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α-Actinin-3 is primarily expressed in fast (Type II) fibers in the human skeletal muscle. Over 70% of the global population has at least one copy of a loss of function allele because of a premature stop codon in the ACTN3 gene (R577X). Homozygosity for this variant (577XX) occurs in approximately 16% of humans worldwide and results in complete α-actinin-3 deficiency, which is detrimental to sprint/power performance and alters adaptation to changing physical demands. The functional implications of α-actinin-3 deficiency have been the subject of over 90 studies; however, the effect of heterozygosity for the ACTN3 null allele is not well documented or understood. PURPOSE: We reviewed the literature to focus on the most common ACTN3 genotype (577RX) and its effect on human muscle performance. Specifically, we aimed to determine whether the ACTN3 X allele exerts its effect on human performance only when two copies are present (i.e., in an autosomal recessive fashion). RESULTS: Across a spectrum of conditions, three genotype models (additive, dominant, and recessive) were reported. Most studies assessing healthy adults demonstrated that 577RX heterozygotes performed intermediately (additive model) and/or similarly to the RR genotypes (recessive model). Other studies, (aging, disease/injury, elite sprint performance) showed no definitive genetic model. CONCLUSIONS: Assessment of the biological link between dosage, regulation, and function for each ACTN3 genotype is required to improve our understanding of its functional effect and biological penetrance in healthy, aging, and disease populations. [ABSTRACT FROM AUTHOR]

The extremes of exercise capacity and health are considered a complex interplay between genes and the environment. In general, the study of animal models has proven critical for deep mechanistic exploration that provides guidance for focused and hypothesisdriven discovery in humans. Hypotheses underlying molecular mechanisms of disease and gene/tissue function can be tested in rodents to generate sufficient evidence to resolve and progress our understanding of human biology. Here we provide examples of three alternative uses of rodent models that have been applied successfully to advance knowledge that bridges our understanding of the connection between exercise capacity and health status. First we review the strong association between exercise capacity and all-cause morbidity and mortality in humans through artificial selection on low and high exercise performance in the rat and the consequent generation of the "energy transfer hypothesis." Second we review specific transgenic and knockout mouse models that replicate the human disease condition and performance. This includes human glycogen storage diseases (McArdle and Pompe) and α-actinin-3 deficiency. Together these rodent models provide an overview of the advancements of molecular knowledge required for clinical translation. Continued study of these models in conjunction with human association studies will be critical to resolving the complex gene-environment interplay linking exercise capacity, health, and disease. [ABSTRACT FROM AUTHOR]

Aim To investigate if children with neurofibromatosis type 1 ( NF1) have reduced muscle strength compared with children with typical development. Method Maximal isometric strength of 15 upper and lower limb muscle groups was evaluated in 30 children with NF1 (16 males, 14 females; aged 4-16y) and 30 age-, sex-, height-, and weight-matched controls using hand-held dynamometry by a single evaluator. Both the left and right sides were assessed. Results Children with NF1 were significantly weaker than children with typical development across all 15 muscle groups assessed ( p<0.05). Apart from elbow flexion, there were no differences between the left and right sides ( p>0.05). Magnitude of differences between the children with NF1 compared with the controls ranged from 3% to 43%. Males and females were equally affected. Interpretation This study shows that children with NF1 have reduced muscle strength compared with children with typical development. This muscle weakness is present from the earliest stages of the disease assessed and persists throughout childhood with no sex difference. These results support recent evidence from mouse studies that NF1 is associated with a primary myopathy. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]

Muscle weakness in childhood can be caused by a lesion at any point extending from the motor cortex, brainstem and spinal cord to the anterior horn cell, peripheral nerve, neuromuscular junction and muscle. A comprehensive history and physical examination is essential to aid classification of the neuromuscular disorder and direct gene testing. The more common disorders such as spinal muscular atrophy, Duchenne muscular dystrophy, myotonic dystrophy and facioscapulohumeral dystrophy may be diagnosed on direct gene testing based on the history and clinical examination. The congenital myopathies are classified based on structural abnormalities on muscle biopsy, while protein abnormalities on immunohistochemistry and immunoblotting aid classification of the muscular dystrophies. In this review, we provide an approach to diagnosis of a child with weakness, with a focus on the inherited neuromuscular disorders, and the features on history, examination and investigation that help to distinguish between them. [ABSTRACT FROM AUTHOR]

A common polymorphism (R577X) in the ACTN3 gene results in complete deficiency of ⍺-actinin-3 protein in ~16% of humans worldwide. The presence of ⍺-actinin-3 protein is associated with improved sprint/power performance in athletes and the general population. Despite this, there is evidence that the null genotype XX has been acted on by recent positive selection, likely due to its emerging role in the regulation of muscle metabolism. ⍺-Actinin-3 deficiency reduces the activity of glycogen phosphorylase and results in a fundamental shift toward more oxidative pathways of energy utilization. [ABSTRACT FROM AUTHOR]

Abstract: Biological sensors and their ability to detect and respond to change in the cellular environment can be modulated by protein scaffolds acting within their interaction network. The skeletal muscle α-actinins have been considered as primarily structural scaffold proteins. However, deficiency of α-actinin-3 due to a common null polymorphism results in predominantly metabolic changes in skeletal muscle function. In this review, we explore the range of phenotypes associated with α-actinin-3 deficiency, and draw supporting evidence from known interaction partners for its role as a scaffold which acts to modulate biological sensors that result in changes in muscle metabolism and structure. [Copyright &y& Elsevier]

Discusses the study on the evolution and function of α-actinin-3 ancient family of actin-binding proteins. Investigation of the association between R577X genotype with performance in a variety of athletic endeavors; Exploration on the function and evolutionary history of the ACTN3 gene; Evolution of protein function.

