8's role in BMP/TGF-ß signaling, ipo8-/- zebrafish presented mild to severe dorso-ventral patterning defects during early embryonic development. Moreover, ipo8-/- zebrafish displayed severe cardiovascular and skeletal defects that mirrored the human phenotype. Our work thus provides evidence that IPO8 plays a critical and non-redundant role in TGF-ß signaling during development and reinforces the existing link between TGF-ß signaling and connective tissue defects.
Assuntos
Doenças Ósseas/etiologia , Doenças Cardiovasculares/etiologia , Doenças do Tecido Conjuntivo/etiologia , Imunidade Celular/imunologia , Mutação com Perda de Função , Perda de Heterozigosidade , beta Carioferinas/genética , Adolescente , Adulto , Animais , Doenças Ósseas/patologia , Doenças Cardiovasculares/patologia , Criança , Doenças do Tecido Conjuntivo/patologia , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Transdução de Sinais , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo , Adulto Jovem , Peixe-Zebra , beta Carioferinas/metabolismoRESUMO
Incontinentia pigmenti (IP, Bloch-Sulzberger syndrome) is a multisystem disorder which associates specific skin lesions that evolves in four stages, and occasionally, central nervous system, eye, hair, and teeth involvement. Familial (35%) and sporadic (65%) cases are caused by pathogenic variants in the IKBKG gene. Here we report an unusual family, where, in two half-sisters affected by typical IP, molecular genetic analysis identified a likely pathogenic non-sense variant in the IKBKG gene of one of the sisters, the other being not a carrier. The strong clinical conviction motivated further molecular genetic investigations, which led to the characterization of a second variant in this unique family. X chromosome inactivation studies demonstrated the paternal origin of these two de novo variants. For genes with frequent de novo mutations, the coexistence of different pathogenic mutations in the same family is a possibility, and constitutes a challenge for genetic counseling.
Assuntos
Quinase I-kappa B , Incontinência Pigmentar , Mutação , Linhagem , Humanos , Incontinência Pigmentar/genética , Incontinência Pigmentar/patologia , Quinase I-kappa B/genética , Feminino , Mutação/genética , Inativação do Cromossomo X/genética , Masculino , Recidiva , Fenótipo , Predisposição Genética para DoençaRESUMO
PURPOSE: Hyper activation of the JAK-STAT signaling underlies the pathophysiology of many human immune-mediated diseases. Herein, the study of 2 adult patients with SOCS1 haploinsufficiency illustrates the severe and pleomorphic consequences of its impaired regulation in the intestinal tract. METHODS: Two unrelated adult patients presented with gastrointestinal manifestations, one with Crohn's disease-like ileo-colic inflammation refractory to anti-TNF and the other with lymphocytic leiomyositis causing severe chronic intestinal pseudo-occlusion. Next-generation sequencing was used to identify the underlying monogenic defect. One patient received anti-IL-12/IL-23 treatment while the other received the JAK1 inhibitor, ruxolitinib. Peripheral blood, intestinal tissues, and serum samples were analyzed before-and-after JAK1 inhibitor therapy using mass cytometry, histology, transcriptomic, and Olink assay. RESULTS: Novel germline loss-of-function variants in SOCS1 were identified in both patients. The patient with Crohn-like disease achieved clinical remission with anti-IL-12/IL-23 treatment. In the second patient with lymphocytic leiomyositis, ruxolitinib induced rapid resolution of the obstructive symptoms, significant decrease of the CD8+ T lymphocyte muscular infiltrate, and normalization of serum and intestinal cytokines. Decreased frequencies of circulating Treg cells, MAIT cells, and NK cells, with altered CD56bright:CD16lo:CD16hi NK subtype ratios were not modified by ruxolitinib. CONCLUSION: SOCS1 haploinsufficiency can result in a broad spectrum of intestinal manifestations and need to be considered as differential diagnosis in cases of severe treatment-refractory enteropathies, including the rare condition of lymphocytic leiomyositis. This provides the rationale for genetic screening and considering JAK inhibitors in such cases.
