RESUMO
BACKGROUND: Most intrahepatic arterioportal fistulae (IAPF) are acquired. The few cases of congenital fistulae are diagnosed in infants and children. CASE SUMMARY: We report a 31-year-old female patient presenting with haematemesis and melena three weeks after delivering her second child. The patient had a 20-year history of abdominal distention and nausea. IAPF, along with splenomegaly and ascites, was found by Doppler sonography and confirmed by computed tomography angiography. The patient was treated with endovascular coil embolization, resulting in occlusion of the fistula. CONCLUSION: This was an unusual case of possible congenital IAPF that manifested during a second pregnancy and was complicated by portal hypertension.
RESUMO
Non-obstructive azoospermia accounts for 10-15% of male infertility, resulting in 60% of all cases of azoospermia and affecting about 1% of the male population. About 30% of these cases are due to Y chromosome microdeletions, chromosome abnormalities, or hormonal disorders. Pathogenic variants in genes on the sex chromosomes have key roles in spermatogenic failure. The co-occurrence of azoospermia and congenital cataracts ranges between 1 in 165,000 and 1 in 500,000. Our 28-year-old patient with normal intelligence and abnormally shaped teeth presented with both disorders. A microarray revealed a microdeletion at Xp23.13 with a whole NHS gene deletion as well as a contiguous deletion of two other genes [SCML1 and RAI2]. This observation represents the first report of non-obstructive azoospermia with congenital cataracts and a contiguous deletion of the SCML1 gene, a transcript of which is exclusively expressed in the testis. SCML1 is the putative culprit gene, which requires functional study or animal experiments. Our analysis of 60 known spermatogenesis failure-related genes by whole-exome sequencing revealed no other candidate. The Nance-Horan syndrome due to pathogenic variants in the NHS gene at Xp23.13 including whole gene deletion does not have azoospermia as a feature. Our report adds to the completeness of genetic counseling for an individual with azoospermia and congenital cataracts.
Assuntos
Azoospermia/genética , Catarata/congênito , Catarata/genética , Aberrações Cromossômicas , Doenças Genéticas Ligadas ao Cromossomo X/genética , Anormalidades Dentárias/genética , Adulto , Azoospermia/patologia , Catarata/patologia , Deleção Cromossômica , Cromossomos Humanos X/genética , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Humanos , Masculino , Oligospermia/genética , Oligospermia/patologia , Espermatogênese/genética , Testículo/crescimento & desenvolvimento , Testículo/patologia , Anormalidades Dentárias/patologiaRESUMO
PURPOSE: We evaluated the Exome Aggregation Consortium (ExAC) database as a control cohort to classify variants across a diverse set of genes spanning dominant and recessively inherited disorders. METHODS: The frequency of pathogenic variants in ExAC was compared with the estimated maximal pathogenic allele frequency (MPAF), based on the disease prevalence, penetrance, inheritance, allelic and locus heterogeneity of each gene. Additionally, the observed carrier frequency and the ethnicity-specific variant distribution were compared between ExAC and the published literature. RESULTS: The carrier frequency and ethnic distribution of pathogenic variants in ExAC were concordant with reported estimates. Of 871 pathogenic/likely pathogenic variants across 19 genes, only 3 exceeded the estimated MPAF. Eighty-four percent of variants with ExAC frequencies above the estimated MPAF were classified as "benign." Additionally, 20% of the cardiac and 19% of the Lynch syndrome gene variants originally classified as "VUS" occurred with ExAC frequencies above the estimated MPAF, making these suitable for reassessment. CONCLUSIONS: The ExAC database is a useful source for variant classification and is not overrepresented for pathogenic variants in the genes evaluated. However, the mutational spectrum, pseudogenes, genetic heterogeneity, and paucity of literature should be considered in deriving meaningful classifications using ExAC.Genet Med 18 8, 850-854.