Atypical habituation to repetitive information has been commonly reported in Autism Spectrum Disorder (ASD) but it is not yet clear whether similar abnormalities are present in Neurofibromatosis Type 1 (NF1). We employed a cross-syndrome design using a novel eye tracking paradigm to measure habituation in preschoolers with NF1, children with idiopathic ASD and typically developing (TD) children. Eye movements were recorded to examine fixation duration to simultaneously presented repeating and novel stimuli. Children with NF1 showed a bias for longer look durations to repeating stimuli at the expense of novel stimuli, and slower habituation in NF1 was associated with elevated ASD traits. These findings could indicate aberrant modulation of bottom-up attentional networks that interact with the emergence of ASD phenotypes. [ABSTRACT FROM AUTHOR]

Children with neurofibromatosis type 1 (NF1) are at considerable risk for cognitive difficulties, including visuospatial deficits and executive dysfunction. This study aimed to (1) assess the overall performance of children with NF1 on the Rey-Osterrieth Complex Figure Test (RCFT) compared to unaffected siblings and (2) examine neuropsychological predictors of RCFT performance in children with NF1. A retrospective clinical audit was performed on neuropsychological records from a multidisciplinary NF1 Clinic in Australia. We searched for children that had completed an assessment between 2000 and 2015 which included the RCFT and other neuropsychological outcomes in this study. These included the Wechsler Intelligence Scale for Children, Judgment of Line Orientation (JLO), Tower of London test, Conners ADHD Scales, and the Behavioral Rating Inventory of Executive Function (BRIEF). The study population consisted of 191 children with NF1 aged 6–16 years, and 55 unaffected siblings recruited from a separate study. Results revealed that 62% of children with NF1 performed at or below the first percentile on the RCFT copy, which was significantly worse than their unaffected siblings. Visuospatial skills, parent-rated executive abilities, ADHD symptoms, and intellectual skills all predicted poorer performance on the RCFT copy, however the best fitting multiple regression model only contained the JLO, BRIEF Metacognition Index, and chronological age. The JLO emerged as the strongest predictor of RCFT performance. This study provides evidence that visuospatial deficits are a key driver of reduced RCFT performance in NF1 and that executive skills as well as a younger age are also independent predictors of RCFT performance. [ABSTRACT FROM AUTHOR]

The article discusses the study by Wein, N. and colleagues to demonstrate that initiation of Duchenne muscular dystrophy (DMD) exon 6 translation is driven by an internal ribosome entry site (IRES) in exon 5 nucleic acid sequence and this allows translation of truncated form of dystrophin protein. It states that mass spectrometry on muscle biopsy tissue of an asymptomatic individual was carried out and a form of dystrophin was detected and therapeutic use of IRES modulation was established.

Simple Summary: Difficulties in sensory processing are often found in neurodevelopmental disorders and can significantly impact how a child responds to and functions within their environment. Studies examining sensory processing in children with neurofibromatosis type 1 (NF1) are sparse. This cross-sectional study aims to address this gap by examining parent-reported sensory processing in a sample of 152 children with NF1. Approximately 61% of children with NF1 displayed differences in how they respond to sensory stimuli when compared to a typically developing control group. These difficulties were seen equally across ages and sex and were found to be associated with a higher degree of autistic behaviors, ADHD symptoms, lower adaptive skills, poorer social skills, and increased anxiety and affective symptoms. The results highlight the importance of accommodating multisensory processing difficulties at home and school when deciding how to support a child with NF1 across environments. Despite the evidence of elevated autistic behaviors and co-occurring neurodevelopmental difficulties in many children with neurofibromatosis type 1 (NF1), we have a limited understanding of the sensory processing challenges that may occur with the condition. This study examined the sensory profile of children and adolescents with NF1 and investigated the relationships between the sensory profiles and patient characteristics and neuropsychological functioning. The parent/caregivers of 152 children with NF1 and 96 typically developing children completed the Sensory Profile 2 (SP2), along with standardized questionnaires assessing autistic behaviors, ADHD symptoms, internalizing symptoms, adaptive functioning, and social skills. Intellectual functioning was also assessed. The SP2 data indicated elevated sensory processing problems in children with NF1 compared to typically developing children. Over 40% of children with NF1 displayed differences in sensory registration (missing sensory input) and were unusually sensitive to and unusually avoidant of sensory stimuli. Sixty percent of children with NF1 displayed difficulties in one or more sensory modalities. Elevated autistic behaviors and ADHD symptoms were associated with more severe sensory processing difficulties. This first detailed assessment of sensory processing, alongside other clinical features, in a relatively large cohort of children and adolescents with NF1 demonstrates the relationships between sensory processing differences and adaptive skills and behavior, as well as psychological well-being. Our characterization of the sensory profile within a genetic syndrome may help facilitate more targeted interventions to support overall functioning. [ABSTRACT FROM AUTHOR]

This study investigated sex and age differences in autistic behaviours in children with neurofibromatosis type 1 (NF1) who scored within the clinical range on the Social Responsiveness Scale - Second Edition (T score ≥ 60). Thirty-four males and 28 females (3–16 years) were assessed with the Autism Diagnostic Observation Schedule - Second Edition and Autism Diagnostic Interview - Revised. Across both measures, males exhibited greater social communication deficits relative to females. Age-related abatement of social communication difficulties was observed for males but not females. Conversely, no sex differences were found for restricted/repetitive behaviours, which were stable over time for both males and females. The findings are discussed within the context of broader neurodevelopmental considerations that are common in NF1. [ABSTRACT FROM AUTHOR]

Reports on the absence of actin-binding proteins in muscle biopsies of patients with muscular dystrophy. Identification of actinin deficiency by immunocytochemistry; Determination of the frequency and ethnic distribution in the general population; Reevaluation of previous studies on the loss actinin in patients with Duchenne muscular dystrophy.

Background: A high proportion of patients with neurofibromatosis type 1 (NF1) present with functional hearing deficiency as a result of neural abnormality in the late auditory brainstem. Methods: In this randomized, two-period crossover study, we investigated the hypothesis that remote-microphone listening devices can ameliorate hearing and communication deficits in affected school-aged children (7–17 years). Speech perception ability in background noise was evaluated in device-active and inactive conditions using the CNC-word test. Participants were then randomized to one of two treatment sequences: (1) inactive device for two weeks (placebo), followed by active device use for two weeks, or (2) active device for 2 weeks, followed by inactive device for 2 weeks. Listening and communication ratings (LIFE-R Questionnaire) were obtained at baseline and at the end of each treatment phase. Results: Each participant demonstrated functional hearing benefits with remote-microphone use. All showed a speech perception in noise increase when the device was activated with a mean phoneme-score difference of 16.4% (p < 0.001) and reported improved listening/communication abilities in the school classroom (mean difference: 23.4%; p = 0.017). Discussion: Conventional hearing aids are typically ineffective as a treatment for auditory neural dysfunction, making sounds louder, but not clearer for affected individuals. In this study, we demonstrate that remote-microphone technologies are acceptable/tolerable in pediatric patients with NF1 and can ameliorate their hearing deficits. Conclusion: Remote-microphone listening systems offer a viable treatment option for children with auditory deficits associated with NF1. [ABSTRACT FROM AUTHOR]