Assuntos
Haploinsuficiência , Inibidores do Fator de Necrose Tumoral , Adulto , Humanos , Proteínas Supressoras da Sinalização de Citocina/genética , Interleucina-12 , Interleucina-23 , Proteína 1 Supressora da Sinalização de Citocina/genéticaRESUMO
Variants in aminoacyl-tRNA synthetases (ARSs) genes are associated to a broad spectrum of human inherited diseases. Patients with defective PheRS, encoded by FARSA and FARSB, display brain abnormalities, interstitial lung disease and facial dysmorphism. We investigated four children from two unrelated consanguineous families carrying two missense homozygous variants in FARSA with significantly reduced PheRS-mediated aminoacylation activity. In addition to the core ARS-phenotype, all patients showed an inflammatory profile associated with autoimmunity and interferon score, a clinical feature not ascribed to PheRS-deficient patients to date. JAK inhibition improved lung disease in one patient. Our findings expand the genetic and clinical spectrum of FARSA-related disease.
Assuntos
Aminoacil-tRNA Sintetases , Doença de Charcot-Marie-Tooth , Doenças Pulmonares Intersticiais , Aminoacil-tRNA Sintetases/genética , Doença de Charcot-Marie-Tooth/genética , Consanguinidade , Humanos , Doenças Pulmonares Intersticiais/genética , Fenótipo , SíndromeRESUMO
OBJECTIVES: The first ECCO-ESPGHAN guidelines for the medical management of pediatric Crohn disease (CD) were published in 2014. Whether their implementation, and the consequent increased use of an upfront anti-tumor necrosis factor therapy, have changed the course of the disease has not been investigated yet. We aimed at comparing the evolution of pediatric CD patients diagnosed and treated before and after 2014. METHODS: Single-center retrospective study including all children diagnosed with CD from January 2010 to December 2018. Patients diagnosed between 2010 and 2014 (group 1) were compared to those diagnosed after 2014 (group 2). For each patient, at baseline and every 6-month, number of relapses, the occurrence of complication, therapy received and biological parameters were noted, as well as any endoscopic or radiologic evaluation. RESULTS: One hundred and fifty-four patients were included in the analysis, 78 (51%) diagnosed after 2014. The cumulative probability of a relapse-free and surgery-free course was significantly higher for patients treated according to the guidelines (log rank hazard ratio [HR] = 1,818, P = 0.003 and HR = 3,15, 95% confidence interval, P = 0.04, respectively). Mucosal healing rate was significantly higher among patients of group 2 at 1 and 2âyears (P = 0.04 and P = 0.05, respectively), while no significant difference was observed for transmural healing rates, as well as for the risk of complications. CONCLUSIONS: The implementation of the 2014 CD guidelines appears to have a significant impact on disease outcomes, with a significantly lower risk for relapse and surgery, while no effect could be observed on the risk of developing complications.
Assuntos
Doença de Crohn , Criança , Doença de Crohn/diagnóstico , Humanos , Infliximab/uso terapêutico , Recidiva , Estudos Retrospectivos , Fator de Necrose Tumoral alfaRESUMO
BACKGROUND: It is important to identify patients with monogenic IBD as management may differ from classical IBD. In this position statement we formulate recommendations for the use of genomics in evaluating potential monogenic causes of IBD across age groups. METHODS: The consensus included paediatric IBD specialists from the Paediatric IBD Porto group of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and specialists from several monogenic IBD research consortia. We defined key topics and performed a systematic literature review to cover indications, technologies (targeted panel, exome and genome sequencing), gene panel setup, cost-effectiveness of genetic screening, and requirements for the clinical care setting. We developed recommendations that were voted upon by all authors and Porto group members (32 voting specialists). RESULTS: We recommend next-generation DNA-sequencing technologies to diagnose monogenic causes of IBD in routine clinical practice embedded in a setting of multidisciplinary patient care. Routine genetic screening is not recommended for all IBD patients. Genetic testing should be considered depending on age of IBD-onset (infantile IBD, very early-onset IBD, paediatric or young adult IBD), and further criteria, such as family history, relevant comorbidities, and extraintestinal manifestations. Genetic testing is also recommended in advance of hematopoietic stem cell transplantation. We developed a diagnostic algorithm that includes a gene panel of 75 monogenic IBD genes. Considerations are provided also for low resource countries. CONCLUSIONS: Genomic technologies should be considered an integral part of patient care to investigate patients at risk for monogenic forms of IBD.
