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1.
Ann Clin Transl Neurol ; 6(7): 1338-1344, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31353856

RESUMO

Focal cortical dysplasia (FCD) causes drug-resistant epilepsy and is associated with pathogenic variants in mTOR pathway genes. How germline variants cause these focal lesions is unclear, however a germline + somatic "2-hit" model is hypothesized. In a boy with drug-resistant epilepsy, FCD, and a germline DEPDC5 pathogenic variant, we show that a second-hit DEPDC5 variant is limited to dysmorphic neurons, and the somatic mutation load correlates with both dysmorphic neuron density and the epileptogenic zone. These findings provide new insights into the molecular and cellular correlates of FCD determining drug-resistant epilepsy and refine conceptualization of the epileptogenic zone.

2.
Am J Hum Genet ; 104(5): 914-924, 2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-30982611

RESUMO

Glypicans are a family of cell-surface heparan sulfate proteoglycans that regulate growth-factor signaling during development and are thought to play a role in the regulation of morphogenesis. Whole-exome sequencing of the Australian family that defined Keipert syndrome (nasodigitoacoustic syndrome) identified a hemizygous truncating variant in the gene encoding glypican 4 (GPC4). This variant, located in the final exon of GPC4, results in premature termination of the protein 51 amino acid residues prior to the stop codon, and in concomitant loss of functionally important N-linked glycosylation (Asn514) and glycosylphosphatidylinositol (GPI) anchor (Ser529) sites. We subsequently identified seven affected males from five additional kindreds with novel and predicted pathogenic variants in GPC4. Segregation analysis and X-inactivation studies in carrier females provided supportive evidence that the GPC4 variants caused the condition. Furthermore, functional studies of recombinant protein suggested that the truncated proteins p.Gln506∗ and p.Glu496∗ were less stable than the wild type. Clinical features of Keipert syndrome included a prominent forehead, a flat midface, hypertelorism, a broad nose, downturned corners of mouth, and digital abnormalities, whereas cognitive impairment and deafness were variable features. Studies of Gpc4 knockout mice showed evidence of the two primary features of Keipert syndrome: craniofacial abnormalities and digital abnormalities. Phylogenetic analysis demonstrated that GPC4 is most closely related to GPC6, which is associated with a bone dysplasia that has a phenotypic overlap with Keipert syndrome. Overall, we have shown that pathogenic variants in GPC4 cause a loss of function that results in Keipert syndrome, making GPC4 the third human glypican to be linked to a genetic syndrome.

3.
J Child Neurol ; 34(8): 472-476, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30963790

RESUMO

High throughput sequencing is discovering many likely causative genetic variants in individuals with cerebral palsy. Some investigators have suggested that this changes the clinical diagnosis of cerebral palsy and that these individuals should be removed from this diagnostic category. Cerebral palsy is a neurodevelopmental disorder diagnosed on clinical signs, not etiology. All nonprogressive permanent disorders of movement and posture attributed to disturbances that occurred in the developing fetal and infant brain can be described as "cerebral palsy." This definition of cerebral palsy should not be changed, whatever the cause. Reasons include stability, utility and accuracy of cerebral palsy registers, direct access to services, financial and social support specifically offered to families with cerebral palsy, and community understanding of the clinical diagnosis. Other neurodevelopmental disorders, for example, epilepsy, have not changed the diagnosis when genomic causes are found. The clinical diagnosis of cerebral palsy should remain, should prompt appropriate genetic studies and can subsequently be subclassified by etiology.