An estimated 1.5 billion people worldwide are deficient in the skeletal muscle protein α-actinin-3 due to homozygosity for the common ACTN3 R577X polymorphism. α-Actinin-3 deficiency influences muscle performance in elite athletes and the general population. The sarcomeric α-actinins were originally characterised as scaffold proteins at the muscle Z-line. Through studying the Actn3 knockout mouse and α-actinin-3 deficient humans, significant progress has been made in understanding how ACTN3 genotype alters muscle function, leading to an appreciation of the diverse roles that α-actinins play in muscle. The α-actinins interact with a number of partner proteins, which broadly fall into three biological pathways—structural, metabolic and signalling. Differences in functioning of these pathways have been identified in α-actinin-3 deficient muscle that together contributes to altered muscle performance in mice and humans. Here we discuss new insights that have been made in understanding the molecular mechanisms that underlie the consequences of α-actinin-3 deficiency. [ABSTRACT FROM AUTHOR]

Background: A common polymorphism (R577X) in the ACTN3 gene results in the complete absence of the Z-disc protein α-actinin-3 from fast-twitch muscle fibres in ~ 16% of the world's population. This single gene polymorphism has been subject to strong positive selection pressure during recent human evolution. Previously, using an Actn3KO mouse model, we have shown in fast-twitch muscles, eccentric contractions at L0 + 20% stretch did not cause eccentric damage. In contrast, L0 + 30% stretch produced a significant ~ 40% deficit in maximum force; here, we use isolated single fast-twitch skeletal muscle fibres from the Actn3KO mouse to investigate the mechanism underlying this. Methods: Single fast-twitch fibres are separated from the intact muscle by a collagenase digest procedure. We use label-free second harmonic generation (SHG) imaging, ultra-fast video microscopy and skinned fibre measurements from our MyoRobot automated biomechatronics system to study the morphology, visco-elasticity, force production and mechanical strength of single fibres from the Actn3KO mouse. Data are presented as means ± SD and tested for significance using ANOVA. Results: We show that the absence of α-actinin-3 does not affect the visco-elastic properties or myofibrillar force production. Eccentric contractions demonstrated that chemically skinned Actn3KO fibres are mechanically weaker being prone to breakage when eccentrically stretched. Furthermore, SHG images reveal disruptions in the myofibrillar alignment of Actn3KO fast-twitch fibres with an increase in Y-shaped myofibrillar branching. Conclusions: The absence of α-actinin-3 from the Z-disc in fast-twitch fibres disrupts the organisation of the myofibrillar proteins, leading to structural weakness. This provides a mechanistic explanation for our earlier findings that in vitro intact Actn3KO fast-twitch muscles are significantly damaged by L0 + 30%, but not L0 + 20%, eccentric contraction strains. Our study also provides a possible mechanistic explanation as to why α-actinin-3-deficient humans have been reported to have a faster decline in muscle function with increasing age, that is, as sarcopenia reduces muscle mass and force output, the eccentric stress on the remaining functional α-actinin-3 deficient fibres will be increased, resulting in fibre breakages. [ABSTRACT FROM AUTHOR]

Children with neurofibromatosis type 1 (NF1) often experience executive dysfunction, attention deficit/hyperactivity disorder (ADHD) symptoms and poor social skills, however, the nature of the relationships between these domains in children with NF1 is unclear. This study investigated these relationships using primary caregiver ratings of executive functions, ADHD symptoms and social skills in children with NF1. Participants were 136 children with NF1 and 93 typically developing (TD) controls aged 3–15 years recruited from 3 multidisciplinary neurofibromatosis clinics in Melbourne and Sydney, Australia, and Washington DC, USA. Mediation analysis was performed on primary outcome variables: parent ratings of executive functions (Behavior Rating Inventory of Executive Function, Metacognition Index), ADHD symptoms (Conners-3/Conners ADHD Diagnostic and Statistical Manual for Mental Disorders Scales) and social skills (Social Skills Improvement System-Rating Scale), adjusting for potential confounders (full scale IQ, sex, and social risk). Results revealed significantly poorer executive functions, elevated ADHD symptoms and reduced social skills in children with NF1 compared to controls. Poorer executive functions significantly predicted elevated ADHD symptoms and poorer social skills. Elevated ADHD symptoms significantly mediated the relationship between executive functions and social skills problems although did not fully account for social dysfunction. This study provides evidence for the importance of targeting ADHD symptoms as part of future interventions aimed at promoting prosocial behaviors in children with NF1. [ABSTRACT FROM AUTHOR]

Background: Existing research has demonstrated elevated autistic behaviours in children with neurofibromatosis type 1 (NF1), but the autistic phenotype and its relationship to other neurodevelopmental manifestations of NF1 remains unclear. To address this gap, we performed detailed characterisation of autistic behaviours in children with NF1 and investigated their association with other common NF1 child characteristics. Methods: Participants were drawn from a larger cross-sectional study examining autism in children with NF1. The population analysed in this study scored above threshold on the Social Responsiveness Scale-Second Edition (T-score ≥ 60; 51% larger cohort) and completed the Autism Diagnostic Interview-Revised (ADI-R) and/or the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). All participants underwent evaluation of their intellectual function, and behavioural data were collected via parent questionnaires. Results: The study cohort comprised 68 children (3–15 years). Sixty-three per cent met the ADOS-2 'autism spectrum' cut-off, and 34% exceeded the more stringent threshold for 'autistic disorder' on the ADI-R. Social communication symptoms were common and wide-ranging, while restricted and repetitive behaviours (RRBs) were most commonly characterised by 'insistence on sameness' (IS) behaviours such as circumscribed interests and difficulties with minor changes. Autistic behaviours were weakly correlated with hyperactive/impulsive attention deficit hyperactivity disorder (ADHD) symptoms but not with inattentive ADHD or other behavioural characteristics. Language and verbal IQ were weakly related to social communication behaviours but not to RRBs. Limitations: Lack of genetic validation of NF1, no clinical diagnosis of autism, and a retrospective assessment of autistic behaviours in early childhood. Conclusions: Findings provide strong support for elevated autistic behaviours in children with NF1. While these behaviours were relatively independent of other NF1 comorbidities, the importance of taking broader child characteristics into consideration when interpreting data from autism-specific measures in this population is highlighted. Social communication deficits appear similar to those observed in idiopathic autism and are coupled with a unique RRB profile comprising prominent IS behaviours. This autistic phenotype and its relationship to common NF1 comorbidities such as anxiety and executive dysfunction will be important to examine in future research. Current findings have important implications for the early identification of autism in NF1 and clinical management. [ABSTRACT FROM AUTHOR]