Assuntos
Colite , Gastroenterologia , Doenças Inflamatórias Intestinais , Criança , Fenômenos Fisiológicos da Nutrição Infantil , Genômica , Humanos , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/genéticaAssuntos
Anticorpos Monoclonais Humanizados , Epidermólise Bolhosa , Humanos , Anticorpos Monoclonais Humanizados/uso terapêutico , Masculino , Feminino , Adulto , Epidermólise Bolhosa/tratamento farmacológico , Epidermólise Bolhosa/genética , Pessoa de Meia-Idade , Adulto Jovem , Adolescente , Resultado do Tratamento , Criança , Pré-EscolarRESUMO
OBJECTIVE: Early-onset inflammatory bowel diseases can result from a wide spectrum of rare mendelian disorders. Early molecular diagnosis is crucial in defining treatment and in improving life expectancy. Herein we aimed at defining the mechanism of an immunodeficiency-polyendrocrinopathy and enteropathy-X-linked (IPEX)-like disease combined with a severe immunodeficiency in 2 siblings born from distantly related parents. METHODS: Whole exome sequencing was performed on blood-extracted genomic DNA from the 2 affected children and their parents on the genomic platform of Institut IMAGINE. Candidate gene mutation was identified using the in-house software PolyWeb and confirmed by Sanger sequencing. Protein expression was determined by western blot. Flow cytometry was used to assess consequences of the mutation on lymphocyte phenotype and nuclear factor-kappa B (NF-κB) activation at diagnosis and after treatment by hematopoietic stem cell transplantation. RESULTS: We identified a homozygous missense mutation in mucosa-associated lymphoid tissue lymphoma translocation 1 gene (MALT1), which precluded protein expression. In keeping with the known function of MALT1, NF-κB-dependent lymphocyte activation was severely impaired. Moreover, there was a drastic reduction in Forkhead box P3 (FOXP3) regulatory T cells accounting for the IPEX-like phenotype. Following identification of the mutation, both children received hematopoietic stem cell transplantation, which permitted full clinical recovery. Immunological workup at 6 and 12 months after transplantation showed normal NF-κB activation and correction of regulatory T cells frequency. CONCLUSIONS: Along with FOXP3, interleukin 2 receptor alpha chain (IL2RA), and cytotoxic T-lymphocyte protein 4 precursor (CTLA-4) mutations, MALT1 deficiency should now be considered as a possible cause of IPEX-like syndrome associated with immunodeficiency that can be cured by hematopoietic stem cell transplantation.
Assuntos
Diabetes Mellitus Tipo 1/congênito , Diarreia/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças do Sistema Imunitário/congênito , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/deficiência , Mutação de Sentido Incorreto , Criança , Pré-Escolar , Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 1/genética , Diarreia/diagnóstico , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Marcadores Genéticos , Homozigoto , Humanos , Doenças do Sistema Imunitário/diagnóstico , Doenças do Sistema Imunitário/genética , Masculino , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/genética , IrmãosAssuntos
Duodeno/enzimologia , Doenças Inflamatórias Intestinais/genética , Janus Quinases/metabolismo , Mutação com Perda de Função , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/metabolismo , Idade de Início , Pré-Escolar , Duodeno/efeitos dos fármacos , Duodeno/patologia , Ativação Enzimática , Feminino , Predisposição Genética para Doença , Células HEK293 , Humanos , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/enzimologia , Inibidores de Janus Quinases/farmacologia , Janus Quinases/antagonistas & inibidores , Células Jurkat , Nitrilas , Fenótipo , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Pirazóis/farmacologia , Pirimidinas , Transdução de SinaisAssuntos
Enterocolite/tratamento farmacológico , Enterocolite/genética , Inibidores de Proteínas Quinases/uso terapêutico , Pirazóis/uso terapêutico , Fator de Transcrição STAT3/genética , Doença Crônica , Diarreia/etiologia , Enterocolite/complicações , Feminino , Mutação com Ganho de Função , Humanos , Nitrilas , Pirimidinas , Sequenciamento do Exoma , Adulto JovemRESUMO
OBJECTIVE: Anastomotic ulceration (AU) is a rare complication after intestinal resection and anastomosis, described mostly in children. The main symptom is occult bleeding, leading to iron-deficiency anemia, which is life threatening. METHODS: The present survey reports a series of patients with AU after intestinal resection in infancy, focusing on predictive factors, medical and surgical treatment options, and long-term outcomes. Eleven patients (7 boys) born between 1983 and 2005 with AU after an intestinal resection and anastomosis in infancy were included in this retrospective review. RESULTS: The diagnosis of AU was often delayed for several years. No predictive factor (including the primary disease, the length of the remnant bowel, and the loss of the ileocaecal valve) could be identified. Numerous treatment options, including antibiotics and anti-inflammatory drugs, proved to be ineffective to induce prolonged remission. Even after surgical resection, relapses were observed in 5/7 children. CONCLUSIONS: The mechanism leading to AU remains unknown. Contrary to previous reports with limited follow-up, no medical or surgical treatment could prevent recurrences. Because relapses may occur several years after treatment, long-term follow-up is needed.