Assuntos
Bases de Dados Genéticas , Etnicidade/genética , Variação Genética , Exoma , Frequência do Gene , Predisposição Genética para Doença , HumanosRESUMO
Epigenetic mechanisms mediating expression of the Runt-related transcription factor Runx2 are critical for controlling its osteogenic activity during skeletal development. Here, we characterized bona fide regulatory elements within 120 kbp of the endogenous bone-related Runx2 promoter (P1) in osteoblasts by genomic DNase I footprinting and chromatin immuno-precipitations (ChIPs). We identified a ~10 kbp genomic domain spanning the P1 promoter that interacts with acetylated histones H3 and H4 reflecting an open chromatin conformation in MC3T3 osteoblasts. This large chromatin domain contains a single major DNaseI hypersensitive (DHS) region that defines a 0.4 kbp "basal core" promoter. This region encompasses two endogenous genomic protein/DNA interaction sites (i.e., footprints at Activating Protein 1 [AP1], E-box and Runx motifs). Helix-Loop-Helix (HLH)/E-box occupancy and presence of the DHS region persists in several mesenchymal cell types, but AP1 site occupancy occurs only during S phase when Runx2 expression is minimal. Point-mutation of the HLH/E box dramatically reduces basal promoter activity. Our results indicate that the Runx2 P1 promoter utilizes two stable principal protein/DNA interaction domains associated with AP1 and HLH factors. These sites function together with dynamic and developmentally responsive sites in a major DHS region to support epigenetic control of bone-specific transcription when osteoblasts transition into a quiescent or differentiated state.
Assuntos
Subunidade alfa 1 de Fator de Ligação ao Core/genética , Sequências Hélice-Alça-Hélice/genética , Domínios e Motivos de Interação entre Proteínas/genética , Animais , Linhagem Celular , Cromatina/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Desoxirribonuclease I/metabolismo , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/fisiologia , Sequências Hélice-Alça-Hélice/fisiologia , Histonas/metabolismo , Mesoderma/metabolismo , Camundongos , Osteoblastos/metabolismo , Mutação Puntual , Regiões Promotoras Genéticas , Domínios e Motivos de Interação entre Proteínas/fisiologia , Fator de Transcrição AP-1/genética , Fator de Transcrição AP-1/metabolismoRESUMO
Identification of common molecular pathways affected by genetic variation in autism is important for understanding disease pathogenesis and devising effective therapies. Here, we test the hypothesis that rare genetic variation in the metabotropic glutamate-receptor (mGluR) signaling pathway contributes to autism susceptibility. Single-nucleotide variants in genes encoding components of the mGluR signaling pathway were identified by high-throughput multiplex sequencing of pooled samples from 290 non-syndromic autism cases and 300 ethnically matched controls on two independent next-generation platforms. This analysis revealed significant enrichment of rare functional variants in the mGluR pathway in autism cases. Higher burdens of rare, potentially deleterious variants were identified in autism cases for three pathway genes previously implicated in syndromic autism spectrum disorder, TSC1, TSC2, and SHANK3, suggesting that genetic variation in these genes also contributes to risk for non-syndromic autism. In addition, our analysis identified HOMER1, which encodes a postsynaptic density-localized scaffolding protein that interacts with Shank3 to regulate mGluR activity, as a novel autism-risk gene. Rare, potentially deleterious HOMER1 variants identified uniquely in the autism population affected functionally important protein regions or regulatory sequences and co-segregated closely with autism among children of affected families. We also identified rare ASD-associated coding variants predicted to have damaging effects on components of the Ras/MAPK cascade. Collectively, these findings suggest that altered signaling downstream of mGluRs contributes to the pathogenesis of non-syndromic autism.
Assuntos
Transtorno Autístico/genética , Variação Genética , Receptores de Glutamato Metabotrópico/genética , Transdução de Sinais/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Estudos de Casos e Controles , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Proteínas de Arcabouço Homer , Humanos , Masculino , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco , Proteína 1 do Complexo Esclerose Tuberosa , Proteína 2 do Complexo Esclerose Tuberosa , Proteínas Supressoras de Tumor/genéticaRESUMO
Gene testing in primary immune deficiencies (PIDs) once was limited to expert academic laboratories, but now is easily available to physicians with a broad range of clinical expertise. Such testing can establish or confirm a suspected diagnosis and also may predict future disease risk in advance of clinical signs and symptoms, inform reproductive decision making, and guide clinicians in selecting the most appropriate therapeutic options. This article, based on the authors' experience and a review of the published literature, discusses some of the advances and challenges currently encountered in the clinical molecular genetic diagnosis of PIDs.