Duchenne muscular dystrophy (DMD) is the second most common fatal genetic disease in humans and is characterized by the absence of a functional copy of the protein dystrophin from skeletal muscle. In dystrophin-negative humans and rodents, regenerated skeletal muscle fibers show abnormal branching. The number of fibers with branches and the complexity of branching increases with each cycle of degeneration/regeneration. Previously, using the mdx mouse model of DMD, we have proposed that once the number and complexity of branched fibers present in dystrophic fast-twitch EDL muscle surpasses a stable level, we term the "tipping point," the branches, in and of themselves, mechanically weaken the muscle by rupturing when subjected to high forces during eccentric contractions. Here, we use the slow-twitch soleus muscle from the dystrophic mdx mouse to study prediseased "periambulatory" dystrophy at 2-3 wk, the peak regenerative "adult" phase at 6-9 wk, and "old" at 58-112 wk. Using isolated mdx soleus muscles, we examined contractile function and response to eccentric contraction correlated with the amount and complexity of regenerated branched fibers. The intact muscle was enzymatically dispersed into individual fibers in order to count fiber branching and some muscles were optically cleared to allow laser scanning confocal microscopy. We demonstrate throughout the lifespan of the mdx mouse that dystrophic slow-twitch soleus muscle is no more susceptible to eccentric contraction-induced injury than age-matched littermate controls and that this is correlated with a reduction in the number and complexity of branched fibers compared with fast-twitch dystrophic EDL muscles. [ABSTRACT FROM AUTHOR]

Abstract: Accurate and fast measurement of muscle fibre size and evaluation of fibre type proportions in large cross-sectional areas remains challenging as existing methods require extensive manual measurements. In this study, we assessed the fibre morphometry of ∼1000 fibres in mouse and human control and diseased muscle cross-sections. We compared fibre size, percentage fibre proportion and percentage fibre surface area results obtained by an automated method using MetaMorph® with those obtained manually using Image Pro. Data collection using MetaMorph® software was faster and produced similar results to those obtained using Image Pro. The ability to quickly and accurately measure large numbers of fibres with MetaMorph® allows the researcher to make a more precise assessment of fibre type and fibre size changes in human muscle biopsies and animal models of muscle disease. [ABSTRACT FROM AUTHOR]

Charcot-Marie-Tooth disease affects foot and ankle strength from the earliest stages of the disease; however, little is known about factors influencing normal strength development or the pathogenesis of foot weakness and deformity in Charcot-Marie-Tooth disease. The authors investigated factors associated with foot and ankle strength in healthy preschool-age children and compared to age-matched cases of Charcot-Marie-Tooth disease type 1A. In healthy children, ankle dorsiflexion range of motion was one of the strongest independent correlates of foot and ankle strength. Compared with healthy children, those with Charcot-Marie-Tooth disease type 1A had significantly less dorsiflexion strength and range as well as imbalance in inversion-to-eversion and plantarflexion-to-dorsiflexion strength ratios. Given the association between ankle dorsiflexion strength and range in the healthy children, and the abnormality of these parameters in Charcot-Marie-Tooth disease, investigation of the cause-effect relationship is warranted to identify more targeted therapy and further understand the pathogenesis of foot deformity in Charcot-Marie-Tooth disease. [ABSTRACT FROM AUTHOR]

Background: 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. Results: 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. Conclusions: 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. [ABSTRACT FROM AUTHOR]

Abstract: Foot weakness occurs in many paediatric neuromuscular disorders, which overtime can cause considerable functional motor difficulties. Measuring foot strength with hand-held dynamometry is reliable in preschool-age children, but its validity in this age group is unknown. If foot strength measures are collected as endpoints in clinical trials, they should represent functionally meaningful outcomes. We evaluated the foot strength-motor function relationship in 60 healthy children aged 2–4 years. Foot strength measures included inversion, eversion, dorsiflexion and plantarflexion using hand-held dynamometry. Motor function parameters included time to run 10-m, standing long jump distance and vertical jump height. Measures of foot strength showed significant correlations with all measures of motor function (r =0.40–0.57, p <0.001). Hand-held dynamometry may be used as a valid and functionally meaningful measure of foot strength in very young children. [Copyright &y& Elsevier]

Background: Carnitine palmitoyltransferase-II deficiency (CPT-II deficiency) is a rare disorder of lipid metabolism, in which the accumulation of long-chain acylcarnitines is a diagnostic marker. HPLC with fluorescence detection is an attractive analysis method due to its favorable combination of sensitivity, specificity, ease of analysis and minimal capital equipment costs. Methods: Long-chain acylcarnitines were isolated from tissue homogenates (0.5–2 mg wet weight) or plasma (50 μl) using silica gel columns and derivatized with 2-(2,3-naphthalimino)ethyl trifluoromethanesulfonate. Quantitation was by HPLC and fluorescence detection with standard curves (0.0–5.0 nmol/ml) for myristoyl-, palmitoleoyl-, palmitoyl-, oleoyl- and stearoylcarnitine using heptadecanoylcarnitine as the internal standard. Results: Significantly greater amounts of long-chain acylcarnitines were quantified in patients with CPT-II deficiency when compared to controls; e.g. (nmol/ml in patient plasma, controls mean±standard deviation): myristoylcarnitine (0.3, not detectable), palmitoleoylcarnitine (0.5, 0.1±0.1), palmitoylcarnitine (0.9, 0.1±0.0), oleoylcarnitine (3.0, 0.2±0.1), stearoylcarnitine (0.4, not detectable). Conclusions: This method can be used to quantitate long-chain acylcarnitines, illustrating their accumulation in CPT-II deficiency. The analysis was accomplished using inexpensive and widely available instrumentation and is appropriate for research investigators who require precise quantitation of long-chain acylcarnitines in complex biological samples. [Copyright &y& Elsevier]

Focal and segmental glomerulosclerosis (FSGS) is a common, non-specific renal lesion. Although it is often secondary to other disorders, including HIV infection, obesity, hypertension and diabetes, FSGS also appears as an isolated, idiopathic condition. FSGS is characterized by increased urinary protein excretion and decreasing kidney function. Often, renal insufficiency in affected patients progresses to end-stage renal failure, a highly morbid state requiring either dialysis therapy or kidney transplantation. Here we present evidence implicating mutations in the gene encoding α-actinin-4 (ACTN4; ref. 2), an actin-filament crosslinking protein, as the cause of disease in three families with an autosomal dominant form of FSGS. In vitro, mutant α-actinin-4 binds filamentous actin (F-actin) more strongly than does wild-type α-actinin-4. Regulation of the actin cytoskeleton of glomerular podocytes may be altered in this group of patients. Our results have implications for understanding the role of the cytoskeleton in the pathophysiology of kidney disease and may lead to a better understanding of the genetic basis of susceptibility to kidney damage. [ABSTRACT FROM AUTHOR]

