Objective: Neurofibromatosis Type 1 (NF1) is a genetic syndrome that affects cognitive, behavioral, and social development. Nonliteral language (NLL) comprehension has not been examined in children ...with NF1. This study examined NLL comprehension in children with NF1 and associated neuropsychological correlates. Method: NLL comprehension was examined in children with NF1 (n = 49) and typically developing (TD) controls (n = 27) aged 4-12 years using a novel NLL task. The task assessed comprehension of sarcasm, metaphor, simile, and literal language. Cognitive (Wechsler Scales Composites or the Woodcock-Johnson Test of Cognitive Abilities Revised scaled scores) and behavioral (attention deficit hyperactivity disorder ADHD symptoms) correlates of NLL comprehension in children with NF1 were also examined. Results: Children with NF1 demonstrated significantly poorer sarcasm comprehension than TD children and a vulnerability in metaphor comprehension. Simile and literal language comprehension were not significantly different between groups. Working memory difficulties and impulsive/hyperactive ADHD symptoms were associated with a reduced ability to identify sarcasm in NF1, while verbal comprehension, fluid reasoning, and inattentive ADHD symptoms were not. Conclusions: Results suggest children with NF1 experience challenges in understanding complex NLL comprehension, which are related to reduced working memory and increased impulsivity/hyperactivity. This study provides an initial insight into the figurative language abilities of children with NF1, which should be examined in relation to their social difficulties in future studies.
Key Points
Question: Are nonliteral language skills impacted in children with neurofibromatosis Type 1? Findings: Children with neurofibromatosis Type 1 demonstrate poorer sarcasm comprehension and a relative weakness in metaphor comprehension. Importance: Figurative language difficulties in children with neurofibromatosis Type 1 may contribute to difficulties in social and everyday functioning. Next Steps: Future studies should examine how nonliteral language difficulties in children with neurofibromatosis Type 1 relate to their social difficulties and co-occurring autism spectrum disorder.
Approach to the diagnosis of congenital myopathies North, Kathryn N; Wang, Ching H; Clarke, Nigel ...
Neuromuscular disorders : NMD,
02/2014, Letnik:
24, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Abstract Over the past decade there have been major advances in defining the genetic basis of the majority of congenital myopathy subtypes. However the relationship between each congenital myopathy, ...defined on histological grounds, and the genetic cause is complex. Many of the congenital myopathies are due to mutations in more than one gene, and mutations in the same gene can cause different muscle pathologies. The International Standard of Care Committee for Congenital Myopathies performed a literature review and consulted a group of experts in the field to develop a summary of (1) the key features common to all forms of congenital myopathy and (2) the specific features that help to discriminate between the different genetic subtypes. The consensus statement was refined by two rounds of on-line survey, and a three-day workshop. This consensus statement provides guidelines to the physician assessing the infant or child with hypotonia and weakness. We summarise the clinical features that are most suggestive of a congenital myopathy, the major differential diagnoses and the features on clinical examination, investigations, muscle pathology and muscle imaging that are suggestive of a specific genetic diagnosis to assist in prioritisation of genetic testing of known genes. As next generation sequencing becomes increasingly used as a diagnostic tool in clinical practise, these guidelines will assist in determining which sequence variations are likely to be pathogenic.
Duchenne muscular dystrophy is caused by the absence of the protein dystrophin from skeletal muscle and is characterized by progressive cycles of necrosis/regeneration. Using the dystrophin deficient
...mouse model, we studied the morphological and contractile chronology of dystrophic skeletal muscle pathology in fast-twitch Extensor Digitorum Longus muscles from animals 4-22 months of age containing 100% regenerated muscle fibers. Catastrophically, the older age groups lost ∼80% of their maximum force after one eccentric contraction (EC) of 20% strain with the greatest loss of ∼92% recorded in senescent 22-month-old
mice. In old age groups, there was minimal force recovery ∼24% after 120 min, correlated with a dramatic increase in the number and complexity of branched fibers. This data supports our two-phase model where a "tipping point" is reached when branched fibers rupture irrevocably on EC. These findings have important implications for pre-clinical drug studies and genetic rescue strategies.
