RESUMEN
Cell adhesion molecules are membrane-bound proteins predominantly expressed in the central nervous system along principal axonal pathways with key roles in nervous system development, neural cell differentiation and migration, axonal growth and guidance, myelination, and synapse formation. Here, we describe ten affected individuals with bi-allelic variants in the neuronal cell adhesion molecule NRCAM that lead to a neurodevelopmental syndrome of varying severity; the individuals are from eight families. This syndrome is characterized by developmental delay/intellectual disability, hypotonia, peripheral neuropathy, and/or spasticity. Computational analyses of NRCAM variants, many of which cluster in the third fibronectin type III (Fn-III) domain, strongly suggest a deleterious effect on NRCAM structure and function, including possible disruption of its interactions with other proteins. These findings are corroborated by previous in vitro studies of murine Nrcam-deficient cells, revealing abnormal neurite outgrowth, synaptogenesis, and formation of nodes of Ranvier on myelinated axons. Our studies on zebrafish nrcamaΔ mutants lacking the third Fn-III domain revealed that mutant larvae displayed significantly altered swimming behavior compared to wild-type larvae (p < 0.03). Moreover, nrcamaΔ mutants displayed a trend toward increased amounts of α-tubulin fibers in the dorsal telencephalon, demonstrating an alteration in white matter tracts and projections. Taken together, our study provides evidence that NRCAM disruption causes a variable form of a neurodevelopmental disorder and broadens the knowledge on the growing role of the cell adhesion molecule family in the nervous system.
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Trastornos del Neurodesarrollo , Enfermedades del Sistema Nervioso Periférico , Animales , Axones/metabolismo , Adhesión Celular/genética , Moléculas de Adhesión Celular/genética , Moléculas de Adhesión Celular/metabolismo , Moléculas de Adhesión Celular Neuronal , Humanos , Ratones , Hipotonía Muscular/genética , Hipotonía Muscular/metabolismo , Espasticidad Muscular/metabolismo , Trastornos del Neurodesarrollo/genética , Trastornos del Neurodesarrollo/metabolismo , Pez Cebra/genética , Pez Cebra/metabolismoRESUMEN
Transportin-2 (TNPO2) mediates multiple pathways including non-classical nucleocytoplasmic shuttling of >60 cargoes, such as developmental and neuronal proteins. We identified 15 individuals carrying de novo coding variants in TNPO2 who presented with global developmental delay (GDD), dysmorphic features, ophthalmologic abnormalities, and neurological features. To assess the nature of these variants, functional studies were performed in Drosophila. We found that fly dTnpo (orthologous to TNPO2) is expressed in a subset of neurons. dTnpo is critical for neuronal maintenance and function as downregulating dTnpo in mature neurons using RNAi disrupts neuronal activity and survival. Altering the activity and expression of dTnpo using mutant alleles or RNAi causes developmental defects, including eye and wing deformities and lethality. These effects are dosage dependent as more severe phenotypes are associated with stronger dTnpo loss. Interestingly, similar phenotypes are observed with dTnpo upregulation and ectopic expression of TNPO2, showing that loss and gain of Transportin activity causes developmental defects. Further, proband-associated variants can cause more or less severe developmental abnormalities compared to wild-type TNPO2 when ectopically expressed. The impact of the variants tested seems to correlate with their position within the protein. Specifically, those that fall within the RAN binding domain cause more severe toxicity and those in the acidic loop are less toxic. Variants within the cargo binding domain show tissue-dependent effects. In summary, dTnpo is an essential gene in flies during development and in neurons. Further, proband-associated de novo variants within TNPO2 disrupt the function of the encoded protein. Hence, TNPO2 variants are causative for neurodevelopmental abnormalities.
