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1.
Sci Adv ; 6(49)2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33268356

RESUMO

Although somatic mutations in Histone 3.3 (H3.3) are well-studied drivers of oncogenesis, the role of germline mutations remains unreported. We analyze 46 patients bearing de novo germline mutations in histone 3 family 3A (H3F3A) or H3F3B with progressive neurologic dysfunction and congenital anomalies without malignancies. Molecular modeling of all 37 variants demonstrated clear disruptions in interactions with DNA, other histones, and histone chaperone proteins. Patient histone posttranslational modifications (PTMs) analysis revealed notably aberrant local PTM patterns distinct from the somatic lysine mutations that cause global PTM dysregulation. RNA sequencing on patient cells demonstrated up-regulated gene expression related to mitosis and cell division, and cellular assays confirmed an increased proliferative capacity. A zebrafish model showed craniofacial anomalies and a defect in Foxd3-derived glia. These data suggest that the mechanism of germline mutations are distinct from cancer-associated somatic histone mutations but may converge on control of cell proliferation.

2.
J Genet Couns ; 29(6): 884-887, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32969094

RESUMO

To help advance research critical to the achievement of the National Society of Genetic Counselors' (NSGC) strategic objectives, coordination and prioritization of society resources are needed. NSGC convened a task force to advance research necessary for the achievement of our strategic objectives by reviewing existing society-supported research efforts identifying gaps in current research, and coordinating society resources, the task force was formed in order to coordinate and prioritize society resources to advance research critical to the achievement of our strategic objectives. The task force developed a research agenda outlining high-priority research questions for the next 5 years. The questions are organized into four domains: (a) Genetic Counseling Clients; (b) Genetic Counseling Process and Outcomes; (c) Value of Genetic Counseling Services; and (d) Access to Genetic Counseling Services. This framework can be used to advocate for research and funding priorities within NSGC and with other key research entities to stimulate the growth and advancement of the genetic counseling profession.

3.
Am J Med Genet A ; 182(8): 1906-1912, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32573057

RESUMO

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A-related leukodystrophy, Peroxisomal biogenesis disorders, POLR3-related Leukodystrophy, Vanishing White Matter, and Pelizaeus-Merzbacher Disease. Despite the relative frequency of these conditions, carrier-screening laboratories regularly test only 20 of the 55 leukodystrophy-related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.

4.
J Genet Couns ; 29(4): 574-586, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32298033

RESUMO

Clinical exome sequencing (CES) is an established method for genetic diagnosis and is used widely in clinical practice. Studies of the parental experience of CES, which inform guidelines for best practices for genetic counseling, have been predominately comprised of White, non-Latinx participants. The aim of this study was to explore the parental experiences of CES in a Latinx community and to understand how their experiences are influenced by culture and language. We conducted semi-structured interviews in English and Spanish with 38 Latinx parents of children who had CES. Some of the themes that emerged were common to those previously identified, including a sense of obligation to pursue testing and a mixed emotional response to their child's results. Parents who had lower education level and/or received care from a provider who did not share their language had more confusion about their child's CES results and greater dissatisfaction with care compared with parents who had higher education level and/or received care from a provider who spoke their language. We also found evidence of hampered shared decision making and/or disempowered patient decision making regarding CES testing. Our data suggest unique needs for Latinx families having CES, particularly those who are non-English speaking when an interpreter is used. Our data support the value in continuing to take steps to improve culturally competent care by improving interpretation services and recruiting and training a genetic workforce that is ethnically, linguistically, and culturally diverse.