Homozygosity for the common ACTN3 null polymorphism (ACTN3 577X) results in α-actinin-3 deficiency in ~20% of humans worldwide and is linked to reduced sprint and power performance in both elite athletes and the general population. α-Actinin-3 deficiency is also associated with reduced muscle mass, increased risk of sarcopenia, and altered muscle wasting response induced by denervation and immobilization. Here, we show that α-actinin-3 plays a key role in the regulation of protein synthesis and breakdown signaling in skeletal muscle and influences muscle mass from early postnatal development. We also show that α-actinin-3 deficiency reduces the atrophic and anti-inflammatory response to the glucocorticoid dexamethasone in muscle and protects against dexamethasone-induced muscle wasting in female but not male mice. The effects of α-actinin-3 deficiency on muscle mass regulation and response to muscle wasting provide an additional mechanistic explanation for the positive selection of the ACTN3 577X allele in recent human history. [ABSTRACT FROM AUTHOR]

Objective: Reading difficulties are one of the most significant challenges for children with neurofibromatosis type 1 (NF1). The aims of this study were to identify and categorize the types of reading impairments experienced by children with NF1 and to establish predictors of poor reading in this population. Method: Children aged 7–12 years with NF1 (n = 60) were compared with typically developing children (n = 36). Poor word readers with NF1 were classified according to impairment type (i.e., phonological, surface, mixed), and their reading subskills were compared. A hierarchical multiple regression was conducted to identify predictors of word reading. Results: Compared to controls, children with NF1 demonstrated significantly poorer literacy abilities. Of the 49 children with NF1 classified as poor readers, 20 (41%) were classified with phonological dyslexia, 24 (49%) with mixed dyslexia, and 5 (10%) fell outside classification categories. Children with mixed dyslexia displayed the most severe reading impairments. Stronger working memory, better receptive language, and fewer inattentive behaviors predicted better word reading skills. Conclusions: The majority of children with NF1 experience deficits in key reading skills which are essential for them to become successful readers. Weaknesses in working memory, receptive language, and attention are associated with reading difficulties in children with NF1. [ABSTRACT FROM AUTHOR]

The protein α-actinin-3 expressed in fast-twitch skeletal muscle fiber is absent in 1.5 billion people worldwide due to homozygosity for a nonsense polymorphism in ACTN3 (R577X). The prevalence of the 577X allele increased as modern humans moved to colder climates, suggesting a link between α-actinin-3 deficiency and improved cold tolerance. Here, we show that humans lacking α-actinin-3 (XX) are superior in maintaining core body temperature during cold-water immersion due to changes in skeletal muscle thermogenesis. Muscles of XX individuals displayed a shift toward more slow-twitch isoforms of myosin heavy chain (MyHC) and sarcoplasmic reticulum (SR) proteins, accompanied by altered neuronal muscle activation resulting in increased tone rather than overt shivering. Experiments on Actn3 knockout mice showed no alterations in brown adipose tissue (BAT) properties that could explain the improved cold tolerance in XX individuals. Thus, this study provides a mechanism for the positive selection of the ACTN3 X-allele in cold climates and supports a key thermogenic role of skeletal muscle during cold exposure in humans. [ABSTRACT FROM AUTHOR]

Aim: We examined key features of two outcome measures for social dysfunction and autism spectrum disorder traits, the Social Responsiveness Scale, Second Edition (SRS-2) and the Social Skills Improvement System - Rating Scales (SSIS-RS), in children with neurofibromatosis type 1 (NF1). The aim of the study was to provide objective evidence as to which behavioural endpoint should be used in clinical trials.Method: Cross-sectional behavioural and demographic data were pooled from four paediatric NF1 tertiary referral centres in Australia and the United States (N=122; 65 males, 57 females; mean age [SD] 9y 2mo [3y], range 3-15y).Results: Distributions of SRS-2 and SSIS-RS scores were unimodal and both yielded deficits, with a higher proportion of severely impaired scores on the SRS-2 (16.4%) compared to the SSIS-RS (8.2%). Pearson's product-moment correlations revealed that both questionnaires were highly related to each other (r=-0.72, p<0.001) and to measures of adaptive social functioning (both p<0.001). Both questionnaires were significantly related to attention-deficit/hyperactivity disorder symptoms, but only very weakly associated with intelligence.Interpretation: The SRS-2 and SSIS-RS capture social dysfunction associated with NF1, suggesting both may be suitable choices for assessing social outcomes in this population in a clinical trial. However, careful thought needs to be given to the nature of the intervention when selecting either as a primary endpoint.What This Paper Adds: The Social Responsiveness Scale, Second Edition yielded a large deficit relative to population norms. The Social Skills Improvement System - Rating Scales yielded a moderate deficit relative to population norms. Both scales were highly correlated, suggesting that they are measuring a unitary construct. [ABSTRACT FROM AUTHOR]

Aim: To examine visual attention to faces within social scenes in children with neurofibromatosis type 1 (NF1) and typically developing peers.Method: Using eye-tracking technology we investigated the time taken to fixate on a face and the percentage of time spent attending to faces relative to the rest of the screen within social scenes in 24 children with NF1 (17 females, seven males; mean age 10y 4mo [SD 1y 9mo]). Results were compared with those of 24 age-matched typically developing controls (11 females, 13 males; mean age 10y 3mo [SD 2y]).Results: There was no significant between-group differences in time taken to initially fixate on a face (p=0.617); however, children with NF1 spent less time attending to faces within scenes than controls (p=0.048). Decreased attention to faces was associated with elevated autism traits in children with NF1.Interpretation: Children with NF1 spend less time attending to faces than typically developing children when presented in social scenes. Our findings contribute to a growing body of literature suggesting that abnormal face processing is a key aspect of the social-cognitive phenotype of NF1 and appears to be related to autism spectrum disorder traits. Clinicians should consider the impact of reduced attention to faces when designing and implementing treatment programmes for social dysfunction in this population.What This Paper Adds: Children with neurofibromatosis type 1 (NF1) demonstrated atypical gaze behaviour when attending to faces. NF1 gaze behaviour was characterized by normal initial fixation on faces but shorter face dwell time. Decreased attention to faces was associated with elevated autism traits in the sample with NF1. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim: This cross-sectional study aimed to examine the preliteracy abilities of young children with neurofibromatosis type 1 (NF1) and to identify which of these abilities best predicted conventional literacy (spelling).Method: Forty-two children with NF1 (23 males, 19 females; mean age [SD] 5y 6mo [6mo]) were compared with 32 unaffected children (15 males, 17 females; mean age [SD] 5y 4mo [6mo]). All children completed a comprehensive cognitive assessment including measures of phonological processing (phonological awareness, phonological memory, rapid automatic naming) and letter-sound knowledge.Results: Children with NF1 performed significantly poorer than the comparison group across all cognitive and preliteracy domains, with specific weaknesses evident in phonological awareness (F1,68 =14.13, p<0.001, partial η2 =0.17), phonological memory (F1,68 =13.87, p<0.001, partial η2 =0.17), and letter-sound knowledge (F1,71 =5.65, p=0.020, partial η2 =0.07). Within the group with NF1 group, over a third of children demonstrated impairment in at least one phonological processing domain and the risk of phonological impairment was 5.60 times that of unaffected children. Children's letter-sound knowledge was the strongest predictor of conventional literacy (spelling).Interpretation: This study establishes that preliteracy deficits are present and detectable in young children with NF1. As a result of the high incidence of preliteracy impairment, we recommend screening phonological awareness and letter-sound knowledge to identify risk of future learning disorders.What This Paper Adds: Young children with neurofibromatosis type 1 are at elevated risk of preliteracy deficits. The most affected domains are phonological awareness and phonological memory. Letter-sound knowledge is the strongest predictor of conventional literacy (spelling). [ABSTRACT FROM AUTHOR]