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Discapacidades del Desarrollo/genética , Proteínas de Drosophila/genética , Enfermedades Hereditarias del Ojo/genética , Discapacidad Intelectual/genética , Carioferinas/genética , Anomalías Musculoesqueléticas/genética , beta Carioferinas/genética , Proteína de Unión al GTP ran/genética , Alelos , Secuencia de Aminoácidos , Animales , Discapacidades del Desarrollo/metabolismo , Discapacidades del Desarrollo/patología , Proteínas de Drosophila/antagonistas & inhibidores , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Enfermedades Hereditarias del Ojo/metabolismo , Enfermedades Hereditarias del Ojo/patología , Femenino , Dosificación de Gen , Regulación del Desarrollo de la Expresión Génica , Genoma Humano , Humanos , Lactante , Recién Nacido , Discapacidad Intelectual/metabolismo , Discapacidad Intelectual/patología , Carioferinas/antagonistas & inhibidores , Carioferinas/metabolismo , Masculino , Anomalías Musculoesqueléticas/metabolismo , Anomalías Musculoesqueléticas/patología , Mutación , Neuronas/metabolismo , Neuronas/patología , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Secuenciación Completa del Genoma , beta Carioferinas/metabolismo , Proteína de Unión al GTP ran/metabolismoRESUMEN
Focal segmental glomerulosclerosis (FSGS) is the main pathology underlying steroid-resistant nephrotic syndrome (SRNS) and a leading cause of chronic kidney disease. Monogenic forms of pediatric SRNS are predominantly caused by recessive mutations, while the contribution of de novo variants (DNVs) to this trait is poorly understood. Using exome sequencing (ES) in a proband with FSGS/SRNS, developmental delay, and epilepsy, we discovered a nonsense DNV in TRIM8, which encodes the E3 ubiquitin ligase tripartite motif containing 8. To establish whether TRIM8 variants represent a cause of FSGS, we aggregated exome/genome-sequencing data for 2,501 pediatric FSGS/SRNS-affected individuals and 48,556 control subjects, detecting eight heterozygous TRIM8 truncating variants in affected subjects but none in control subjects (p = 3.28 × 10-11). In all six cases with available parental DNA, we demonstrated de novo inheritance (p = 2.21 × 10-15). Reverse phenotyping revealed neurodevelopmental disease in all eight families. We next analyzed ES from 9,067 individuals with epilepsy, yielding three additional families with truncating TRIM8 variants. Clinical review revealed FSGS in all. All TRIM8 variants cause protein truncation clustering within the last exon between residues 390 and 487 of the 551 amino acid protein, indicating a correlation between this syndrome and loss of the TRIM8 C-terminal region. Wild-type TRIM8 overexpressed in immortalized human podocytes and neuronal cells localized to nuclear bodies, while constructs harboring patient-specific variants mislocalized diffusely to the nucleoplasm. Co-localization studies demonstrated that Gemini and Cajal bodies frequently abut a TRIM8 nuclear body. Truncating TRIM8 DNVs cause a neuro-renal syndrome via aberrant TRIM8 localization, implicating nuclear bodies in FSGS and developmental brain disease.
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Proteínas Portadoras/genética , Discapacidades del Desarrollo/genética , Epilepsia/genética , Glomeruloesclerosis Focal y Segmentaria/genética , Espacio Intranuclear/metabolismo , Síndrome Nefrótico/genética , Síndrome Nefrótico/metabolismo , Proteínas del Tejido Nervioso/genética , Adulto , Animales , Proteínas Portadoras/química , Proteínas Portadoras/metabolismo , Línea Celular , Niño , Preescolar , Codón sin Sentido , Discapacidades del Desarrollo/metabolismo , Epilepsia/metabolismo , Femenino , Glomeruloesclerosis Focal y Segmentaria/metabolismo , Humanos , Riñón/metabolismo , Masculino , Ratones , Mutación , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/metabolismo , Fenotipo , Podocitos/metabolismo , Secuenciación del ExomaRESUMEN
PURPOSE: Current and emerging treatments for Duchenne muscular dystrophy (DMD) position DMD as a candidate condition for newborn screening (NBS). In anticipation of the nomination of DMD for universal NBS, we conducted a prospective study under the Early Check voluntary NBS research program in North Carolina, United States. METHODS: We performed screening for creatine kinase-MM (CK-MM), a biomarker of muscle damage, on residual routine newborn dried blood spots (DBS) from participating newborns. Total creatine kinase testing and next generation sequencing of an 86-neuromuscular gene panel that included DMD were offered to parents of newborns who screened positive. Bivariate and multivariable analyses were performed to assess effects of biological and demographic predictors on CK-MM levels in DBS. RESULTS: We screened 13,354 newborns and identified 2 males with DMD. The provisional 1626 ng/mL cutoff was raised to 2032 ng/mL to improve specificity, and additional cutoffs (900 and 360 ng/mL) were implemented to improve sensitivity for older and low-birthweight newborns. CONCLUSION: Population-scale screening for elevated CK-MM in DBS is a feasible approach to identify newborns with DMD. Inclusion of birthweight- and age-specific cutoffs, repeat creatine kinase testing after 72 hours of age, and DMD sequencing improve sensitivity and specificity of screening.