5.
Mol Psychiatry ; 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32346159

RESUMO

Defects in histone methyltransferases (HMTs) are major contributing factors in neurodevelopmental disorders (NDDs). Heterozygous variants of SETD1A involved in histone H3 lysine 4 (H3K4) methylation were previously identified in individuals with schizophrenia. Here, we define the clinical features of the Mendelian syndrome associated with haploinsufficiency of SETD1A by investigating 15 predominantly pediatric individuals who all have de novo SETD1A variants. These individuals present with a core set of symptoms comprising global developmental delay and/or intellectual disability, subtle facial dysmorphisms, behavioral and psychiatric problems. We examined cellular phenotypes in three patient-derived lymphoblastoid cell lines with three variants: p.Gly535Alafs*12, c.4582-2_4582delAG, and p.Tyr1499Asp. These patient cell lines displayed DNA damage repair defects that were comparable to previously observed RNAi-mediated depletion of SETD1A. This suggested that these variants, including the p.Tyr1499Asp in the catalytic SET domain, behave as loss-of-function (LoF) alleles. Previous studies demonstrated a role for SETD1A in cell cycle control and differentiation. However, individuals with SETD1A variants do not show major structural brain defects or severe microcephaly, suggesting that defective proliferation and differentiation of neural progenitors is unlikely the single underlying cause of the disorder. We show here that the Drosophila melanogaster SETD1A orthologue is required in postmitotic neurons of the fly brain for normal memory, suggesting a role in post development neuronal function. Together, this study defines a neurodevelopmental disorder caused by dominant de novo LoF variants in SETD1A and further supports a role for H3K4 methyltransferases in the regulation of neuronal processes underlying normal cognitive functioning.

6.
Sci Adv ; 6(4): eaax0021, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32010779

RESUMO

Lysine acetyltransferase 6A (KAT6A) and its paralog KAT6B form stoichiometric complexes with bromodomain- and PHD finger-containing protein 1 (BRPF1) for acetylation of histone H3 at lysine 23 (H3K23). We report that these complexes also catalyze H3K23 propionylation in vitro and in vivo. Immunofluorescence microscopy and ATAC-See revealed the association of this modification with active chromatin. Brpf1 deletion obliterates the acylation in mouse embryos and fibroblasts. Moreover, we identify BRPF1 variants in 12 previously unidentified cases of syndromic intellectual disability and demonstrate that these cases and known BRPF1 variants impair H3K23 propionylation. Cardiac anomalies are present in a subset of the cases. H3K23 acylation is also impaired by cancer-derived somatic BRPF1 mutations. Valproate, vorinostat, propionate and butyrate promote H3K23 acylation. These results reveal the dual functionality of BRPF1-KAT6 complexes, shed light on mechanisms underlying related developmental disorders and various cancers, and suggest mutation-based therapy for medical conditions with deficient histone acylation.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ligação a DNA/metabolismo , Histona Acetiltransferases/metabolismo , Histonas/metabolismo , Neoplasias/etiologia , Neoplasias/metabolismo , Transtornos do Neurodesenvolvimento/etiologia , Transtornos do Neurodesenvolvimento/metabolismo , Acetilação , Proteínas Adaptadoras de Transdução de Sinal/genética , Sequência de Aminoácidos , Animais , Encéfalo/anormalidades , Encéfalo/diagnóstico por imagem , Linhagem Celular , Análise Mutacional de DNA , Proteínas de Ligação a DNA/genética , Suscetibilidade a Doenças , Predisposição Genética para Doença , Histona Acetiltransferases/genética , Humanos , Imagem por Ressonância Magnética , Camundongos , Camundongos Knockout , Modelos Biológicos , Complexos Multiproteicos/metabolismo , Mutação , Neoplasias/diagnóstico , Transtornos do Neurodesenvolvimento/diagnóstico , Fenótipo , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Processamento de Proteína Pós-Traducional , Síndrome
7.
Cold Spring Harb Perspect Med ; 10(10)2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570375

RESUMO

Genetic counselors (GCs) possess several core competencies that provide direct benefit in the clinical laboratory setting. Communication with clients about complex information such as test methodology or results and the skills of facilitation and translation of complex information were recognized as important skills early in the establishment of GCs in laboratories. The clinical expertise of GCs serves as the background and experience from which they facilitate complex laboratory cases. Early roles for GCs in the laboratory also included result reporting, case management, and test development. The scope of roles has broadened to include management, business development, education, telemedicine, research, and variant interpretation. With increasing value being placed on genetic counseling skills both in and outside of a clinical laboratory, the roles and positions of GCs will likely continue to expand.