4.
Hum Mutat ; 40(5): 619-630, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30740813

RESUMO

The lipid phosphatase gene FIG4 is responsible for Yunis-Varón syndrome and Charcot-Marie-Tooth disease Type 4J, a peripheral neuropathy. We now describe four families with FIG4 variants and prominent abnormalities of central nervous system (CNS) white matter (leukoencephalopathy), with onset in early childhood, ranging from severe hypomyelination to mild undermyelination, in addition to peripheral neuropathy. Affected individuals inherited biallelic FIG4 variants from heterozygous parents. Cultured fibroblasts exhibit enlarged vacuoles characteristic of FIG4 dysfunction. Two unrelated families segregate the same G > A variant in the +1 position of intron 21 in the homozygous state in one family and compound heterozygous in the other. This mutation in the splice donor site of exon 21 results in read-through from exon 20 into intron 20 and truncation of the final 115 C-terminal amino acids of FIG4, with retention of partial function. The observed CNS white matter disorder in these families is consistent with the myelination defects in the FIG4 null mouse and the known role of FIG4 in oligodendrocyte maturation. The families described here the expanded clinical spectrum of FIG4 deficiency to include leukoencephalopathy.

6.
Dev Med Child Neurol ; 61(10): 1145-1152, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30680716

RESUMO

AIM: We aimed to systematically review the speech production, language, and oral function phenotype of bilateral perisylvian polymicrogyria (BPP), and examine the correlation between the topography of polymicrogyria and the severity of speech, language, and oral functional impairment. METHOD: A systematic search of MEDLINE, Embase, and PubMed databases was completed on 26th October 2017 using Medical Subject Heading terms synonymous with BPP and speech, language, or oral motor impairment. In total, 2411 papers were identified and 48 met inclusion criteria. RESULTS: Expressive and receptive language impairment and oral structural and functional deficits are frequent in BPP. Expressive deficits are frequently more severe than receptive. Only one study used formal assessments to demonstrate the presence of speech disorder, namely dysarthria. Seven studies reported an association between diffuse BPP and more severe language impairment. INTERPRETATION: Findings confirmed that language deficits are common in BPP, though assessment of the specific speech phenotype is limited. The paucity of high quality studies detailing the specific communication phenotype of BPP highlights the need for further investigation. Improving understanding of this phenotype will inform the development of targeted therapies and lead to better long-term outcomes. WHAT THIS PAPER ADDS: Speech, language, and oral functional impairments are common in individuals with bilateral perisylvian polymicrogyria. Posterior polymicrogyria is associated with a less severe language impairment than anterior polymicrogyria. Deeper investigation of speech is needed to understand implicated networks in this malformation.

7.
Cell Rep ; 25(10): 2729-2741.e6, 2018 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-30517861

RESUMO

The mammalian neocortex has undergone remarkable changes through evolution. A consequence of such rapid evolutionary events could be a trade-off that has rendered the brain susceptible to certain neurodevelopmental and neuropsychiatric conditions. We analyzed the exomes of 65 patients with the structural brain malformation periventricular nodular heterotopia (PH). De novo coding variants were observed in excess in genes defining a transcriptomic signature of basal radial glia, a cell type linked to brain evolution. In addition, we located two variants in human isoforms of two genes that have no ortholog in mice. Modulating the levels of one of these isoforms for the gene PLEKHG6 demonstrated its role in regulating neuroprogenitor differentiation and neuronal migration via RhoA, with phenotypic recapitulation of PH in human cerebral organoids. This suggests that this PLEKHG6 isoform is an example of a primate-specific genomic element supporting brain development.

8.
Eur J Hum Genet ; 2018 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-30089829

RESUMO

1. NAME OF DISEASE (SYNONYMS): Pontocerebellar hypoplasia type 9 (PCH9) and spastic paraplegia-63 (SPG63). 2. OMIM# OF THE DISEASE: 615809 and 615686. 3. NAME OF THE ANALYSED GENES OR DNA/CHROMOSOME SEGMENTS: AMPD2 at 1p13.3. 4. OMIM# OF THE GENE(S): 102771.