A striking pathological feature of dystrophinopathies is the presence of morphologically abnormal branched skeletal muscle fibers. The deterioration of muscle contractile function in Duchenne muscular dystrophy is accompanied by both an increase in number and complexity of these branched fibers. We propose that when number and complexity of branched fibers reaches a critical threshold, or "tipping point," the branches in and of themselves are the site of contraction-induced rupture. In the present study, we use the dystrophic mdx mouse and littermate controls to study the prediseased dystrophic fast-twitch extensor digitorum longus (EDL) muscle at 2-3 wk, the peak myonecrotic phase at 6-9 wk, and finally, "old," at 58-112 wk. Using a combination of isolated muscle function contractile measurements coupled with single-fiber imaging and confocal microscope imaging of cleared whole muscles, we identified a distinct pathophysiology, acute fiber rupture at branch nodes, which occurs in "old" fast-twitch EDL muscle approaching the end stage of the dystrophinopathy muscle disease, where the EDL muscles are entirely composed of complexed branched fibers. This evidence supports our concept of "tipping point" where the number and extent of fiber branching reach a level where the branching itself terminally compromises muscle function, irrespective of the absence of dystrophin. [ABSTRACT FROM AUTHOR]

Loss of expression of ACTN3 , due to homozygosity of the common null polymorphism (p.Arg577X), is underrepresented in elite sprint/power athletes and has been associated with reduced muscle mass and strength in humans and mice. To investigate ACTN3 gene dosage in performance and whether expression could enhance muscle force, we performed meta-analysis and expression studies. Our general meta-analysis using a Bayesian random effects model in elite sprint/power athlete cohorts demonstrated a consistent homozygous-group effect across studies (per allele OR = 1.4, 95% CI 1.3–1.6) but substantial heterogeneity in heterozygotes. In mouse muscle, rAAV-mediated gene transfer overexpressed and rescued α-actinin-3 expression. Contrary to expectation, in vivo “doping” of ACTN3 at low to moderate doses demonstrated an absence of any change in function. At high doses, ACTN3 is toxic and detrimental to force generation, to demonstrate gene doping with supposedly performance-enhancing isoforms of sarcomeric proteins can be detrimental for muscle function. Restoration of α-actinin-3 did not enhance muscle mass but highlighted the primary role of α-actinin-3 in modulating muscle metabolism with altered fatiguability. This is the first study to express a Z-disk protein in healthy skeletal muscle and measure the in vivo effect. The sensitive balance of the sarcomeric proteins and muscle function has relevant implications in areas of gene doping in performance and therapy for neuromuscular disease. [ABSTRACT FROM AUTHOR]

Aim: To investigate whether in-the-moment diary reports of daily experience, taken collectively, are a valid representation of health-related quality of life (HRQL).Methods: A total of 35 boys with Duchenne muscular dystrophy (DMD) were recruited through four neuromuscular care providers across Australia. Participants completed the PedsQL™ Generic Core scales and one week of experience-sampling diary reporting on a personal digital assistant. Rasch analysis was undertaken on the diary data to derive a single valid measure score. The resulting measure score for each participant was correlated with the summary score from the PedsQL™ Generic Core scales to examine whether daily experience was representative of HRQL.Results: The daily diary method showed good metric properties, with adequate goodness of fit for data from items and participants suggesting unidimensionality of the construct: quality of everyday experience. The correlation of the daily diary measure score with overall PedsQL™ summary score showed moderate agreement (r = .60, p = 0.001).Conclusions: The benefits of measuring daily quality of life include detailed descriptions of day-to-day experiences of children without the need for retrospective recall. Diary methods on an electronic platform or software application for personal devices may be a useful tool to understand HRQL as the repeated measures data provide a detailed experience directly from the child and the platform makes data completion highly motivating. [ABSTRACT FROM AUTHOR]

Objectives: To examine hierarchical visuospatial processing in children with neurofibromatosis type 1 (NF1), a single gene disorder associated with visuospatial impairments, attention deficits, and executive dysfunction. Methods: We used a modified Navon paradigm consisting of a large “global” shape composed of smaller “local” shapes that were either congruent (same) or incongruent (different) to the global shape. Participants were instructed to name either the global or local shape within a block. Reaction times, interference ratios, and error rates of children with NF1 (n=30) and typically developing controls (n=24) were compared. Results: Typically developing participants demonstrated the expected global processing bias evidenced by a vulnerability to global interference when naming local stimuli without a cost of congruence when naming global stimuli. NF1 participants, however, experienced significant interference from the unattended level when naming both local and global levels of the stimuli. Conclusions: Findings suggest that children with NF1 do not demonstrate the typical human bias of processing visual information from a global perspective. (JINS, 2017, 23, 446–450) [ABSTRACT FROM PUBLISHER]

TorsinA-interacting protein 1 ( TOR1AIP1 ) gene is a novel gene that has recently been described to cause limb-girdle muscular dystrophy (LGMD) with mild dilated cardiomyopathy. We report a family with mutations in TOR1AIP1 where the striking clinical feature is severe cardiac failure requiring cardiac transplant in two siblings, in addition to musculoskeletal weakness and muscular dystrophy. We demonstrate an absence of TOR1AIP1 protein expression in cardiac and skeletal muscles of affected siblings. We expand the phenotype of this gene to demonstrate the cardiac involvement and the importance of cardiac surveillance in patients with mutations in TOR1AIP1 . [ABSTRACT FROM AUTHOR]