8.
J Clin Invest ; 130(3): 1431-1445, 2020 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-31794431

RESUMO

Epigenetic integrity is critical for many eukaryotic cellular processes. An important question is how different epigenetic regulators control development and influence disease. Lysine acetyltransferase 8 (KAT8) is critical for acetylation of histone H4 at lysine 16 (H4K16), an evolutionarily conserved epigenetic mark. It is unclear what roles KAT8 plays in cerebral development and human disease. Here, we report that cerebrum-specific knockout mice displayed cerebral hypoplasia in the neocortex and hippocampus, along with improper neural stem and progenitor cell (NSPC) development. Mutant cerebrocortical neuroepithelia exhibited faulty proliferation, aberrant neurogenesis, massive apoptosis, and scant H4K16 propionylation. Mutant NSPCs formed poor neurospheres, and pharmacological KAT8 inhibition abolished neurosphere formation. Moreover, we describe KAT8 variants in 9 patients with intellectual disability, seizures, autism, dysmorphisms, and other anomalies. The variants altered chromobarrel and catalytic domains of KAT8, thereby impairing nucleosomal H4K16 acetylation. Valproate was effective for treating epilepsy in at least 2 of the individuals. This study uncovers a critical role of KAT8 in cerebral and NSPC development, identifies 9 individuals with KAT8 variants, and links deficient H4K16 acylation directly to intellectual disability, epilepsy, and other developmental anomalies.


Assuntos
Hipocampo/enzimologia , Histona Acetiltransferases/metabolismo , Deficiência Intelectual/enzimologia , Neocórtex/enzimologia , Células-Tronco Neurais/enzimologia , Acetilação , Animais , Células HEK293 , Hipocampo/patologia , Histona Acetiltransferases/genética , Humanos , Deficiência Intelectual/patologia , Camundongos , Camundongos Knockout , Neocórtex/patologia , Células-Tronco Neurais/patologia , Nucleossomos/genética , Nucleossomos/metabolismo
9.
Brain ; 143(1): 55-68, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31834374

RESUMO

MN1 encodes a transcriptional co-regulator without homology to other proteins, previously implicated in acute myeloid leukaemia and development of the palate. Large deletions encompassing MN1 have been reported in individuals with variable neurodevelopmental anomalies and non-specific facial features. We identified a cluster of de novo truncating mutations in MN1 in a cohort of 23 individuals with strikingly similar dysmorphic facial features, especially midface hypoplasia, and intellectual disability with severe expressive language delay. Imaging revealed an atypical form of rhombencephalosynapsis, a distinctive brain malformation characterized by partial or complete loss of the cerebellar vermis with fusion of the cerebellar hemispheres, in 8/10 individuals. Rhombencephalosynapsis has no previously known definitive genetic or environmental causes. Other frequent features included perisylvian polymicrogyria, abnormal posterior clinoid processes and persistent trigeminal artery. MN1 is encoded by only two exons. All mutations, including the recurrent variant p.Arg1295* observed in 8/21 probands, fall in the terminal exon or the extreme 3' region of exon 1, and are therefore predicted to result in escape from nonsense-mediated mRNA decay. This was confirmed in fibroblasts from three individuals. We propose that the condition described here, MN1 C-terminal truncation (MCTT) syndrome, is not due to MN1 haploinsufficiency but rather is the result of dominantly acting C-terminally truncated MN1 protein. Our data show that MN1 plays a critical role in human craniofacial and brain development, and opens the door to understanding the biological mechanisms underlying rhombencephalosynapsis.