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Distrofia Muscular de Duchenne , Masculino , Humanos , Recién Nacido , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/epidemiología , Distrofia Muscular de Duchenne/genética , Tamizaje Neonatal , Peso al Nacer , North Carolina/epidemiología , Estudios Prospectivos , Creatina QuinasaRESUMEN
Sphingolipids are a diverse family of lipids with critical structural and signalling functions in the mammalian nervous system, where they are abundant in myelin membranes. Serine palmitoyltransferase, the enzyme that catalyses the rate-limiting reaction of sphingolipid synthesis, is composed of multiple subunits including an activating subunit, SPTSSA. Sphingolipids are both essential and cytotoxic and their synthesis must therefore be tightly regulated. Key to the homeostatic regulation are the ORMDL proteins that are bound to serine palmitoyltransferase and mediate feedback inhibition of enzymatic activity when sphingolipid levels become excessive. Exome sequencing identified potential disease-causing variants in SPTSSA in three children presenting with a complex form of hereditary spastic paraplegia. The effect of these variants on the catalytic activity and homeostatic regulation of serine palmitoyltransferase was investigated in human embryonic kidney cells, patient fibroblasts and Drosophila. Our results showed that two different pathogenic variants in SPTSSA caused a hereditary spastic paraplegia resulting in progressive motor disturbance with variable sensorineural hearing loss and language/cognitive dysfunction in three individuals. The variants in SPTSSA impaired the negative regulation of serine palmitoyltransferase by ORMDLs leading to excessive sphingolipid synthesis based on biochemical studies and in vivo studies in Drosophila. These findings support the pathogenicity of the SPTSSA variants and point to excessive sphingolipid synthesis due to impaired homeostatic regulation of serine palmitoyltransferase as responsible for defects in early brain development and function.
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Paraplejía Espástica Hereditaria , Animales , Niño , Humanos , Paraplejía Espástica Hereditaria/genética , Serina C-Palmitoiltransferasa/genética , Serina C-Palmitoiltransferasa/metabolismo , Esfingolípidos/metabolismo , Membrana Celular/metabolismo , Mamíferos/metabolismoRESUMEN
PURPOSE: Next-generation sequencing (NGS) has revolutionized the diagnostic process for rare/ultrarare conditions. However, diagnosis rates differ between analytical pipelines. In the National Institutes of Health-Undiagnosed Diseases Network (UDN) study, each individual's NGS data are concurrently analyzed by the UDN sequencing core laboratory and the clinical sites. We examined the outcomes of this practice. METHODS: A retrospective review was performed at 2 UDN clinical sites to compare the variants and diagnoses/candidate genes identified with the dual analyses of the NGS data. RESULTS: In total, 95 individuals had 100 diagnoses/candidate genes. There was 59% concordance between the UDN sequencing core laboratories and the clinical sites in identifying diagnoses/candidate genes. The core laboratory provided more diagnoses, whereas the clinical sites prioritized more research variants/candidate genes (P < .001). The clinical sites solely identified 15% of the diagnoses/candidate genes. The differences between the 2 pipelines were more often because of variant prioritization disparities than variant detection. CONCLUSION: The unique dual analysis of NGS data in the UDN synergistically enhances outcomes. The core laboratory provided a clinical analysis with more diagnoses and the clinical sites prioritized more research variants/candidate genes. Implementing such concurrent dual analyses in other genomic research studies and clinical settings can improve both variant detection and prioritization.