Assuntos
Testes Genéticos , Síndromes de Imunodeficiência/diagnóstico , Síndromes de Imunodeficiência/genética , Mutação , Genes , Humanos , Síndromes de Imunodeficiência/imunologia , Análise de Sequência de DNARESUMO
Both activating and null mutations of proteins required for canonical WNT signaling have revealed the importance of this pathway for normal skeletal development. However, tissue-specific transcriptional mechanisms through which WNT signaling promotes the differentiation of bone-forming cells have yet to be identified. Here, we address the hypothesis that canonical WNT signaling and the bone-related transcription factor RUNX2/CBFA1/AML3 are functionally linked components of a pathway required for the onset of osteoblast differentiation. Our findings show that, in bone of the SFRP1 (secreted frizzled-related protein-1)-null mouse, which exhibits activated WNT signaling and a high bone mass phenotype, there is a significant increase in expression of T-cell factor (TCF)-1, Runx2, and the RUNX2 target gene osteocalcin. We demonstrate by mutational analysis that a functional TCF regulatory element responsive to canonical WNT signaling resides in the promoter of the Runx2 gene (-97 to -93). By chromatin immunoprecipitation, recruitment of beta-catenin and TCF1 to the endogenous Runx2 gene is shown. Coexpression of TCF1 with canonical WNT proteins resulted in a 2-5-fold activation of Runx2 promoter activity and a 7-8-fold induction of endogenous mRNA in mouse pluripotent mesenchymal and osteoprogenitor cells. This enhancement was abrogated by SFRP1. Taken together, our results provide evidence for direct regulation of Runx2 by canonical WNT signaling and suggest that Runx2 is a target of beta-catenin/TCF1 for the stimulation of bone formation. We propose that WNT/TCF1 signaling, like bone morphogenetic protein/transforming growth factor-beta signaling, activates Runx2 gene expression in mesenchymal cells for the control of osteoblast differentiation and skeletal development.
Assuntos
Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Osteogênese/genética , Transdução de Sinais , Animais , Diferenciação Celular , Células Cultivadas , Imunoprecipitação da Cromatina , Fibroblastos/metabolismo , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas de Membrana/metabolismo , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Transgênicos , Modelos Biológicos , Osteoblastos/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismoRESUMO
The Runx2 (CBFA1/AML3/PEBP2alphaA) transcription factor promotes skeletal cell differentiation, but it also has a novel cell growth regulatory activity in osteoblasts. We addressed here whether Runx2 activity is functionally linked to cell cycle-related mechanisms that control normal osteoblast proliferation and differentiation. We found that the levels of Runx2 gene transcription, mRNA and protein, are each up-regulated with cessation of cell growth (i.e. G(0)/G(1) transition) in preconfluent MC3T3 osteoblastic cells that do not yet express mature bone phenotypic gene expression. Cell growth regulation of Runx2 is also observed in primary calvarial osteoblasts and other osteoblastic cells with relatively normal cell growth characteristics, but not in osteosarcoma cells (e.g. SAOS-2 and ROS17/2.8). Runx2 levels are cell cycle-regulated in MC3T3 cells with respect to the G(1)/S and M/G(1) transitions: oscillates from maximal expression levels during early G(1) to minimal levels during early S phase and mitosis. However, in normal or immortalized (e.g. ATDC5) chondrocytic cells, Runx2 expression is suppressed during quiescence, and Runx2 levels are not regulated during G(1) and S phase in ATDC5 cells. Antisense or small interfering RNA-mediated reduction of the low physiological levels of Runx2 in proliferating MC3T3 cells does not accelerate cell cycle progression. However, forced expression of Runx2 suppresses proliferation of MC3T3 preosteoblasts or C2C12 mesenchymal cells which have osteogenic potential. Forced elevation of Runx2 in synchronized MC3T3 cells causes a delay in G(1). We propose that Runx2 levels and function are biologically linked to a cell growth-related G(1) transition in osteoblastic cells.
Assuntos
Ciclo Celular/fisiologia , Divisão Celular/fisiologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Regulação da Expressão Gênica , Osteoblastos/citologia , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia , Animais , Linhagem Celular , Linhagem Celular Transformada , Núcleo Celular/química , Subunidade alfa 1 de Fator de Ligação ao Core , Proteínas de Ligação a DNA/análise , Fase G1/fisiologia , Humanos , Cinética , Camundongos , Mitose , Osteoblastos/química , Osteoblastos/metabolismo , Osteossarcoma/metabolismo , Isoformas de Proteínas/genética , RNA Mensageiro/análise , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição AP-2 , Fatores de Transcrição/análise , Transfecção , Células Tumorais CultivadasRESUMO
Histones are the major protein component of nucleosomes, and de novo histone synthesis is essential for packaging newly replicated DNA into chromatin. As a result, histone gene expression is exquisitely and functionally coupled with DNA replication. Vastly divergent organisms such as yeast, fly and human all demonstrate the phylogenetically conserved propensity to maintain clustering of histone genes at one or more genomic loci. Although specific mechanisms are unclear, clustering is presumed to be important for common stringent transcriptional control of these genes at the G1/S phase transition. In this study, we describe a genomic duplication of the human histone gene cluster located at chromosome 1q21, which effectively doubles the previously known size and gene number of that cluster. The duplication persists in all examined tissues and cell lines, and the duplicated genes are transcriptionally active. Levels of messenger RNAs for duplicated histone H4 genes are high relative to those for non-duplicated H4 genes. Our data suggest that transcriptionally robust histone H4 genes may have been preferentially duplicated during evolution.