Assuntos
Anormalidades Múltiplas/genética , Anormalidades Craniofaciais/genética , Deficiência Intelectual/genética , Transtornos do Desenvolvimento da Linguagem/genética , Malformações do Sistema Nervoso/genética , Transativadores/genética , Proteínas Supressoras de Tumor/genética , Anormalidades Múltiplas/diagnóstico por imagem , Adolescente , Artéria Basilar/anormalidades , Artéria Basilar/diagnóstico por imagem , Artérias Carótidas/anormalidades , Artérias Carótidas/diagnóstico por imagem , Vermis Cerebelar/anormalidades , Vermis Cerebelar/diagnóstico por imagem , Cerebelo/anormalidades , Cerebelo/diagnóstico por imagem , Criança , Pré-Escolar , Estudos de Coortes , Hibridização Genômica Comparativa , Anormalidades Craniofaciais/diagnóstico por imagem , Feminino , Fibroblastos/metabolismo , Humanos , Imageamento Tridimensional , Lactente , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Mutação , Malformações do Sistema Nervoso/diagnóstico por imagem , Degradação do RNAm Mediada por Códon sem Sentido , Polimicrogiria/diagnóstico por imagem , Polimicrogiria/genética , RNA-Seq , Reação em Cadeia da Polimerase em Tempo Real , Síndrome , Tomografia Computadorizada por Raios X , Sequenciamento Completo do Exoma , Sequenciamento Completo do Genoma
10.
Patient Educ Couns ; 103(1): 127-135, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31521424

RESUMO

OBJECTIVE: Growing use of clinical exome sequencing (CES) has led to an increased burden of genomic education. Self-guided educational tools can minimize the educational burden for genetic counselors (GCs). The effectiveness of these tools must be evaluated. METHODS: Parents of patients offered CES were randomized to watch educational videos before their visit or to receive routine care. Parents and GCs were surveyed about their experiences following the sessions. The responses of the video (n = 102) and no-video (n = 105) groups were compared. RESULTS: GCs reported no significant differences between parents in the video and no-video groups on genetics knowledge or CES knowledge. In contrast, parents' scores on genetics knowledge questions were lower in the video than no-video group (p = 0.007). Most parents reported the videos were informative, and the groups did not differ in satisfaction with GCs or decisions to have CES. CONCLUSION: GCs and parents perceived the videos to be beneficial. However, lower scores on genetics knowledge questions highlight the need for careful development of educational tools. PRACTICE IMPLICATIONS: Educational tools should be developed and assessed for effectiveness with the input of all stakeholders before widespread implementation. Better measures of the effectiveness of these educational tools are needed.

11.
Am J Hum Genet ; 105(3): 606-615, 2019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31474318

RESUMO

Cerebellar malformations are diverse congenital anomalies frequently associated with developmental disability. Although genetic and prenatal non-genetic causes have been described, no systematic analysis has been performed. Here, we present a large-exome sequencing study of Dandy-Walker malformation (DWM) and cerebellar hypoplasia (CBLH). We performed exome sequencing in 282 individuals from 100 families with DWM or CBLH, and we established a molecular diagnosis in 36 of 100 families, with a significantly higher yield for CBLH (51%) than for DWM (16%). The 41 variants impact 27 neurodevelopmental-disorder-associated genes, thus demonstrating that CBLH and DWM are often features of monogenic neurodevelopmental disorders. Though only seven monogenic causes (19%) were identified in more than one individual, neuroimaging review of 131 additional individuals confirmed cerebellar abnormalities in 23 of 27 genetic disorders (85%). Prenatal risk factors were frequently found among individuals without a genetic diagnosis (30 of 64 individuals [47%]). Single-cell RNA sequencing of prenatal human cerebellar tissue revealed gene enrichment in neuronal and vascular cell types; this suggests that defective vasculogenesis may disrupt cerebellar development. Further, de novo gain-of-function variants in PDGFRB, a tyrosine kinase receptor essential for vascular progenitor signaling, were associated with CBLH, and this discovery links genetic and non-genetic etiologies. Our results suggest that genetic defects impact specific cerebellar cell types and implicate abnormal vascular development as a mechanism for cerebellar malformations. We also confirmed a major contribution for non-genetic prenatal factors in individuals with cerebellar abnormalities, substantially influencing diagnostic evaluation and counseling regarding recurrence risk and prognosis.