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Enfermedades no Diagnosticadas , Estados Unidos/epidemiología , Humanos , Genómica , Enfermedades Raras/diagnóstico , Enfermedades Raras/genética , Secuenciación de Nucleótidos de Alto Rendimiento , LaboratoriosRESUMEN
PURPOSE: Mendelian etiologies for acute encephalopathies in previously healthy children are poorly understood, with the exception of RAN binding protein 2 (RANBP2)-associated acute necrotizing encephalopathy subtype 1 (ANE1). We provide clinical, genetic, and neuroradiological evidence that biallelic variants in ribonuclease inhibitor (RNH1) confer susceptibility to a distinctive ANE subtype. METHODS: This study aimed to evaluate clinical data, neuroradiological studies, genomic sequencing, and protein immunoblotting results in 8 children from 4 families who experienced acute febrile encephalopathy. RESULTS: All 8 healthy children became acutely encephalopathic during a viral/febrile illness and received a variety of immune modulation treatments. Long-term outcomes varied from death to severe neurologic deficits to normal outcomes. The neuroradiological findings overlapped with ANE but had distinguishing features. All affected children had biallelic predicted damaging variants in RNH1: a subset that was studied had undetectable RNH1 protein. Incomplete penetrance of the RNH1 variants was evident in 1 family. CONCLUSION: Biallelic variants in RNH1 confer susceptibility to a subtype of ANE (ANE2) in previously healthy children. Intensive immunological treatments may alter outcomes. Genomic sequencing in children with unexplained acute febrile encephalopathy can detect underlying genetic etiologies, such as RNH1, and improve outcomes in the probands and at-risk siblings.
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Encefalopatía Aguda Febril , Encefalopatías , Leucoencefalitis Hemorrágica Aguda , Niño , Humanos , Leucoencefalitis Hemorrágica Aguda/diagnóstico , Leucoencefalitis Hemorrágica Aguda/genética , Inflamasomas , Encefalopatías/genética , Factores de Transcripción , Ribonucleasas , Proteínas PortadorasRESUMEN
Early Check is a voluntary, large-scale expanded newborn screening study in North Carolina that uses a self-directed web-based portal for return of normal individual research results (IRR). Little is known about participant perspectives in using web-based portals to receive IRR. This study explored user attitudes and behaviors within the Early Check portal using three methods: (1) a feedback survey available to the consenting parent of participating infants (typically mothers), (2) semi-structured interviews conducted with a subset of parents, and (3) Google Analytics. During an approximate 3-year period, 17 936 newborns received normal IRR and there were 27 812 visits to the portal. Most surveyed parents reported viewing their baby's results (86%, 1410/1639). Parents largely found the portal easy to use to get results, and helpful in understanding the results. However, 10% of parents said it was difficult to find enough information to understand their baby's results. In Early Check, providing normal IRR via the portal made a large-scale study practical, and was highly rated by most users. Return of normal IRR may be particularly amenable to web-based portals, as the consequences to participants from not viewing results are modest, and the interpretation of a normal result is relatively straightforward.
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Madres , Padres , Lactante , Femenino , Humanos , Recién Nacido , Encuestas y Cuestionarios , Tamizaje Neonatal , InternetRESUMEN
Exome sequencing is a powerful tool in prenatal and postnatal genetics and can help identify novel candidate genes critical to human development. We describe seven unpublished probands with rare likely pathogenic variants or variants of uncertain significance that segregate with recessive disease in TBC1D32, including four fetal probands in three unrelated pedigrees and three pediatric probands in unrelated pedigrees. We also report clinical comparisons with seven previously published patients. Index probands were identified through an ongoing prenatal exome sequencing study and through an online data sharing platform (Gene Matcher™). A literature review was also completed. TBC1D32 is involved in the development and function of cilia and is expressed in the developing hypothalamus and pituitary gland. We provide additional data to expand the phenotype correlated with TBC1D32 variants, including a severe prenatal phenotype associated with life-limiting congenital anomalies.
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Ciliopatías , Embarazo , Femenino , Humanos , Niño , Fenotipo , Ciliopatías/diagnóstico , Ciliopatías/genética , Linaje , Proteínas Adaptadoras Transductoras de SeñalesRESUMEN
The endocannabinoid system is a highly conserved and ubiquitous signalling pathway with broad-ranging effects. Despite critical pathway functions, gene variants have not previously been conclusively linked to human disease. We identified nine children from eight families with heterozygous, de novo truncating variants in the last exon of DAGLA with a neuro-ocular phenotype characterized by developmental delay, ataxia and complex oculomotor abnormality. All children displayed paroxysms of nystagmus or eye deviation accompanied by compensatory head posture and worsened incoordination most frequently after waking. RNA sequencing showed clear expression of the truncated transcript and no differences were found between mutant and wild-type DAGLA activity. Immunofluorescence staining of patient-derived fibroblasts and HEK cells expressing the mutant protein showed distinct perinuclear aggregation not detected in control samples. This report establishes truncating variants in the last DAGLA exon as the cause of a unique paediatric syndrome. Because enzymatic activity was preserved, the observed mislocalization of the truncated protein may account for the observed phenotype. Potential mechanisms include DAGLA haploinsufficiency at the plasma membrane or dominant negative effect. To our knowledge, this is the first report directly linking an endocannabinoid system component with human genetic disease and sets the stage for potential future therapeutic avenues.