10.
Pediatr Dermatol ; 35(5): 575-581, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30020536

RESUMO

BACKGROUND: There is a lack of consensus regarding how best to screen children with facial port-wine stains for Sturge-Weber syndrome. Many favor brain magnetic resonance imaging, and adjunctive electroencephalography is increasingly used. However, the sensitivity, specificity, and negative and positive predictive value of magnetic resonance imaging and electroencephalography and whether screening improves seizure recognition is unclear. METHODS: A retrospective review of children with high-risk port-wine stains presenting consecutively to the outpatient laser clinic of a tertiary pediatric hospital between December 2015 and November 2016 was undertaken. Primary outcome measures were yield, accuracy, age of and protocols for screening magnetic resonance imaging and electroencephalography, type of and age at presenting seizure, and percentage referred to neurology. RESULTS: Of 126 patients with facial port-wine stains, 25.4% (32/126) were at high risk of Sturge-Weber syndrome (hemifacial, median, and forehead PWS phenotypes); 43.7% of these (14/32) underwent screening magnetic resonance imaging. Sturge-Weber syndrome was detected in 7.1% (1/14). Magnetic resonance imaging had false-negative results in 23.1% (3/13) of those screened. Screening magnetic resonance imaging had sensitivity of 25%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 76.9% for the detection of Sturge-Weber syndrome (hemifacial, median and forehead PWS phenotypes). Only one-third of those with false-negative magnetic resonance imaging were referred to neurology. Mean age of first seizure in those with false-negative screening magnetic resonance imaging was 28 months, vs 14 months in those not screened. Abnormal electroencephalographic signs were detected in the two infants who underwent presymptomatic electroencephalography. CONCLUSIONS: Findings from this small cohort of individuals with port-wine stains that put them at high risk of Sturge-Weber syndrome suggest that children with positive screening magnetic resonance imaging will almost certainly develop Sturge-Weber syndrome but that negative screening magnetic resonance imaging cannot exclude Sturge-Weber syndrome (in up to 23.1% of cases). False-negative magnetic resonance imaging may delay seizure recognition. Seizure education, monitoring, and consideration of adjunctive electroencephalography are important irrespective of magnetic resonance imaging findings.


Assuntos
Eletroencefalografia/métodos , Imagem por Ressonância Magnética/métodos , Mancha Vinho do Porto/complicações , Síndrome de Sturge-Weber/diagnóstico , Encéfalo/patologia , Criança , Pré-Escolar , Face/patologia , Feminino , Humanos , Lactente , Masculino , Programas de Rastreamento/métodos , Estudos Retrospectivos , Sensibilidade e Especificidade , Síndrome de Sturge-Weber/epidemiologia
11.
PLoS Genet ; 14(5): e1007281, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29738522

RESUMO

Periventricular nodular heterotopia (PVNH) is a malformation of cortical development commonly associated with epilepsy. We exome sequenced 202 individuals with sporadic PVNH to identify novel genetic risk loci. We first performed a trio-based analysis and identified 219 de novo variants. Although no novel genes were implicated in this initial analysis, PVNH cases were found overall to have a significant excess of nonsynonymous de novo variants in intolerant genes (p = 3.27x10-7), suggesting a role for rare new alleles in genes yet to be associated with the condition. Using a gene-level collapsing analysis comparing cases and controls, we identified a genome-wide significant signal driven by four ultra-rare loss-of-function heterozygous variants in MAP1B, including one de novo variant. In at least one instance, the MAP1B variant was inherited from a parent with previously undiagnosed PVNH. The PVNH was frontally predominant and associated with perisylvian polymicrogyria. These results implicate MAP1B in PVNH. More broadly, our findings suggest that detrimental mutations likely arising in immediately preceding generations with incomplete penetrance may also be responsible for some apparently sporadic diseases.


