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1.
Eur J Hum Genet ; 27(10): 1611-1618, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31278393

RESUMO

The developmental and epileptic encephalopathies (DEE) are a heterogeneous group of chronic encephalopathies frequently associated with rare de novo nonsynonymous coding variants in neuronally expressed genes. Here, we describe eight probands with a DEE phenotype comprising intellectual disability, epilepsy, and hypotonia. Exome trio analysis showed de novo variants in TRPM3, encoding a brain-expressed transient receptor potential channel, in each. Seven probands were identically heterozygous for a recurrent substitution, p.(Val837Met), in TRPM3's S4-S5 linker region, a conserved domain proposed to undergo conformational change during gated channel opening. The eighth individual was heterozygous for a proline substitution, p.(Pro937Gln), at the boundary between TRPM3's flexible pore-forming loop and an adjacent alpha-helix. General-population truncating variants and microdeletions occur throughout TRPM3, suggesting a pathomechanism other than simple haploinsufficiency. We conclude that de novo variants in TRPM3 are a cause of intellectual disability and epilepsy.

2.
Brain ; 141(9): 2576-2591, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30107533

RESUMO

Synaptotagmin 1 (SYT1) is a critical mediator of fast, synchronous, calcium-dependent neurotransmitter release and also modulates synaptic vesicle endocytosis. This paper describes 11 patients with de novo heterozygous missense mutations in SYT1. All mutations alter highly conserved residues, and cluster in two regions of the SYT1 C2B domain at positions Met303 (M303K), Asp304 (D304G), Asp366 (D366E), Ile368 (I368T) and Asn371 (N371K). Phenotypic features include infantile hypotonia, congenital ophthalmic abnormalities, childhood-onset hyperkinetic movement disorders, motor stereotypies, and developmental delay varying in severity from moderate to profound. Behavioural characteristics include sleep disturbance and episodic agitation. Absence of epileptic seizures and normal orbitofrontal head circumference are important negative features. Structural MRI is unremarkable but EEG disturbance is universal, characterized by intermittent low frequency high amplitude oscillations. The functional impact of these five de novo SYT1 mutations has been assessed by expressing rat SYT1 protein containing the equivalent human variants in wild-type mouse primary hippocampal cultures. All mutant forms of SYT1 were expressed at levels approximately equal to endogenous wild-type protein, and correctly localized to nerve terminals at rest, except for SYT1M303K, which was expressed at a lower level and failed to localize at nerve terminals. Following stimulation, SYT1I368T and SYT1N371K relocalized to nerve terminals at least as efficiently as wild-type SYT1. However, SYT1D304G and SYT1D366E failed to relocalize to nerve terminals following stimulation, indicative of impairments in endocytic retrieval and trafficking of SYT1. In addition, the presence of SYT1 variants at nerve terminals induced a slowing of exocytic rate following sustained action potential stimulation. The extent of disturbance to synaptic vesicle kinetics is mirrored by the severity of the affected individuals' phenotypes, suggesting that the efficiency of SYT1-mediated neurotransmitter release is critical to cognitive development. In summary, de novo dominant SYT1 missense mutations are associated with a recognizable neurodevelopmental syndrome, and further cases can now be diagnosed based on clinical features, electrophysiological signature and mutation characteristics. Variation in phenotype severity may reflect mutation-specific impact on the diverse physiological functions of SYT1.

3.
J Endocrinol ; 238(3): R131-R141, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29875163

RESUMO

The synthesis of glycogen represents a key pathway for the disposal of excess glucose while its degradation is crucial for providing energy during exercise and times of need. The importance of glycogen metabolism is also highlighted by human genetic disorders that are caused by mutations in the enzymes involved. In this review, we provide a basic summary on glycogen metabolism and some of the clinical aspects of the classical glycogen storage diseases. Disruptions in glycogen metabolism usually result in some level of dysfunction in the liver, muscle, heart, kidney and/or brain. Furthermore, the spectrum of symptoms observed is very broad, depending on the affected enzyme. Finally, we briefly discuss an aspect of glycogen metabolism related to the maintenance of its structure that seems to be gaining more recent attention. For example, in Lafora progressive myoclonus epilepsy, patients exhibit an accumulation of inclusion bodies in several tissues, containing glycogen with increased phosphorylation, longer chain lengths and irregular branch points. This abnormal structure is thought to make glycogen insoluble and resistant to degradation. Consequently, its accumulation becomes toxic to neurons, leading to cell death. Although the genes responsible have been identified, studies in the past two decades are only beginning to shed light into their molecular functions.