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Endocannabinoides , Enfermedades del Sistema Nervioso , Humanos , Niño , Fenotipo , Enfermedades del Sistema Nervioso/genética , Heterocigoto , Síndrome , Proteínas MutantesRESUMEN
PURPOSE: Haploinsufficiency of PSMD12 has been reported in individuals with neurodevelopmental phenotypes, including developmental delay/intellectual disability (DD/ID), facial dysmorphism, and congenital malformations, defined as Stankiewicz-Isidor syndrome (STISS). Investigations showed that pathogenic variants in PSMD12 perturb intracellular protein homeostasis. Our objective was to further explore the clinical and molecular phenotypic spectrum of STISS. METHODS: We report 24 additional unrelated patients with STISS with various truncating single nucleotide variants or copy-number variant deletions involving PSMD12. We explore disease etiology by assessing patient cells and CRISPR/Cas9-engineered cell clones for various cellular pathways and inflammatory status. RESULTS: The expressivity of most clinical features in STISS is highly variable. In addition to previously reported DD/ID, speech delay, cardiac and renal anomalies, we also confirmed preaxial hand abnormalities as a feature of this syndrome. Of note, 2 patients also showed chilblains resembling signs observed in interferonopathy. Remarkably, our data show that STISS patient cells exhibit a profound remodeling of the mTORC1 and mitophagy pathways with an induction of type I interferon-stimulated genes. CONCLUSION: We refine the phenotype of STISS and show that it can be clinically recognizable and biochemically diagnosed by a type I interferon gene signature.
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Discapacidad Intelectual , Trastornos del Desarrollo del Lenguaje , Anomalías Musculoesqueléticas , Haploinsuficiencia , Humanos , Discapacidad Intelectual/diagnóstico , Trastornos del Desarrollo del Lenguaje/genética , Anomalías Musculoesqueléticas/genética , FenotipoRESUMEN
The Genome Empowerment Scale (GEmS), developed as a research tool, assesses perspectives of parents of children with undiagnosed disorders about to undergo exome or genome sequencing related to the process of empowerment. We defined genomic healthcare empowerment as follows: perceived ability to understand and seek new information related to the genomic sequencing, manage emotions related to the diagnostic process and outcomes, and utilize genomic sequencing information to the betterment of the individual/child and family. The GEmS consists of four scales, two are primarily emotion-focused (Meaning of a Diagnosis, and Emotional Management of the Process) and two are action-oriented (Seeking Information and Support, and Implications and Planning). The purpose of this research was to provide a strategy for interpreting results from the GEmS and present illustrative cases. These illustrations should serve to facilitate use of the GEmS in the clinical and research arena, particularly with respect to guiding genetic counseling processes for parents of children with undiagnosed conditions.
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Genómica , Padres , Niño , Atención a la Salud , Familia , Humanos , Padres/psicología , Secuenciación del ExomaRESUMEN
Located in the critical 1p36 microdeletion region, the chromodomain helicase DNA-binding protein 5 (CHD5) gene encodes a subunit of the nucleosome remodeling and deacetylation (NuRD) complex required for neuronal development. Pathogenic variants in six of nine chromodomain (CHD) genes cause autosomal dominant neurodevelopmental disorders, while CHD5-related disorders are still unknown. Thanks to GeneMatcher and international collaborations, we assembled a cohort of 16 unrelated individuals harboring heterozygous CHD5 variants, all identified by exome sequencing. Twelve patients had de novo CHD5 variants, including ten missense and two splice site variants. Three familial cases had nonsense or missense variants segregating with speech delay, learning disabilities, and/or craniosynostosis. One patient carried a frameshift variant of unknown inheritance due to unavailability of the father. The most common clinical features included language deficits (81%), behavioral symptoms (69%), intellectual disability (64%), epilepsy (62%), and motor delay (56%). Epilepsy types were variable, with West syndrome observed in three patients, generalized tonic-clonic seizures in two, and other subtypes observed in one individual each. Our findings suggest that, in line with other CHD-related disorders, heterozygous CHD5 variants are associated with a variable neurodevelopmental syndrome that includes intellectual disability with speech delay, epilepsy, and behavioral problems as main features.