Assuntos
Predisposição Genética para Doença/genética , Mutação com Perda de Função , Proteínas Associadas aos Microtúbulos/genética , Heterotopia Nodular Periventricular/genética , Encéfalo/anormalidades , Encéfalo/diagnóstico por imagem , Feminino , Heterozigoto , Humanos , Imagem por Ressonância Magnética , Masculino , Sequenciamento Completo do Exoma/métodos
12.
Neurol Genet ; 4(3): e236, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29725622

RESUMO

Objective: To determine whether the GNAQ R183Q mutation is present in the forme fruste cases of Sturge-Weber syndrome (SWS) to establish a definitive molecular diagnosis. Methods: We used sensitive droplet digital PCR (ddPCR) to detect and quantify the GNAQ mutation in tissues from epilepsy surgery in 4 patients with leptomeningeal angiomatosis; none had ocular or cutaneous manifestations. Results: Low levels of the GNAQ mutation were detected in the brain tissue of all 4 cases-ranging from 0.42% to 7.1% frequency-but not in blood-derived DNA. Molecular evaluation confirmed the diagnosis in 1 case in which the radiologic and pathologic data were equivocal. Conclusions: We detected the mutation at low levels, consistent with mosaicism in the brain or skin (1.0%-18.1%) of classic cases. Our data confirm that the forme fruste is part of the spectrum of SWS, with the same molecular mechanism as the classic disease and that ddPCR is helpful where conventional diagnosis is uncertain.

13.
J Int Neuropsychol Soc ; 24(5): 445-455, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29510770

RESUMO

OBJECTIVES: Agenesis of the corpus callosum (AgCC), characterized by developmental absence of the corpus callosum, is one of the most common congenital brain malformations. To date, there are limited data on the neuropsychological consequences of AgCC and factors that modulate different outcomes, especially in children. This study aimed to describe general intellectual, academic, executive, social and behavioral functioning in a cohort of school-aged children presenting for clinical services to a hospital and diagnosed with AgCC. The influences of age, social risk and neurological factors were examined. METHODS: Twenty-eight school-aged children (8 to 17 years) diagnosed with AgCC completed tests of general intelligence (IQ) and academic functioning. Executive, social and behavioral functioning in daily life, and social risk, were estimated from parent and teacher rated questionnaires. MRI findings reviewed by a pediatric neurologist confirmed diagnosis and identified brain characteristics. Clinical details including the presence of epilepsy and diagnosed genetic condition were obtained from medical records. RESULTS: In our cohort, ~50% of children experienced general intellectual, academic, executive, social and/or behavioral difficulties and ~20% were functioning at a level comparable to typically developing children. Social risk was important for understanding variability in neuropsychological outcomes. Brain anomalies and complete AgCC were associated with lower mathematics performance and poorer executive functioning. CONCLUSIONS: This is the first comprehensive report of general intellectual, academic, executive social and behavioral consequences of AgCC in school-aged children. The findings have important clinical implications, suggesting that support to families and targeted intervention could promote positive neuropsychological functioning in children with AgCC who come to clinical attention. (JINS, 2018, 24, 445-455).

14.
Neurobiol Dis ; 114: 184-193, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29481864

RESUMO

Mutations in DEPDC5 and NPRL3 subunits of GATOR1, a modulator of mechanistic target of rapamycin (mTOR), are linked to malformations of cortical development (MCD). Brain specimens from these individuals reveal abnormal cortical lamination, altered cell morphology, and hyperphosphorylation of ribosomal S6 protein (PS6), a marker for mTOR activation. While numerous studies have examined GATOR1 subunit function in non-neuronal cell lines, few have directly assessed loss of GATOR1 subunit function in neuronal cell types. We hypothesized that DEPDC5 or NPRL3 shRNA-mediated knockdown (DEPDC5/NPRL3 KD) leads to inappropriate functional activation of mTOR and mTOR-dependent alterations in neuronal morphology. Neuronal size was determined in human specimens harboring DEPDC5 or NPRL3 mutations resected for epilepsy treatment. DEPDC5/NPRL3 KD effects on cell size, filopodial extension, subcellular mTOR complex 1 (mTORC1) localization, and mTORC1 activation during nutrient deprivation were assayed in mouse neuroblastoma cells (N2aC) and mouse subventricular zone derived neural progenitor cells (mNPCs). mTORC1-dependent effects of DEPDC5/NPRL3 KD were determined using the mTOR inhibitor rapamycin. Changes in mTOR subcellular localization and mTORC1 pathway activation following DEPDC5/NPRL3 KD were determined by examining the proximity of mTOR to the lysosomal surface during amino acid starvation. Neurons exhibiting PS6 immunoreactivity (Ser 235/236) in human specimens were 1.5× larger than neurons in post-mortem control samples. DEPDC5/NPRL3 KD caused mTORC1, but not mTORC2, hyperactivation, soma enlargement, and increased filopodia in N2aC and mNPCs compared with wildtype cells. DEPDC5/NPRL3 KD led to inappropriate mTOR localization at the lysosome along with constitutive mTOR activation following amino acid deprivation. DEPDC5/NPRL3 KD effects on morphology and functional mTOR activation were reversed by rapamycin. mTOR-dependent effects of DEPDC5/NPRL3 KD on morphology and subcellular localization of mTOR in neurons suggests that loss-of-function in GATOR1 subunits may play a role in MCD formation during fetal brain development.