4.
Am J Hum Genet ; 97(6): 922-32, 2015 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-26637982

RESUMO

We describe an X-linked genetic syndrome associated with mutations in TAF1 and manifesting with global developmental delay, intellectual disability (ID), characteristic facial dysmorphology, generalized hypotonia, and variable neurologic features, all in male individuals. Simultaneous studies using diverse strategies led to the identification of nine families with overlapping clinical presentations and affected by de novo or maternally inherited single-nucleotide changes. Two additional families harboring large duplications involving TAF1 were also found to share phenotypic overlap with the probands harboring single-nucleotide changes, but they also demonstrated a severe neurodegeneration phenotype. Functional analysis with RNA-seq for one of the families suggested that the phenotype is associated with downregulation of a set of genes notably enriched with genes regulated by E-box proteins. In addition, knockdown and mutant studies of this gene in zebrafish have shown a quantifiable, albeit small, effect on a neuronal phenotype. Our results suggest that mutations in TAF1 play a critical role in the development of this X-linked ID syndrome.


Assuntos
Deficiências do Desenvolvimento/genética , Histona Acetiltransferases/genética , Deficiência Intelectual/genética , Doenças Neurodegenerativas/genética , Fatores Associados à Proteína de Ligação a TATA/genética , Fator de Transcrição TFIID/genética , Adolescente , Animais , Criança , Pré-Escolar , Deficiências do Desenvolvimento/metabolismo , Deficiências do Desenvolvimento/patologia , Modelos Animais de Doenças , Elementos E-Box , Facies , Família , Regulação da Expressão Gênica , Histona Acetiltransferases/metabolismo , Humanos , Lactente , Padrões de Herança , Deficiência Intelectual/metabolismo , Deficiência Intelectual/patologia , Masculino , Mutação , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Linhagem , Fenótipo , Transdução de Sinais , Fatores Associados à Proteína de Ligação a TATA/metabolismo , Fator de Transcrição TFIID/metabolismo , Adulto Jovem , Peixe-Zebra
5.
Am J Med Genet A ; 164A(7): 1795-801, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24700761

RESUMO

Duplications involving terminal Xq28 are a known cause of intellectual disability (ID) in males and in females with unfavorable X-inactivation patterns. Within Xq28, functional disomy of MECP2 causes a severe ID syndrome, however the dosage sensitivity of other Xq28 duplicated genes is less certain. Duplications involving the int22h-1/int22h-2 LCR-flanked region in distal Xq28 have recently been linked to a novel ID-associated phenotype. While evidence for the dosage sensitivity of this region is emerging, the phenotypic contribution of individual genes within the int22h-1/int22h-2-flanked region has yet to be determined. We report a familial case of a novel 774 kb Xq28-qter duplication, detected by cytogenomic microarray analysis, that partially overlaps the int22h-1/int22h-2-flanked region. This duplication and a 570 kb Xpter-p22.33 loss within the pseudoautosomal region were identified in three siblings, one female and two males, who presented with developmental delays/intellectual disability, mild dysmorphic features and short stature. Although unconfirmed, these results are suggestive of maternal inheritance of a recombinant X. We compare our clinical findings to patients with int22h-1/int22h-2-mediated duplications and discuss the potential pathogenicity of genes within the duplicated region, including those within the shared region of overlap, RAB39B and CLIC2.