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ADN Helicasas/genética , Discapacidad Intelectual/genética , Mutación Missense , Proteínas del Tejido Nervioso/genética , Trastornos del Neurodesarrollo/genética , Adolescente , Dominio Catalítico , Niño , Preescolar , Estudios de Cohortes , Epilepsia/genética , Femenino , Genes Dominantes , Humanos , Discapacidad Intelectual/fisiopatología , Masculino , Trastornos del Neurodesarrollo/fisiopatología , Linaje , Adulto JovenRESUMEN
PURPOSE: The NIH Undiagnosed Diseases Network (UDN) evaluates participants with disorders that have defied diagnosis, applying personalized clinical and genomic evaluations and innovative research. The clinical sites of the UDN are essential to advancing the UDN mission; this study assesses their contributions relative to standard clinical practices. METHODS: We analyzed retrospective data from four UDN clinical sites, from July 2015 to September 2019, for diagnoses, new disease gene discoveries and the underlying investigative methods. RESULTS: Of 791 evaluated individuals, 231 received 240 diagnoses and 17 new disease-gene associations were recognized. Straightforward diagnoses on UDN exome and genome sequencing occurred in 35% (84/240). We considered these tractable in standard clinical practice, although genome sequencing is not yet widely available clinically. The majority (156/240, 65%) required additional UDN-driven investigations, including 90 diagnoses that occurred after prior nondiagnostic exome sequencing and 45 diagnoses (19%) that were nongenetic. The UDN-driven investigations included complementary/supplementary phenotyping, innovative analyses of genomic variants, and collaborative science for functional assays and animal modeling. CONCLUSION: Investigations driven by the clinical sites identified diagnostic and research paradigms that surpass standard diagnostic processes. The new diagnoses, disease gene discoveries, and delineation of novel disorders represent a model for genomic medicine and science.
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Enfermedades no Diagnosticadas , Animales , Genómica , Humanos , Enfermedades Raras/diagnóstico , Enfermedades Raras/genética , Estudios Retrospectivos , Secuenciación del ExomaRESUMEN
In pleiotropic diseases, multiple organ systems are affected causing a variety of clinical manifestations. Here, we report a pleiotropic disorder with a unique constellation of neurological, endocrine, exocrine, and haematological findings that is caused by biallelic MADD variants. MADD, the mitogen-activated protein kinase (MAPK) activating death domain protein, regulates various cellular functions, such as vesicle trafficking, activity of the Rab3 and Rab27 small GTPases, tumour necrosis factor-α (TNF-α)-induced signalling and prevention of cell death. Through national collaboration and GeneMatcher, we collected 23 patients with 21 different pathogenic MADD variants identified by next-generation sequencing. We clinically evaluated the series of patients and categorized the phenotypes in two groups. Group 1 consists of 14 patients with severe developmental delay, endo- and exocrine dysfunction, impairment of the sensory and autonomic nervous system, and haematological anomalies. The clinical course during the first years of life can be potentially fatal. The nine patients in Group 2 have a predominant neurological phenotype comprising mild-to-severe developmental delay, hypotonia, speech impairment, and seizures. Analysis of mRNA revealed multiple aberrant MADD transcripts in two patient-derived fibroblast cell lines. Relative quantification of MADD mRNA and protein in fibroblasts of five affected individuals showed a drastic reduction or loss of MADD. We conducted functional tests to determine the impact of the variants on different pathways. Treatment of patient-derived fibroblasts with TNF-α resulted in reduced phosphorylation of the extracellular signal-regulated kinases 1 and 2, enhanced activation of the pro-apoptotic enzymes caspase-3 and -7 and increased apoptosis compared to control cells. We analysed internalization of epidermal growth factor in patient cells and identified a defect in endocytosis of epidermal growth factor. We conclude that MADD deficiency underlies multiple cellular defects that can be attributed to alterations of TNF-α-dependent signalling pathways and defects in vesicular trafficking. Our data highlight the multifaceted role of MADD as a signalling molecule in different organs and reveal its physiological role in regulating the function of the sensory and autonomic nervous system and endo- and exocrine glands.