Assuntos
Histonas/genética , Família Multigênica/genética , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular Tumoral , Cromossomos Humanos Par 1/genética , Duplicação Gênica , Genes Duplicados/genética , Genoma Humano , Células HL-60 , Células HeLa , Humanos , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Homologia de Sequência do Ácido NucleicoAssuntos
Microscopia de Fluorescência/métodos , RNA/biossíntese , Coloração e Rotulagem/métodos , Uridina Trifosfato/análogos & derivados , Uridina Trifosfato/metabolismo , Anticorpos/imunologia , Permeabilidade da Membrana Celular , Núcleo Celular/química , Células Cultivadas , Citoesqueleto/metabolismo , Manejo de Espécimes , Transcrição GênicaAssuntos
Epitopos , Expressão Gênica , Proteínas/imunologia , Animais , Genes Reporter , Camundongos/embriologiaRESUMO
At the G(1)/S phase cell cycle transition, multiple histone genes are expressed to ensure that newly synthesized DNA is immediately packaged as chromatin. Here we have purified and functionally characterized the critical transcription factor HiNF-P, which is required for E2F-independent activation of the histone H4 multigene family. Using chromatin immunoprecipitation analysis and ligation-mediated PCR-assisted genomic sequencing, we show that HiNF-P interacts with conserved H4 cell cycle regulatory sequences in vivo. Antisense inhibition of HiNF-P reduces endogenous histone H4 gene expression. Furthermore, we find that HiNF-P utilizes NPAT/p220, a substrate of the cyclin E/cyclin-dependent kinase 2 (CDK2) kinase complex, as a key coactivator to enhance histone H4 gene transcription. The biological role of HiNF-P is reflected by impeded cell cycle progression into S phase upon antisense-mediated reduction of HiNF-P levels. Our results establish that HiNF-P is the ultimate link in a linear signaling pathway that is initiated with the growth factor-dependent induction of cyclin E/CDK2 kinase activity at the restriction point and culminates in the activation of histone H4 genes through HiNF-P at the G(1)/S phase transition.
Assuntos
Histonas/genética , Fase S/genética , Fase S/fisiologia , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA Complementar/genética , Regulação da Expressão Gênica , Células HeLa , Humanos , Dados de Sequência Molecular , Peso Molecular , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas Repressoras , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/isolamento & purificação , Dedos de Zinco/genéticaRESUMO
During the shutdown of proliferation and onset of differentiation of HL-60 promyelocytic leukemia cells, expression of the cell cycle-dependent histone genes is downregulated at the level of transcription. To address the mechanism by which this regulation occurs, we examined the chromatin structure of the histone H4/n (FO108, H4FN) gene locus. Micrococcal nuclease, DNase I, and restriction enzymes show similar cleavage sites and levels of sensitivity at the H4/n locus in both proliferating and differentiated HL-60 cells. In contrast, differentiation-related activation of the cyclin-dependent kinase inhibitor p21(cip1/WAF1) gene is accompanied by increased nuclease hypersensitivity. Chromatin immunoprecipitation assays of the H4/n gene reveal that acetylated histones H3 and H4 are maintained at the same levels in proliferating and postproliferative cells. Thus, the chromatin of the H4/n locus remains in an open state even after transcription ceases. Using ligation-mediated PCR to visualize genomic DNase I footprints at single-nucleotide resolution, we find that protein occupancy at the site II cell cycle element is selectively diminished in differentiated cells while the site I element remains occupied. Decreased occupancy of site II is reflected by loss of the site II binding protein HiNF-P. We conclude that H4 gene transcription during differentiation is downregulated by modulating protein interaction at the site II cell cycle element and that retention of an open chromatin conformation may be associated with site I occupancy.