Assuntos
Canais de Cloreto/genética , Duplicação Cromossômica , Cromossomos Humanos X , Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/genética , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Proteínas rab de Ligação ao GTP/genética , Hibridização Genômica Comparativa , Variações do Número de Cópias de DNA , Feminino , Estudos de Associação Genética , Humanos , Hibridização in Situ Fluorescente , Lactente , Linhagem , Irmãos
6.
Am J Med Genet A ; 161A(4): 717-31, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23495017

RESUMO

Deletions at 2p16.3 involving exons of NRXN1 are associated with susceptibility for autism and schizophrenia, and similar deletions have been identified in individuals with developmental delay and dysmorphic features. We have identified 34 probands with exonic NRXN1 deletions following referral for clinical microarray-based comparative genomic hybridization. To more firmly establish the full phenotypic spectrum associated with exonic NRXN1 deletions, we report the clinical features of 27 individuals with NRXN1 deletions, who represent 23 of these 34 families. The frequency of exonic NRXN1 deletions among our postnatally diagnosed patients (0.11%) is significantly higher than the frequency among reported controls (0.02%; P = 6.08 × 10(-7) ), supporting a role for these deletions in the development of abnormal phenotypes. Generally, most individuals with NRXN1 exonic deletions have developmental delay (particularly speech), abnormal behaviors, and mild dysmorphic features. In our cohort, autism spectrum disorders were diagnosed in 43% (10/23), and 16% (4/25) had epilepsy. The presence of NRXN1 deletions in normal parents and siblings suggests reduced penetrance and/or variable expressivity, which may be influenced by genetic, environmental, and/or stochastic factors. The pathogenicity of these deletions may also be affected by the location of the deletion within the gene. Counseling should appropriately represent this spectrum of possibilities when discussing recurrence risks or expectations for a child found to have a deletion in NRXN1.


Assuntos
Moléculas de Adesão Celular Neuronais/genética , Deleção de Genes , Proteínas do Tecido Nervoso/genética , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Adolescente , Adulto , Transtorno Autístico/genética , Criança , Pré-Escolar , Hibridização Genômica Comparativa , Deficiências do Desenvolvimento/genética , Éxons , Facies , Feminino , Interação Gene-Ambiente , Estudo de Associação Genômica Ampla , Humanos , Lactente , Deficiência Intelectual/genética , Masculino , Pessoa de Meia-Idade , Penetrância , Fenótipo , Esquizofrenia/genética , Adulto Jovem
7.
Am J Med Genet A ; 161A(3): 487-500, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23345203

RESUMO

The 8p23.1 duplication syndrome is a relatively rare genomic condition that has been confirmed with molecular cytogenetic methods in only 11 probands and five family members. Here, we describe another prenatal and five postnatal patients with de novo 8p23.1 duplications analyzed with oligonucleotide array comparative genomic hybridization (oaCGH). Of the common features, mild or moderate developmental delays and/or learning difficulties have been found in 11/12 postnatal probands, a variable degree of mild dysmorphism in 8/12 and congenital heart disease (CHD) in 4/5 prenatal and 3/12 postnatal probands. Behavioral problems, cleft lip and/or palate, macrocephaly, and seizures were confirmed as additional features among the new patients, and novel features included neonatal respiratory distress, attention deficit hyperactivity disorder (ADHD), ocular anomalies, balance problems, hypotonia, and hydrocele. The core duplication of 3.68 Mb contains 31 genes and microRNAs of which only GATA4, TNKS, SOX7, and XKR6 are likely to be dosage sensitive genes and MIR124-1 and MIR598 have been implicated in neurocognitive phenotypes. A combination of the duplication of GATA4, SOX7, and related genes may account for the variable penetrance of CHD. Two of the duplications were maternal and intrachromosomal in origin with maternal heterozygosity for the common inversion between the repeats in 8p23.1. These additional patients and the absence of the 8p23.1 duplications in published controls, indicate that the 8p23.1 duplication syndrome may now be considered a pathogenic copy number variation (pCNV) with an estimated population prevalence of 1 in 58,000.