In light of the proliferation of recent research into social function in neurofibromatosis type 1 (NF1), a systematic review and meta-analysis is required to synthesise data and place findings within ...the context of a theoretical framework. This paper reviews findings from research into social function and autism spectrum disorder (ASD) in children and adults with NF1 and integrates these findings with the Socio-Cognitive Integration Abilities Model (SOCIAL). It also critically appraises links between social outcomes, internal and external factors moderating social functioning, cognitive domains implicated in social functioning, and underlying neural pathology in NF1. A systematic literature search conducted in MedLine (Ovid), PsycINFO (Ovid), Embase (Ovid), and PubMed electronic databases yielded 35 papers that met inclusion criteria for the systematic review. Out of these papers, 22 papers provided sufficient data for meta-analysis. Findings from this review and meta-analysis provide evidence that children and adults with NF1 exhibit significantly higher prevalence and severity of social dysfunction and ASD symptomatology. To date, very few studies have examined social cognition in NF1 but results indicate the presence of both perceptual and higher-level impairments in this population. The results of this review also provide support for age, gender, and comorbid ADHD as moderating factors for social outcomes in NF1. Suggestions for future research are offered to further our understanding of the social phenotype in NF1 and to facilitate the development of targeted interventions.
The ferlin gene family possesses a rare and identifying feature consisting of multiple tandem C2 domains and a C-terminal transmembrane domain. Much currently remains unknown about the fundamental ...function of this gene family, however, mutations in its two most well-characterised members, dysferlin and otoferlin, have been implicated in human disease. The availability of genome sequences from a wide range of species makes it possible to explore the evolution of the ferlin family, providing contextual insight into characteristic features that define the ferlin gene family in its present form in humans.
Ferlin genes were detected from all species of representative phyla, with two ferlin subgroups partitioned within the ferlin phylogenetic tree based on the presence or absence of a DysF domain. Invertebrates generally possessed two ferlin genes (one with DysF and one without), with six ferlin genes in most vertebrates (three DysF, three non-DysF). Expansion of the ferlin gene family is evident between the divergence of lamprey (jawless vertebrates) and shark (cartilaginous fish). Common to almost all ferlins is an N-terminal C2-FerI-C2 sandwich, a FerB motif, and two C-terminal C2 domains (C2E and C2F) adjacent to the transmembrane domain. Preservation of these structural elements throughout eukaryotic evolution suggests a fundamental role of these motifs for ferlin function. In contrast, DysF, C2DE, and FerA are optional, giving rise to subtle differences in domain topologies of ferlin genes. Despite conservation of multiple C2 domains in all ferlins, the C-terminal C2 domains (C2E and C2F) displayed higher sequence conservation and greater conservation of putative calcium binding residues across paralogs and orthologs. Interestingly, the two most studied non-mammalian ferlins (Fer-1 and Misfire) in model organisms C. elegans and D. melanogaster, present as outgroups in the phylogenetic analysis, with results suggesting reproduction-related divergence and specialization of species-specific functions within their genus.
Our phylogenetic studies provide evolutionary insight into the ferlin gene family. We highlight the existence of ferlin-like proteins throughout eukaryotic evolution, from unicellular phytoplankton and apicomplexan parasites, through to humans. We characterise the preservation of ferlin structural motifs, not only of C2 domains, but also the more poorly characterised ferlin-specific motifs representing the DysF, FerA and FerB domains. Our data suggest an ancient role of ferlin proteins, with lessons from vertebrate biology and human disease suggesting a role relating to vesicle fusion and plasma membrane specialization.
Clinical validity assessments of gene-disease associations underpin analysis and reporting in diagnostic genomics, and yet wide variability exists in practice, particularly in use of these ...assessments for virtual gene panel design and maintenance. Harmonization efforts are hampered by the lack of agreed terminology, agreed gene curation standards, and platforms that can be used to identify and resolve discrepancies at scale. We undertook a systematic comparison of the content of 80 virtual gene panels used in two healthcare systems by multiple diagnostic providers in the United Kingdom and Australia. The process was enabled by a shared curation platform, PanelApp, and resulted in the identification and review of 2,144 discordant gene ratings, demonstrating the utility of sharing structured gene-disease validity assessments and collaborative discordance resolution in establishing national and international consensus.
Clinical validity assessments of gene-disease associations underpin analysis and reporting in diagnostic genomics, and yet wide variability exists in practice, particularly in use of these assessments for virtual gene panel design and maintenance. Harmonization efforts are hampered by the lack of agreed terminology, agreed gene curation standards, and platforms that can be used to identify and resolve discrepancies at scale. We undertook a systematic comparison of the content of 80 virtual gene panels used in two healthcare systems by multiple diagnostic providers in the United Kingdom and Australia. The process was enabled by a shared curation platform, PanelApp, and resulted in the identification and review of 2,144 discordant gene ratings, demonstrating the utility of sharing structured gene-disease validity assessments and collaborative discordance resolution in establishing national and international consensus.