15.
Cell Rep ; 22(5): 1105-1114, 2018 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-29386099

RESUMO

Avoidance of environmental dangers depends on nociceptive topognosis, or the ability to localize painful stimuli. This is proposed to rely on somatotopic maps arising from topographically organized point-to-point connections between the body surface and the CNS. To determine the role of topographic organization of spinal ascending projections in nociceptive topognosis, we generated a conditional knockout mouse lacking expression of the netrin1 receptor DCC in the spinal cord. These mice have an increased number of ipsilateral spinothalamic connections and exhibit aberrant activation of the somatosensory cortex in response to unilateral stimulation. Furthermore, spinal cord-specific Dcc knockout animals displayed mislocalized licking responses to formalin injection, indicating impaired topognosis. Similarly, humans with DCC mutations experience bilateral sensation evoked by unilateral somatosensory stimulation. Collectively, our results constitute functional evidence of the importance of topographic organization of spinofugal connections for nociceptive topognosis.

16.
J Med Genet ; 55(2): 104-113, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29097605

RESUMO

BACKGROUND: De novo mutations in PURA have recently been described to cause PURA syndrome, a neurodevelopmental disorder characterised by severe intellectual disability (ID), epilepsy, feeding difficulties and neonatal hypotonia. OBJECTIVES: To delineate the clinical spectrum of PURA syndrome and study genotype-phenotype correlations. METHODS: Diagnostic or research-based exome or Sanger sequencing was performed in individuals with ID. We systematically collected clinical and mutation data on newly ascertained PURA syndrome individuals, evaluated data of previously reported individuals and performed a computational analysis of photographs. We classified mutations based on predicted effect using 3D in silico models of crystal structures of Drosophila-derived Pur-alpha homologues. Finally, we explored genotype-phenotype correlations by analysis of both recurrent mutations as well as mutation classes. RESULTS: We report mutations in PURA (purine-rich element binding protein A) in 32 individuals, the largest cohort described so far. Evaluation of clinical data, including 22 previously published cases, revealed that all have moderate to severe ID and neonatal-onset symptoms, including hypotonia (96%), respiratory problems (57%), feeding difficulties (77%), exaggerated startle response (44%), hypersomnolence (66%) and hypothermia (35%). Epilepsy (54%) and gastrointestinal (69%), ophthalmological (51%) and endocrine problems (42%) were observed frequently. Computational analysis of facial photographs showed subtle facial dysmorphism. No strong genotype-phenotype correlation was identified by subgrouping mutations into functional classes. CONCLUSION: We delineate the clinical spectrum of PURA syndrome with the identification of 32 additional individuals. The identification of one individual through targeted Sanger sequencing points towards the clinical recognisability of the syndrome. Genotype-phenotype analysis showed no significant correlation between mutation classes and disease severity.