Aims Mitsugumin-53 (MG53/TRIM72) is an E3-ubiquitin ligase that rapidly accumulates at sites of membrane injury and plays an important role in membrane repair of skeletal and cardiac muscle. MG53 has been implicated in cardiac ischaemia-reperfusion injury, and serum MG53 provides a biomarker of skeletal muscle injury in the mdx mouse model of Duchenne muscular dystrophy. We evaluated the clinical utility of MG53 as a biomarker of myocardial injury. Methods and results We performed Langendorff ischaemia-reperfusion injury on wild-type and dysferlin-null murine hearts, using dysferlin deficiency to effectively model more severe outcomes from cardiac ischaemia-reperfusion injury. MG53 released into the coronary effluent correlated strongly and significantly (r ¼ 0.79-0.85, P < 0.0001) with functional impairment after ischaemic injury. We initiated a clinical trial in paediatric patients undergoing corrective heart surgery, the first study of MG53 release with myocardial injury in humans. Unexpectedly, we reveal although MG53 is robustly expressed in rat and mouse hearts, MG53 is scant to absent in human, ovine, or porcine hearts. Absence of MG53 in 11 human heart specimens was confirmed using three separate antibodies to MG53, each subject to epitope mapping and confirmed immunospecificity using MG53-deficient muscle cells. Conclusion MG53 is an effective biomarker of myocardial injury and dysfunction in murine hearts. However, MG53 is not expressed in human heart and therefore does not hold utility as a clinical biomarker of myocardial injury. Although cardioprotective roles for endogenous myocardial MG53 cannot be extrapolated from rodents to humans, potential therapeutic application of recombinant MG53 for myocardial membrane injury prevails. [ABSTRACT FROM AUTHOR]

Despite numerous attempts to discover genetic variants associated with elite athletic performance, injury predisposition, and elite/world-class athletic status, there has been limited progress to date. Past reliance on candidate gene studies predominantly focusing on genotyping a limited number of single nucleotide polymorphisms or the insertion/deletion variants in small, often heterogeneous cohorts (i.e., made up of athletes of quite different sport specialties) have not generated the kind of results that could offer solid opportunities to bridge the gap between basic research in exercise sciences and deliverables in biomedicine. A retrospective view of genetic association studies with complex disease traits indicates that transition to hypothesis-free genome-wide approaches will be more fruitful. In studies of complex disease, it is well recognized that the magnitude of genetic association is often smaller than initially anticipated, and, as such, large sample sizes are required to identify the gene effects robustly. A symposium was held in Athens and on the Greek island of Santorini from 14 -17 May 2015 to review the main findings in exercise genetics and genomics and to explore promising trends and possibilities. The symposium also offered a forum for the development of a position stand (the Santorini Declaration). Among the participants, many were involved in ongoing collaborative studies (e.g., ELITE, GAMES, Gene SMART, GENESIS, and POWERGENE). A consensus emerged among participants that it would be advantageous to bring together all current studies and those recently launched into one new large collaborative initiative, which was subsequently named the Athlome Project Consortium. [ABSTRACT FROM AUTHOR]

Variants in ACTA1, which encodes α-skeletal actin, cause several congenital myopathies, most commonly nemaline myopathy. Autosomal recessive variants comprise approximately 10% of ACTA1 myopathy. All recessive variants reported to date have resulted in loss of skeletal α-actin expression from muscle and severe weakness from birth. Targeted next-generation sequencing in two brothers with congenital muscular dystrophy with rigid spine revealed homozygous missense variants in ACTA1. Skeletal α-actin expression was preserved in these patients. This report expands the clinical and histological phenotype of ACTA1 disease to include congenital muscular dystrophy with rigid spine and dystrophic features on muscle biopsy. This represents a new class of recessive ACTA1 variants, which do not abolish protein expression. [ABSTRACT FROM AUTHOR]

Dystroglycanopathies are a heterogeneous group of diseases with a broad phenotypic spectrum ranging from severe disorders with congenital muscle weakness, eye and brain structural abnormalities and intellectual delay to adult-onset limb-girdle muscular dystrophies without mental retardation. Most frequently the disease onset is congenital or during childhood. The exception is FKRP mutations, in which adult onset is a common presentation. Here we report eight patients from five non-consanguineous families where next generation sequencing identified mutations in the GMPPB gene. Six patients presented as an adult or adolescent- onset limb-girdle muscular dystrophy, one presented with isolated episodes of rhabdomyolysis, and one as a congenital muscular dystrophy. This report expands the phenotypic spectrum of GMPPB mutations to include limb-girdle muscular dystrophies with adult onset with or without intellectual disability, or isolated rhabdomyolysis. [ABSTRACT FROM AUTHOR]

Over 1.5 billion people lack the skeletal muscle fast-twitch fibre protein α-actinin-3 due to homozygosity for a common null polymorphism (R577X) in the ACTN3 gene. α-Actinin-3 deficiency is detrimental to sprint performance in elite athletes and beneficial to endurance activities. In the human genome, it is very difficult to find single-gene loss-of-function variants that bear signatures of positive selection, yet intriguingly, the ACTN3 null variant has undergone strong positive selection during recent evolution, appearing to provide a survival advantage where food resources are scarce and climate is cold. We have previously demonstrated that α-actinin-3 deficiency in the Actn3 KO mouse results in a shift in fast-twitch fibres towards oxidative metabolism, which would be more “energy efficient” in famine, and beneficial to endurance performance. Prolonged exposure to cold can also induce changes in skeletal muscle similar to those observed with endurance training, and changes in Ca2+ handling by the sarcoplasmic reticulum (SR) are a key factor underlying these adaptations. On this basis, we explored the effects of α-actinin-3 deficiency on Ca2+ kinetics in single flexor digitorum brevis muscle fibres from Actn3 KO mice, using the Ca2+-sensitive dye fura-2. Compared to wild-type, fibres of Actn3 KO mice showed: (i) an increased rate of decay of the twitch transient; (ii) a fourfold increase in the rate of SR Ca2+ leak; (iii) a threefold increase in the rate of SR Ca2+ pumping; and (iv) enhanced maintenance of tetanic Ca2+ during fatigue. The SR Ca2+ pump, SERCA1, and the Ca2+-binding proteins, calsequestrin and sarcalumenin, showed markedly increased expression in muscles of KO mice. Together, these changes in Ca2+ handling in the absence of α-actinin-3 are consistent with cold acclimatisation and thermogenesis, and offer an additional explanation for the positive selection of the ACTN3 577X null allele in populations living in cold environments during recent evolution. [ABSTRACT FROM AUTHOR]