Assuntos
Anastomose Cirúrgica/efeitos adversos , Enteropatias/cirurgia , Intestinos/patologia , Complicações Pós-Operatórias , Úlcera/etiologia , Antibacterianos/uso terapêutico , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Intestinos/cirurgia , Masculino , Recidiva , Estudos Retrospectivos , Úlcera/diagnóstico , Úlcera/tratamento farmacológicoRESUMO
The proximal part of the small intestine, including duodenum and jejunum, is not only dedicated to nutrient digestion and absorption but is also a highly regulated immune site exposed to environmental factors. Host-protective responses against pathogens and tolerance to food antigens are essential functions in the small intestine. The cellular ecology and molecular pathways to maintain those functions are complex. Maladaptation is highlighted by common immune-mediated diseases such as coeliac disease, environmental enteric dysfunction or duodenal Crohn's disease. An expanding spectrum of more than 100 rare monogenic disorders inform on causative molecular mechanisms of nutrient absorption, epithelial homeostasis and barrier function, as well as inflammatory immune responses and immune regulation. Here, after summarizing the architectural and cellular traits that underlie the functions of the proximal intestine, we discuss how the integration of tissue immunopathology and molecular mechanisms can contribute towards our understanding of disease and guide diagnosis. We propose an integrated mechanism-based taxonomy and discuss the latest experimental approaches to gain new mechanistic insight into these disorders with large disease burden worldwide as well as implications for therapeutic interventions.
Assuntos
Oxidases Duais/genética , Doenças Inflamatórias Intestinais/genética , Mutação , Idade de Início , Anti-Inflamatórios/uso terapêutico , Pré-Escolar , Análise Mutacional de DNA , Fármacos Gastrointestinais/uso terapêutico , Predisposição Genética para Doença , Hereditariedade , Humanos , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/tratamento farmacológico , Doenças Inflamatórias Intestinais/enzimologia , Masculino , Linhagem , Fenótipo , Indução de Remissão , Fatores de Risco , Resultado do TratamentoRESUMO
Mutations in UNC45A, a co-chaperone for myosins, were recently found causative of a syndrome combining cholestasis, diarrhea, loss of hearing and bone fragility. We generated induced pluripotent stem cells (iPSCs) from a patient with a homozygous missense mutation in UNC45A. Cells from this patient, which were reprogrammed using integration-free Sendaï virus, have normal karyotype, express pluripotency markers and are able to differentiate into the three germ cell layers.
Assuntos
Células-Tronco Pluripotentes Induzidas , Síndromes de Malabsorção , Mucolipidoses , Humanos , Mutação de Sentido Incorreto , Mutação , Peptídeos e Proteínas de Sinalização Intracelular/genéticaRESUMO
INTRODUCTION: Multiple chronic ulcers of small intestine are mainly ascribed to Crohn's disease. Among possible differential diagnoses are chronic ulcers of small bowel caused by abnormal activation of the prostaglandin pathway either in the archetypal but uncommon non-steroidal anti-inflammatory drug [NSAID]-induced enteropathy, or in rare monogenic disorders due to PLA2G4A and SLCO2A1 mutations. SLCO2A1 variants are responsible for CEAS [chronic enteropathy associated with SLCO2A1], a syndrome which was exclusively reported in patients of Asian origin. Herein, we report the case of two French female siblings, P1 and P2, with CEAS. CASE REPORT: P1 underwent iterative bowel resections [removing 1 m of small bowel in total] for recurrent strictures and perforations. Her sister P2 had a tight duodenal stricture which required partial duodenectomy. Next-generation sequencing was performed on P1's DNA and identified two compound heterozygous variants in exon 12 in SLCO2A1, which were also present in P2. CONCLUSION: CEAS can be detected within the European population and raises the question of its incidence and recognition outside Asia. Presence of intractable recurrent ulcerations of the small intestine, mimicking Crohn's disease with concentric strictures, should motivate a genetic search for SLCO2A1 mutations, particularly in the context of family history or consanguinity.