17.
Am J Med Genet A ; 176(1): 56-67, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29150892

RESUMO

PURA syndrome is a recently described developmental encephalopathy presenting with neonatal hypotonia, feeding difficulties, global developmental delay, severe intellectual disability, and frequent apnea and epilepsy. We describe 18 new individuals with heterozygous sequence variations in PURA. A neuromotor disorder starting with neonatal hyptonia, but ultimately allowing delayed progression to walking, was present in nearly all individuals. Congenital apnea was present in 56% during infancy, but all cases in this cohort resolved during the first year of life. Feeding difficulties were frequently reported, with gastrostomy tube placement required in 28%. Epilepsy was present in 50% of the subjects, including infantile spasms and Lennox-Gastaut syndrome. Skeletal complications were found in 39%. Disorders of gastrointestinal motility and nystagmus were also recurrent features. Autism was diagnosed in one individual, potentially expanding the neurodevelopmental phenotype associated with this syndrome. However, we did not find additional PURA sequence variations in a cohort of 120 subjects with autism. We also present the first neuropathologic studies of PURA syndrome, and describe chronic inflammatory changes around the arterioles within the deep white matter. We did not find significant correlations between mutational class and severity, nor between location of the sequence variation in PUR repeat domains. Further studies are required in larger cohorts of subjects with PURA syndrome to clarify these genotype-phenotype associations.


Assuntos
Encefalopatias/diagnóstico , Encefalopatias/genética , Proteínas de Ligação a DNA/genética , Estudos de Associação Genética , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Fenótipo , Fatores de Transcrição/genética , Adolescente , Adulto , Criança , Pré-Escolar , Deleção Cromossômica , Cromossomos Humanos Par 5 , Análise Mutacional de DNA , Gerenciamento Clínico , Epilepsia , Facies , Feminino , Humanos , Lactente , Imagem por Ressonância Magnética/métodos , Masculino , Síndrome , Substância Branca/patologia , Sequenciamento Completo do Exoma , Adulto Jovem
18.
Pediatr Dermatol ; 35(1): 30-42, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29034507

RESUMO

Infants with a high-risk distribution of port-wine stains are commonly screened for Sturge-Weber syndrome using brain magnetic resonance imaging. There is no consensus about which port-wine stain phenotypes to screen, optimal timing, screening sensitivity, or whether presymptomatic diagnosis improves neurodevelopmental outcomes. This state-of-the-art review examines the evidence in favor of screening for Sturge-Weber syndrome, based on its effect on neurodevelopmental outcomes, against the risks and limitations of screening magnetic resonance imaging and electroencephalography. A literature search of PubMed/MEDLINE was conducted between January 2005 and May 2017 using key search terms. Relevant articles published in English were reviewed; 34 articles meeting the search criteria were analyzed according to the following outcome measures: neurodevelopmental outcome benefit of screening, diagnostic yield, financial costs, procedural risks, and limitations of screening magnetic resonance imaging and electroencephalography. There is no evidence that a presymptomatic Sturge-Weber syndrome diagnosis with magnetic resonance imaging results in better neurodevelopmental outcomes. The utility of electroencephalographic screening is also unestablished. In Sturge-Weber syndrome, neurodevelopmental outcomes depend on prompt recognition of neurologic red flags and early seizure control. Small numbers and a lack of prospective randomized controlled trials limit these findings. For infants with port-wine stain involving skin derived from the frontonasal placode (forehead and hemifacial phenotypes), we recommend early referral to a pediatric neurologist for parental education, counselling, and monitoring for neurologic red flags and seizures and consideration of electroencephalography regardless of whether magnetic resonance imaging is performed or its findings.