Assuntos
Cerebelo/anormalidades , Cerebelo/diagnóstico por imagem , Estudos de Coortes , Feminino , Humanos , Masculino , Gravidez
12.
Nat Commun ; 10(1): 3094, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300657

RESUMO

AMPA receptors (AMPARs) are tetrameric ligand-gated channels made up of combinations of GluA1-4 subunits encoded by GRIA1-4 genes. GluA2 has an especially important role because, following post-transcriptional editing at the Q607 site, it renders heteromultimeric AMPARs Ca2+-impermeable, with a linear relationship between current and trans-membrane voltage. Here, we report heterozygous de novo GRIA2 mutations in 28 unrelated patients with intellectual disability (ID) and neurodevelopmental abnormalities including autism spectrum disorder (ASD), Rett syndrome-like features, and seizures or developmental epileptic encephalopathy (DEE). In functional expression studies, mutations lead to a decrease in agonist-evoked current mediated by mutant subunits compared to wild-type channels. When GluA2 subunits are co-expressed with GluA1, most GRIA2 mutations cause a decreased current amplitude and some also affect voltage rectification. Our results show that de-novo variants in GRIA2 can cause neurodevelopmental disorders, complementing evidence that other genetic causes of ID, ASD and DEE also disrupt glutamatergic synaptic transmission.


Assuntos
Deficiência Intelectual/genética , Transtornos do Neurodesenvolvimento/genética , Receptores de AMPA/genética , Adolescente , Adulto , Encéfalo/diagnóstico por imagem , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Heterozigoto , Humanos , Lactente , Mutação com Perda de Função , Imagem por Ressonância Magnética , Masculino , Transtornos do Neurodesenvolvimento/diagnóstico por imagem , Adulto Jovem
13.
Brain ; 142(9): 2617-2630, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31327001

RESUMO

The underpinnings of mild to moderate neurodevelopmental delay remain elusive, often leading to late diagnosis and interventions. Here, we present data on exome and genome sequencing as well as array analysis of 13 individuals that point to pathogenic, heterozygous, mostly de novo variants in WDFY3 (significant de novo enrichment P = 0.003) as a monogenic cause of mild and non-specific neurodevelopmental delay. Nine variants were protein-truncating and four missense. Overlapping symptoms included neurodevelopmental delay, intellectual disability, macrocephaly, and psychiatric disorders (autism spectrum disorders/attention deficit hyperactivity disorder). One proband presented with an opposing phenotype of microcephaly and the only missense-variant located in the PH-domain of WDFY3. Findings of this case are supported by previously published data, demonstrating that pathogenic PH-domain variants can lead to microcephaly via canonical Wnt-pathway upregulation. In a separate study, we reported that the autophagy scaffolding protein WDFY3 is required for cerebral cortical size regulation in mice, by controlling proper division of neural progenitors. Here, we show that proliferating cortical neural progenitors of human embryonic brains highly express WDFY3, further supporting a role for this molecule in the regulation of prenatal neurogenesis. We present data on Wnt-pathway dysregulation in Wdfy3-haploinsufficient mice, which display macrocephaly and deficits in motor coordination and associative learning, recapitulating the human phenotype. Consequently, we propose that in humans WDFY3 loss-of-function variants lead to macrocephaly via downregulation of the Wnt pathway. In summary, we present WDFY3 as a novel gene linked to mild to moderate neurodevelopmental delay and intellectual disability and conclude that variants putatively causing haploinsufficiency lead to macrocephaly, while an opposing pathomechanism due to variants in the PH-domain of WDFY3 leads to microcephaly.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Relacionadas à Autofagia/genética , Encéfalo/embriologia , Encéfalo/patologia , Variação Genética/genética , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/patologia , Proteínas Adaptadoras de Transdução de Sinal/química , Adolescente , Animais , Proteínas Relacionadas à Autofagia/química , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Tamanho do Órgão , Estrutura Secundária de Proteína
15.
Am J Hum Genet ; 104(3): 542-552, 2019 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-30827498