A common null polymorphism in the ACTN3 gene (rs1815739:C>T) results in replacement of an arginine (R) with a premature stop codon (X) at amino acid 577 in the fast muscle protein α‐actinin‐3. The ...ACTN3 p.Arg577Ter allele (aka p.R577* or R577X) has undergone positive selection, with an increase in the X allele frequency as modern humans migrated out of Africa into the colder, less species‐rich Eurasian climates suggesting that the absence of α‐actinin‐3 may be beneficial in these conditions. Approximately 1.5 billion people worldwide are completely deficient in α‐actinin‐3. While the absence of α‐actinin‐3 influences skeletal muscle function and metabolism this does not result in overt muscle disease. α‐Actinin‐3 deficiency (ACTN3 XX genotype) is constantly underrepresented in sprint/power performance athletes. However, recent findings from our group and others suggest that the ACTN3 R577X genotype plays a role beyond athletic performance with effects observed in ageing, bone health, and inherited muscle disorders such as McArdle disease and Duchenne muscle dystrophy. In this review, we provide an update on the current knowledge regarding the influence of ACTN3 R577X on skeletal muscle function and its potential biological and clinical implications. We also outline future research directions to explore the role of α‐actinin‐3 in healthy and diseased populations.
A null polymorphism in the ACTN3 gene (rs1815739:C>T) results in a premature stop codon (X) at amino acid 577 in the fast muscle protein α‐actinin‐3. Positive selection for the X‐allele occurred as modern humans migrated out of Africa (Figure 2). Homozygosity for the X‐allele results in the absence of α‐actinin‐3 in 1.5 billion people worldwide. While not causing disease, the absence of α‐actinin‐3 may be detrimental to sprint performance and plays a role in ageing, bone health and inherited muscle diseases.
We used gene editing to introduce DNA sequences encoding the tdTomato fluorescent protein into the α -skeletal actin 1 (ACTA1) locus to develop an ACTA1-tdTomato induced pluripotent stem cell ...reporter line for monitoring differentiation of skeletal muscle. This cell line will be used to better understand skeletal muscle maturation and development in vitro as well as provide a useful tool for drug screening and the evaluation of novel therapeutics for the treatment of skeletal muscle disease.
α-Actinin-3 deficiency occurs in approximately 16% of the global population due to homozygosity for a common nonsense polymorphism in the ACTN3 gene. Loss of α-actinin-3 is associated with reduced ...power and enhanced endurance capacity in elite athletes and nonathletes due to "slowing" of the metabolic and physiological properties of fast fibers. Here, we have shown that α-actinin-3 deficiency results in increased calcineurin activity in mouse and human skeletal muscle and enhanced adaptive response to endurance training. α-Actinin-2, which is differentially expressed in α-actinin-3-deficient muscle, has higher binding affinity for calsarcin-2, a key inhibitor of calcineurin activation. We have further demonstrated that α-actinin-2 competes with calcineurin for binding to calsarcin-2, resulting in enhanced calcineurin signaling and reprogramming of the metabolic phenotype of fast muscle fibers. Our data provide a mechanistic explanation for the effects of the ACTN3 genotype on skeletal muscle performance in elite athletes and on adaptation to changing physical demands in the general population. In addition, we have demonstrated that the sarcomeric α-actinins play a role in the regulation of calcineurin signaling.
More than a billion humans worldwide are predicted to be completely deficient in the fast skeletal muscle fiber protein α-actinin-3 owing to homozygosity for a premature stop codon polymorphism, ...R577X, in the ACTN3 gene. The R577X polymorphism is associated with elite athlete status and human muscle performance, suggesting that α-actinin-3 deficiency influences the function of fast muscle fibers. Here we show that loss of α-actinin-3 expression in a knockout mouse model results in a shift in muscle metabolism toward the more efficient aerobic pathway and an increase in intrinsic endurance performance. In addition, we demonstrate that the genomic region surrounding the 577X null allele shows low levels of genetic variation and recombination in individuals of European and East Asian descent, consistent with strong, recent positive selection. We propose that the 577X allele has been positively selected in some human populations owing to its effect on skeletal muscle metabolism.
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