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Proteínas Adaptadoras de Señalización del Receptor del Dominio de Muerte/genética , Discapacidades del Desarrollo/genética , Factores de Intercambio de Guanina Nucleótido/genética , Enfermedades del Sistema Nervioso/genética , Humanos , Mutación , Fenotipo , Transporte de Proteínas/genética , Transducción de Señal/genéticaRESUMEN
Hereditary spastic paraplegia (HSP) is a group of disorders with predominant symptoms of lower-extremity weakness and spasticity. Despite the delineation of numerous genetic causes of HSP, a significant portion of individuals with HSP remain molecularly undiagnosed. Through exome sequencing, we identified five unrelated families with childhood-onset nonsyndromic HSP, all presenting with progressive spastic gait, leg clonus, and toe walking starting from 7 to 8 years old. A recurrent two-base pair deletion (c.426_427delGA, p.K143Sfs*15) in the UBAP1 gene was found in four families, and a similar variant (c.475_476delTT, p.F159*) was detected in a fifth family. The variant was confirmed to be de novo in two families and inherited from an affected parent in two other families. RNA studies performed in lymphocytes from one patient with the de novo c.426_427delGA variant demonstrated escape of nonsense-mediated decay of the UBAP1 mutant transcript, suggesting the generation of a truncated protein. Both variants identified in this study are predicted to result in truncated proteins losing the capacity of binding to ubiquitinated proteins, hence appearing to exhibit a dominant-negative effect on the normal function of the endosome-specific endosomal sorting complexes required for the transport-I complex.
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Proteínas Portadoras/genética , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Mutación , Paraplejía Espástica Hereditaria/diagnóstico , Paraplejía Espástica Hereditaria/genética , Edad de Inicio , Niño , Femenino , Estudios de Asociación Genética/métodos , Sitios Genéticos , Humanos , Linfocitos/inmunología , Linfocitos/metabolismo , Masculino , Linaje , Fenotipo , Secuenciación del ExomaRESUMEN
PURPOSE: Sixty to seventy-five percent of individuals with rare and undiagnosed phenotypes remain undiagnosed after exome sequencing (ES). With standard ES reanalysis resolving 10-15% of the ES negatives, further approaches are necessary to maximize diagnoses in these individuals. METHODS: In 38 ES negative patients an individualized genomic-phenotypic approach was employed utilizing (1) phenotyping; (2) reanalyses of FASTQ files, with innovative bioinformatics; (3) targeted molecular testing; (4) genome sequencing (GS); and (5) conferring of clinical diagnoses when pathognomonic clinical findings occurred. RESULTS: Certain and highly likely diagnoses were made in 18/38 (47%) individuals, including identifying two new developmental disorders. The majority of diagnoses (>70%) were due to our bioinformatics, phenotyping, and targeted testing identifying variants that were undetected or not prioritized on prior ES. GS diagnosed 3/18 individuals with structural variants not amenable to ES. Additionally, tentative diagnoses were made in 3 (8%), and in 5 individuals (13%) candidate genes were identified. Overall, diagnoses/potential leads were identified in 26/38 (68%). CONCLUSIONS: Our comprehensive approach to ES negatives maximizes the ES and clinical data for both diagnoses and candidate gene identification, without GS in the majority. This iterative approach is cost-effective and is pertinent to the current conundrum of ES negatives.
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Discapacidades del Desarrollo/diagnóstico , Discapacidades del Desarrollo/genética , Exoma/genética , Predisposición Genética a la Enfermedad , Niño , Discapacidades del Desarrollo/epidemiología , Femenino , Genómica , Humanos , Masculino , Fenotipo , Análisis de Secuencia de ADN , Secuenciación del Exoma/métodos , Secuenciación Completa del GenomaRESUMEN
PURPOSE: Diagnosing monogenic diseases facilitates optimal care, but can involve the manual evaluation of hundreds of genetic variants per case. Computational tools like Phrank expedite this process by ranking all candidate genes by their ability to explain the patient's phenotypes. To use these tools, busy clinicians must manually encode patient phenotypes from lengthy clinical notes. With 100 million human genomes estimated to be sequenced by 2025, a fast alternative to manual phenotype extraction from clinical notes will become necessary. METHODS: We introduce ClinPhen, a fast, high-accuracy tool that automatically converts clinical notes into a prioritized list of patient phenotypes using Human Phenotype Ontology (HPO) terms. RESULTS: ClinPhen shows superior accuracy and 20× speedup over existing phenotype extractors, and its novel phenotype prioritization scheme improves the performance of gene-ranking tools. CONCLUSION: While a dedicated clinician can process 200 patient records in a 40-hour workweek, ClinPhen does the same in 10 minutes. Compared with manual phenotype extraction, ClinPhen saves an additional 3-5 hours per Mendelian disease diagnosis. Providers can now add ClinPhen's output to each summary note attached to a filled testing laboratory request form. ClinPhen makes a substantial contribution to improvements in efficiency critically needed to meet the surging demand for clinical diagnostic sequencing.