RESUMO

Polyglutamine expansions in the transcriptional co-repressor Atrophin-1, encoded by ATN1, cause the neurodegenerative condition dentatorubral-pallidoluysian atrophy (DRPLA) via a proposed novel toxic gain of function. We present detailed phenotypic information on eight unrelated individuals who have de novo missense and insertion variants within a conserved 16-amino-acid "HX repeat" motif of ATN1. Each of the affected individuals has severe cognitive impairment and hypotonia, a recognizable facial gestalt, and variable congenital anomalies. However, they lack the progressive symptoms typical of DRPLA neurodegeneration. To distinguish this subset of affected individuals from the DRPLA diagnosis, we suggest using the term CHEDDA (congenital hypotonia, epilepsy, developmental delay, digit abnormalities) to classify the condition. CHEDDA-related variants alter the particular structural features of the HX repeat motif, suggesting that CHEDDA results from perturbation of the structural and functional integrity of the HX repeat. We found several non-homologous human genes containing similar motifs of eight to 10 HX repeat sequences, including RERE, where disruptive variants in this motif have also been linked to a separate condition that causes neurocognitive and congenital anomalies. These findings suggest that perturbation of the HX motif might explain other Mendelian human conditions.


Assuntos
Motivos de Aminoácidos/genética , Variação Genética , Proteínas do Tecido Nervoso/genética , Transtornos Neurocognitivos/etiologia , Sequências Repetitivas de Ácido Nucleico , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Transtornos Neurocognitivos/classificação , Transtornos Neurocognitivos/patologia , Fenótipo , Prognóstico , Síndrome
16.
Eur J Hum Genet ; 27(7): 1081-1089, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30778173

RESUMO

Hexokinase 1 (HK1) phosphorylates glucose to glucose-6-phosphate, the first rate-limiting step in glycolysis. Homozygous and heterozygous variants in HK1 have been shown to cause autosomal recessive non-spherocytic hemolytic anemia, autosomal recessive Russe type hereditary motor and sensory neuropathy, and autosomal dominant retinitis pigmentosa (adRP). We report seven patients from six unrelated families with a neurodevelopmental disorder associated with developmental delay, intellectual disability, structural brain abnormality, and visual impairments in whom we identified four novel, de novo missense variants in the N-terminal half of HK1. Hexokinase activity in red blood cells of two patients was normal, suggesting that the disease mechanism is not due to loss of hexokinase enzymatic activity.


Assuntos
Eritrócitos , Neuropatia Hereditária Motora e Sensorial , Hexoquinase , Mutação de Sentido Incorreto , Linhagem , Adolescente , Adulto , Criança , Eritrócitos/enzimologia , Eritrócitos/patologia , Feminino , Neuropatia Hereditária Motora e Sensorial/enzimologia , Neuropatia Hereditária Motora e Sensorial/genética , Neuropatia Hereditária Motora e Sensorial/patologia , Hexoquinase/genética , Hexoquinase/metabolismo , Humanos , Lactente , Masculino , Retinite Pigmentosa/enzimologia , Retinite Pigmentosa/genética , Retinite Pigmentosa/patologia
17.
Brain ; 142(3): 542-559, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30668673