Aim Motor skill impairment and cognitive dysfunction are commonly reported features of neurofibromatosis type 1 ( NF1). We characterized and determined the relationship between motor impairment, gait variables, and cognitive function in children and adolescents with NF1. Method Motor function, gait, and neurocognitive abilities were assessed in 46 children and adolescents with NF1 (26 males, 20 females; age range 7-17y; mean age 11y 1mo, SD 3y 2mo). Tests to establish correlations between neurocognitive, motor, and gait variables were performed. Results Compared with normative data, 28/39 of our NF1 cohort demonstrated impaired performance for balance and upper limb coordination and 16/38 for running speed and agility. Gait data revealed a strategy to preserve balance at the expense of velocity, with the unexpected exception of a tendency for reduced base of support. Neurocognitive testing confirmed mean IQ in the low average range (86.0) and deficits in spatial working memory and strategy generation. Significant correlations between a number of neurocognitive measures and motor abilities and gait were identified. The largest associations were between gait width and spatial working memory ( r=0.594) and running speed and agility with strategy generation ( r=0.549). Interpretation We have identified a relationship between balance, running speed and agility, gait, and cognition in children with NF1. Findings suggest a shared abnormal neurodevelopmental process underlying some cognitive and motor abilities in NF1. Results are discussed within the context of evidence highlighting abnormal dopamine-mediated corticostriatal circuitry in NF1. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is a common genetic condition associated with cognitive and social dysfunction as well as abnormal brain structure. The pathophysiology underlying social dysfunction in NF1 is poorly understood. Here, we investigate for the first time whether there is a broad deficit of social cognition in NF1 and explore the neural correlates for these deficits. Twenty-nine adults with NF1 and 30 controls were administered an ecologically based test of social cognition, The Awareness of Social Inference Test (TASIT), to identify deficits in emotion recognition and sarcasm detection. We employed voxel-based morphometry in a subset of NF1 patients ( n = 16) and 16 additional controls to examine the neural correlates of these deficits. Results indicated that adults with NF1 were impaired in their ability to understand paradoxical sarcasm and their capacity to recognize emotion, particularly anger. TASIT performance was not associated with measures of attention, visuospatial skills or executive function. Relative to controls, gray matter (GM) volume within the right superior temporal gyrus (STG) was decreased, after controlling for total brain volume. Decreased volume in this region was significantly associated with social cognitive deficits in adults with NF1. We conclude that patients with NF1 are at high risk for a social cognitive deficit and provide evidence for a neuroanatomical basis for this deficit; GM volumetric reductions in the right STG. These findings improve our understanding of the nature of social interaction impairments in NF1 and add to the growing body of literature indicating the STG as a critical brain region for social cognition. Hum Brain Mapp 35:2372-2382, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Congenital muscular dystrophies (CMDs) are early onset disorders of muscle with histological features suggesting a dystrophic process. The congenital muscular dystrophies as a group encompass great clinical and genetic heterogeneity so that achieving an accurate genetic diagnosis has become increasingly challenging, even in the age of next generation sequencing. In this document we review the diagnostic features, differential diagnostic considerations and available diagnostic tools for the various CMD subtypes and provide a systematic guide to the use of these resources for achieving an accurate molecular diagnosis. An International Committee on the Standard of Care for Congenital Muscular Dystrophies composed of experts on various aspects relevant to the CMDs performed a review of the available literature as well as of the unpublished expertise represented by the members of the committee and their contacts. This process was refined by two rounds of online surveys and followed by a three-day meeting at which the conclusions were presented and further refined. The combined consensus summarized in this document allows the physician to recognize the presence of a CMD in a child with weakness based on history, clinical examination, muscle biopsy results, and imaging. It will be helpful in suspecting a specific CMD subtype in order to prioritize testing to arrive at a final genetic diagnosis. [Copyright &y& Elsevier]

The ability to obtain accurate and reproducible data using quantitative real-time Polymerase Chain Reaction (RT-qPCR) is limited by the process of data normalization. The use of ‘housekeeping’ or ‘reference’ genes is the most common technique used to normalize RT-qPCR data. However, commonly used reference genes are often poorly validated and may change as a result of genetic background, environment and experimental intervention. Here we present an analysis of 10 reference genes in mouse skeletal muscle (Actb, Aldoa, Gapdh, Hprt1, Ppia, Rer1, Rn18s, Rpl27, Rpl41 and Rpl7L1), which were identified as stable either by microarray or in the literature. Using the MIQE guidelines we compared wild-type (WT) mice across three genetic backgrounds (R129, C57BL/6j and C57BL/10) as well as analyzing the α-actinin-3 knockout (Actn3 KO) mouse, which is a model of the common null polymorphism (R577X) in human ACTN3. Comparing WT mice across three genetic backgrounds, we found that different genes were more tightly regulated in each strain. We have developed a ranked profile of the top performing reference genes in skeletal muscle across these common mouse strains. Interestingly the commonly used reference genes; Gapdh, Rn18s, Hprt1 and Actb were not the most stable. Analysis of our experimental variant (Actn3 KO) also resulted in an altered ranking of reference gene suitability. Furthermore we demonstrate that a poor reference gene results in increased variability in the normalized expression of a gene of interest, and can result in loss of significance. Our data demonstrate that reference genes need to be validated prior to use. For the most accurate normalization, it is important to test several genes and use the geometric mean of at least three of the most stably expressed genes. In the analysis of mouse skeletal muscle, strain and intervention played an important role in selecting the most stable reference genes. [ABSTRACT FROM AUTHOR]

Nemaline myopathy (NM) is a rare congenital muscle disorder primarily affecting skeletal muscles that results in neonatal death in severe cases as a result of associated respiratory insufficiency. NM is thought to be a disease of sarcomeric thin filaments as six of eight known genes whose mutation can cause NM encode components of that structure, however, recent discoveries of mutations in non-thin filament genes has called this model in question. We performed whole-exome sequencing and have identified recessive small deletions and missense changes in the Kelch-like family member 41 gene (KLHL41) in four individuals from unrelated NM families. Sanger sequencing of 116 unrelated individuals with NM identified compound heterozygous changes in KLHL41 in a fifth family. Mutations in KLHL41 showed a clear phenotype-genotype correlation: Frameshift mutations resulted in severe phenotypes with neonatal death, whereas missense changes resulted in impaired motor function with survival into late childhood and/or early adulthood. Functional studies in zebrafish showed that loss of Klhl41 results in highly diminished motor function and myofibrillar disorganization, with nemaline body formation, the pathological hallmark of NM. These studies expand the genetic heterogeneity of NM and implicate a critical role of BTB-Kelch family members in maintenance of sarcomeric integrity in NM. [ABSTRACT FROM AUTHOR]