Asunto(s)
Biología Computacional , Enfermedades Genéticas Congénitas/diagnóstico , Registros Médicos , Algoritmos , Humanos , Procesamiento de Lenguaje Natural , FenotipoRESUMEN
BACKGROUND: Individuals with late-onset Pompe disease (LOPD) and the common c.-32-13â¯Tâ¯>â¯G variant are widely thought to have milder, adult-onset disease. This belief, and the consequent low suspicion of clinical involvement in children, has led to delays in diagnosis and treatment initiation in patients with early onset of symptoms. Previous reports of LOPD in children do not include description of the early-onset phenotype. This description of signs and symptoms, some of which are subtle and less known, is important to facilitate prompt identification and appropriate treatment in symptomatic children. METHODS: Retrospective chart review of a cohort of 84 LOPD patients with the c.-32-13â¯Tâ¯>â¯G variant was conducted to identify patients diagnosed clinically (as opposed to through newborn screening) who had clinically documented symptom-onset within the first two years of life. RESULTS: Four patients had early onset of symptoms, with age at onset ranging from 10â¯days to 20â¯months. Initial symptoms included delay in achievement of gross motor milestones, signs of proximal muscle weakness, swallow and feeding difficulties, and sleep apnea. Early and characteristic alterations in posture and movement were identified in all patients. Age at diagnosis ranged from 10â¯months to 26â¯months. Median age at enzyme replacement therapy (ERT) initiation was 23.5â¯months. Despite ERT, progression of musculoskeletal involvement and residual muscle weakness was evident in all patients, as evidenced by ptosis, myopathic facies, scoliosis, lumbar lordosis, scapular winging, and trunk and lower extremity weakness. Standardized functional assessments showed gross motor function below age level as measured by the Alberta Infant Motor Scales, the Peabody Developmental Motor Scales-2, the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition, and the six-minute walk test. CONCLUSIONS: Onset of symptoms including delay in achievement of gross motor milestones, signs of proximal muscle weakness, swallow and feeding difficulties, and sleep apnea in the first two years of life is not uncommon in individuals with LOPD and the c.-32-13â¯Tâ¯>â¯G variant. Patients with early-onset disease appear to have a more, rapid and severe progression of disease with persistent residual muscle deficits which partially improve with higher doses of ERT. Careful evaluation for specific and characteristic patterns of posture and movement in patients with this variant is necessary to identify those who have early onset of disease. Increased awareness of the early-onset signs and symptoms may also enable early identification of disease onset in children who are diagnosed through newborn screening.
Asunto(s)
Variación Genética , Enfermedad del Almacenamiento de Glucógeno Tipo II/diagnóstico , Enfermedad del Almacenamiento de Glucógeno Tipo II/genética , alfa-Glucosidasas/genética , Terapia de Reemplazo Enzimático , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Fenotipo , Estudios Retrospectivos , Factores de TiempoRESUMEN
While genomic sequencing (ES/GS) has the potential to diagnose children with difficult to diagnose phenotypes, the goal should be not only a diagnosis, but also to empower parents to seek next steps for their children and to emotionally manage the outcome, whether or not a diagnosis is secured. To help achieve this goal, objective measures are needed to assess the process of parental empowerment related to genome sequencing. We present the validity and reliability of the Genome Empowerment Scale (GEmS), developed using a healthcare empowerment theoretical model. To evaluate its psychometric properties, 158 parents of 117 children with an undiagnosed condition undergoing genomic sequencing completed the GEmS, measures for criterion validity and for depression and anxiety. Factor analysis resulted in a four factor solution: (a) meaning of a diagnosis; (b) emotional management of the process; (c) seeking information and support and (d) implications and planning. Reliability and validity analyses show that the GEmS has good psychometric properties. The inter-relationships among the factors revealed a profile that may identify parents at risk for a poorer outcome who may benefit from targeted genetic counseling. The GEmS, an objective measure of parental genomic empowerment, can be utilized for future research and translational applications.