RESUMO

Biallelic pathogenic variants in PLPBP (formerly called PROSC) have recently been shown to cause a novel form of vitamin B6-dependent epilepsy, the pathophysiological basis of which is poorly understood. When left untreated, the disease can progress to status epilepticus and death in infancy. Here we present 12 previously undescribed patients and six novel pathogenic variants in PLPBP. Suspected clinical diagnoses prior to identification of PLPBP variants included mitochondrial encephalopathy (two patients), folinic acid-responsive epilepsy (one patient) and a movement disorder compatible with AADC deficiency (one patient). The encoded protein, PLPHP is believed to be crucial for B6 homeostasis. We modelled the pathogenicity of the variants and developed a clinical severity scoring system. The most severe phenotypes were associated with variants leading to loss of function of PLPBP or significantly affecting protein stability/PLP-binding. To explore the pathophysiology of this disease further, we developed the first zebrafish model of PLPHP deficiency using CRISPR/Cas9. Our model recapitulates the disease, with plpbp-/- larvae showing behavioural, biochemical, and electrophysiological signs of seizure activity by 10 days post-fertilization and early death by 16 days post-fertilization. Treatment with pyridoxine significantly improved the epileptic phenotype and extended lifespan in plpbp-/- animals. Larvae had disruptions in amino acid metabolism as well as GABA and catecholamine biosynthesis, indicating impairment of PLP-dependent enzymatic activities. Using mass spectrometry, we observed significant B6 vitamer level changes in plpbp-/- zebrafish, patient fibroblasts and PLPHP-deficient HEK293 cells. Additional studies in human cells and yeast provide the first empirical evidence that PLPHP is localized in mitochondria and may play a role in mitochondrial metabolism. These models provide new insights into disease mechanisms and can serve as a platform for drug discovery.


Assuntos
Epilepsia/etiologia , Proteínas/genética , Proteínas/metabolismo , Animais , Modelos Animais de Doenças , Epilepsia/fisiopatologia , Feminino , Células HEK293 , Humanos , Masculino , Fenótipo , Fosfato de Piridoxal/uso terapêutico , Piridoxina/deficiência , Vitamina B 6/metabolismo , Deficiência de Vitamina B 6/genética , Deficiência de Vitamina B 6/metabolismo , Peixe-Zebra
18.
Eur J Hum Genet ; 27(5): 747-759, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30664714

RESUMO

CYFIP2, encoding the evolutionary highly conserved cytoplasmic FMRP interacting protein 2, has previously been proposed as a candidate gene for intellectual disability and autism because of its important role linking FMRP-dependent transcription regulation and actin polymerization via the WAVE regulatory complex (WRC). Recently, de novo variants affecting the amino acid p.Arg87 of CYFIP2 were reported in four individuals with epileptic encephalopathy. We here report 12 independent patients harboring a variety of de novo variants in CYFIP2 broadening the molecular and clinical spectrum of a novel CYFIP2-related neurodevelopmental disorder. Using trio whole-exome or -genome sequencing, we identified 12 independent patients carrying a total of eight distinct de novo variants in CYFIP2 with a shared phenotype of intellectual disability, seizures, and muscular hypotonia. We detected seven different missense variants, of which two occurred recurrently (p.(Arg87Cys) and p.(Ile664Met)), and a splice donor variant in the last intron for which we showed exon skipping in the transcript. The latter is expected to escape nonsense-mediated mRNA decay resulting in a truncated protein. Despite the large spacing in the primary structure, the variants spatially cluster in the tertiary structure and are all predicted to weaken the interaction with WAVE1 or NCKAP1 of the actin polymerization regulating WRC-complex. Preliminary genotype-phenotype correlation indicates a profound phenotype in p.Arg87 substitutions and a more variable phenotype in other alterations. This study evidenced a variety of de novo variants in CYFIP2 as a novel cause of mostly severe intellectual disability with seizures and muscular hypotonia.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Citoplasma/metabolismo , Deficiência Intelectual/genética , Mutação/genética , Convulsões/genética , Criança , Pré-Escolar , Facies , Feminino , Humanos , Lactente , Masculino , Modelos Moleculares
19.
Am J Hum Genet ; 104(2): 203-212, 2019 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-30612693