Assuntos
Anormalidades Múltiplas/diagnóstico , Deficiências do Desenvolvimento/diagnóstico , Transtornos de Aprendizagem/diagnóstico , Trissomia/diagnóstico , Cariótipo Anormal , Anormalidades Múltiplas/genética , Adulto , Criança , Cromossomos Humanos Par 8/genética , Hibridização Genômica Comparativa , Deficiências do Desenvolvimento/genética , Feminino , Humanos , Lactente , Transtornos de Aprendizagem/genética , Masculino , Síndrome , Trissomia/genética
8.
Nat Genet ; 42(3): 203-9, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20154674

RESUMO

We report the identification of a recurrent, 520-kb 16p12.1 microdeletion associated with childhood developmental delay. The microdeletion was detected in 20 of 11,873 cases compared with 2 of 8,540 controls (P = 0.0009, OR = 7.2) and replicated in a second series of 22 of 9,254 cases compared with 6 of 6,299 controls (P = 0.028, OR = 2.5). Most deletions were inherited, with carrier parents likely to manifest neuropsychiatric phenotypes compared to non-carrier parents (P = 0.037, OR = 6). Probands were more likely to carry an additional large copy-number variant when compared to matched controls (10 of 42 cases, P = 5.7 x 10(-5), OR = 6.6). The clinical features of individuals with two mutations were distinct from and/or more severe than those of individuals carrying only the co-occurring mutation. Our data support a two-hit model in which the 16p12.1 microdeletion both predisposes to neuropsychiatric phenotypes as a single event and exacerbates neurodevelopmental phenotypes in association with other large deletions or duplications. Analysis of other microdeletions with variable expressivity indicates that this two-hit model might be more generally applicable to neuropsychiatric disease.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 16 , Deficiências do Desenvolvimento/genética , Modelos Genéticos , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Cromossomos Humanos Par 16/genética , Hibridização Genômica Comparativa/métodos , Família , Frequência do Gene , Humanos , Lactente , Análise de Sequência com Séries de Oligonucleotídeos , Linhagem , Fenótipo , Polimorfismo de Nucleotídeo Único , Recidiva , Índice de Gravidade de Doença
9.
Genet Med ; 7(1): 21-7, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15654224

RESUMO

PURPOSE: The goal of this 3-year pilot project was to increase accessibility to genetics educational and clinical services in Maine. METHODS: Southern Maine Genetics Services, Foundation for Blood Research in collaboration with Maine Telemedicine Services established telemedicine capacity to link with rural health care centers located in Northern, Central, and Southern Maine and public health nursing statewide for the provision of genetics clinical and educational services. Core partners included a rural family practice residency program, a rural pediatric practice in northern Maine, and public health nurses statewide. The telegenetics model created was based on development and implementation of a preventive and medical management technology solution, conducting a pilot study to collect data, and approaching insurance companies for reimbursement. Evaluation included surveys on the quality, acceptability, and usefulness of genetics services delivered via telemedicine, telephone interviews, and decision-making confidence evaluations. RESULTS: During the project period, 24 rural clinical sites participated. In total, 93 presentations were given, and 125 patients were evaluated. Sixty-four percent of patients evaluated were pediatric. Despite site coordinator efforts to complete satisfaction surveys, the provider and patient response level was low (18% and 25%, respectively). Of those evaluations received, provider and patient response to telegenetics was positive. Decision-making confidence for genetics and neurology consultants was high. Our experience contributes to the development of telegenetics models that can be used in other rural states.


Assuntos
Aconselhamento Genético , Saúde Pública/educação , Consulta Remota , Aconselhamento Genético/métodos , Aconselhamento Genético/tendências , Testes Genéticos/métodos , Testes Genéticos/tendências , Humanos , Maine , Projetos Piloto , Saúde Pública/métodos , Saúde Pública/tendências , Consulta Remota/métodos , Consulta Remota/tendências
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