Assuntos
Eletroencefalografia/métodos , Imagem por Ressonância Magnética/métodos , Programas de Rastreamento/métodos , Mancha Vinho do Porto/etiologia , Síndrome de Sturge-Weber/diagnóstico , Encéfalo/patologia , Eletroencefalografia/economia , Humanos , Lactente , Imagem por Ressonância Magnética/economia , Programas de Rastreamento/economia , Neuroimagem/economia , Neuroimagem/métodos , Convulsões/diagnóstico , Convulsões/tratamento farmacológico , Convulsões/etiologia
19.
Hum Mutat ; 39(1): 103-113, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29024177

RESUMO

Loss-of-function mutations in the X-linked gene FLNA can lead to abnormal neuronal migration, vascular and cardiac defects, and congenital intestinal pseudo-obstruction (CIPO), the latter characterized by anomalous intestinal smooth muscle layering. Survival in male hemizygotes for such mutations is dependent on retention of residual FLNA function but it is unclear why a subgroup of males with mutations in the 5' end of the gene can present with CIPO alone. Here, we demonstrate evidence for the presence of two FLNA isoforms differing by 28 residues at the N-terminus initiated at ATG+1 and ATG+82 . A male with CIPO (c.18_19del) exclusively expressed FLNA ATG+82 , implicating the longer protein isoform (ATG+1 ) in smooth muscle development. In contrast, mutations leading to reduction of both isoforms are associated with compound phenotypes affecting the brain, heart, and intestine. RNA-seq data revealed three distinct transcription start sites, two of which produce a protein isoform utilizing ATG+1 while the third utilizes ATG+82 . Transcripts sponsoring translational initiation at ATG+1 predominate in intestinal smooth muscle, and are more abundant compared with the level measured in fibroblasts. Together these observations describe a new mechanism of tissue-specific regulation of FLNA that could reflect the differing mechanical requirements of these cell types during development.


Assuntos
Filaminas/genética , Estudos de Associação Genética , Heterogeneidade Genética , Mutação com Perda de Função , Fenótipo , Transcrição Genética , Adolescente , Encéfalo/anormalidades , Encéfalo/diagnóstico por imagem , Criança , Sequência Conservada , Análise Mutacional de DNA , Feminino , Filaminas/química , Filaminas/metabolismo , Trato Gastrointestinal/metabolismo , Expressão Gênica , Humanos , Imagem por Ressonância Magnética , Masculino , Músculo Liso/metabolismo , Isoformas de Proteínas , Adulto Jovem
20.
Hum Mutat ; 39(1): 23-39, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29068161

RESUMO

The deleted in colorectal cancer (DCC) gene encodes the netrin-1 (NTN1) receptor DCC, a transmembrane protein required for the guidance of commissural axons. Germline DCC mutations disrupt the development of predominantly commissural tracts in the central nervous system (CNS) and cause a spectrum of neurological disorders. Monoallelic, missense, and predicted loss-of-function DCC mutations cause congenital mirror movements, isolated agenesis of the corpus callosum (ACC), or both. Biallelic, predicted loss-of-function DCC mutations cause developmental split brain syndrome (DSBS). Although the underlying molecular mechanisms leading to disease remain poorly understood, they are thought to stem from reduced or perturbed NTN1 signaling. Here, we review the 26 reported DCC mutations associated with abnormal CNS development in humans, including 14 missense and 12 predicted loss-of-function mutations, and discuss their associated clinical characteristics and diagnostic features. We provide an update on the observed genotype-phenotype relationships of congenital mirror movements, isolated ACC and DSBS, and correlate this to our current understanding of the biological function of DCC in the development of the CNS. All mutations and their associated phenotypes were deposited into a locus-specific LOVD (https://databases.lovd.nl/shared/genes/DCC).


Assuntos
Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Genes DCC , Estudos de Associação Genética , Mutação , Fenótipo , Agenesia do Corpo Caloso , Sequência de Aminoácidos , Sítios de Ligação , Sequência Conservada , Bases de Dados Genéticas , Humanos , Imagem por Ressonância Magnética , Modelos Moleculares , Netrina-1/química , Netrina-1/metabolismo , Ligação Proteica , Conformação Proteica , Domínios Proteicos/genética , Síndrome
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