RESUMO

Using exome sequencing, we have identified de novo variants in MAPK8IP3 in 13 unrelated individuals presenting with an overlapping phenotype of mild to severe intellectual disability. The de novo variants comprise six missense variants, three of which are recurrent, and three truncating variants. Brain anomalies such as perisylvian polymicrogyria, cerebral or cerebellar atrophy, and hypoplasia of the corpus callosum were consistent among individuals harboring recurrent de novo missense variants. MAPK8IP3 has been shown to be involved in the retrograde axonal-transport machinery, but many of its specific functions are yet to be elucidated. Using the CRISPR-Cas9 system to target six conserved amino acid positions in Caenorhabditis elegans, we found that two of the six investigated human alterations led to a significantly elevated density of axonal lysosomes, and five variants were associated with adverse locomotion. Reverse-engineering normalized the observed adverse effects back to wild-type levels. Combining genetic, phenotypic, and functional findings, as well as the significant enrichment of de novo variants in MAPK8IP3 within our total cohort of 27,232 individuals who underwent exome sequencing, we implicate de novo variants in MAPK8IP3 as a cause of a neurodevelopmental disorder with intellectual disability and variable brain anomalies.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Encéfalo/anormalidades , Encéfalo/metabolismo , Deficiência Intelectual/genética , Mutação , Proteínas do Tecido Nervoso/genética , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adolescente , Animais , Encéfalo/diagnóstico por imagem , Sistemas CRISPR-Cas , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Criança , Pré-Escolar , Simulação por Computador , Feminino , Humanos , Deficiência Intelectual/diagnóstico por imagem , Locomoção , Lisossomos/metabolismo , Masculino , Modelos Moleculares , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/metabolismo , Sequenciamento Completo do Exoma , Adulto Jovem
20.
Am J Hum Genet ; 104(1): 164-178, 2019 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-30580808

RESUMO

SMARCC2 (BAF170) is one of the invariable core subunits of the ATP-dependent chromatin remodeling BAF (BRG1-associated factor) complex and plays a crucial role in embryogenesis and corticogenesis. Pathogenic variants in genes encoding other components of the BAF complex have been associated with intellectual disability syndromes. Despite its significant biological role, variants in SMARCC2 have not been directly associated with human disease previously. Using whole-exome sequencing and a web-based gene-matching program, we identified 15 individuals with variable degrees of neurodevelopmental delay and growth retardation harboring one of 13 heterozygous variants in SMARCC2, most of them novel and proven de novo. The clinical presentation overlaps with intellectual disability syndromes associated with other BAF subunits, such as Coffin-Siris and Nicolaides-Baraitser syndromes and includes prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features such as hypertrichosis, thick eyebrows, thin upper lip vermilion, and upturned nose. Nine out of the fifteen individuals harbor variants in the highly conserved SMARCC2 DNA-interacting domains (SANT and SWIRM) and present with a more severe phenotype. Two of these individuals present cardiac abnormalities. Transcriptomic analysis of fibroblasts from affected individuals highlights a group of differentially expressed genes with possible roles in regulation of neuronal development and function, namely H19, SCRG1, RELN, and CACNB4. Our findings suggest a novel SMARCC2-related syndrome that overlaps with neurodevelopmental disorders associated with variants in BAF-complex subunits.


Assuntos
Deficiências do Desenvolvimento/complicações , Deficiências do Desenvolvimento/genética , Deficiência Intelectual/complicações , Deficiência Intelectual/genética , Mutação , Fatores de Transcrição/genética , Anormalidades Múltiplas/genética , Adolescente , Criança , Pré-Escolar , Proteínas de Ligação a DNA , Face/anormalidades , Feminino , Deformidades Congênitas da Mão/genética , Humanos , Masculino , Micrognatismo/genética , Pescoço/anormalidades , Síndrome
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