Novel deletion of lysine 7 expands the clinical, histopathological and genetic spectrum of TPM2-related myopathies.

The ß-tropomyosin gene encodes a component of the sarcomeric thin filament. Rod-shaped dimers of tropomyosin regulate actin-myosin interactions and ß-tropomyosin mutations have been associated with nemaline myopathy, cap myopathy, Escobar syndrome and distal arthrogryposis types 1A and 2B. In this study, we expand the allelic spectrum of ß-tropomyosin-related myopathies through the identification of a novel ß-tropomyosin mutation in two clinical contexts not previously associated with ß-tropomyosin. The first clinical phenotype is core-rod myopathy, with a ß-tropomyosin mutation uncovered by whole exome sequencing in a family with autosomal dominant distal myopathy and muscle biopsy features of both minicores and nemaline rods. The second phenotype, observed in four unrelated families, is autosomal dominant trismus-pseudocamptodactyly syndrome (distal arthrogryposis type 7; previously associated exclusively with myosin heavy chain 8 mutations). In all four families, the mutation identified was a novel 3-bp in-frame deletion (c.20_22del) that results in deletion of a conserved lysine at the seventh amino acid position (p.K7del). This is the first mutation identified in the extreme N-terminus of ß-tropomyosin. To understand the potential pathogenic mechanism(s) underlying this mutation, we performed both computational analysis and in vivo modelling. Our theoretical model predicts that the mutation disrupts the N-terminus of the α-helices of dimeric ß-tropomyosin, a change predicted to alter protein-protein binding between ß-tropomyosin and other molecules and to disturb head-to-tail polymerization of ß-tropomyosin dimers. To create an in vivo model, we expressed wild-type or p.K7del ß-tropomyosin in the developing zebrafish. p.K7del ß-tropomyosin fails to localize properly within the thin filament compartment and its expression alters sarcomere length, suggesting that the mutation interferes with head-to-tail ß-tropomyosin polymerization and with overall sarcomeric structure. We describe a novel ß-tropomyosin mutation, two clinical-histopathological phenotypes not previously associated with ß-tropomyosin and pathogenic data from the first animal model of ß-tropomyosin-related myopathies.

Real-World Data on Access to Standards of Care for People With Spinal Muscular Atrophy in the UK.

Spinal Muscular Atrophy (SMA) is characterized by muscle atrophy and weakness and has an incidence of 1:11. 000 live births which projects an estimated population in the UK of 650-1,300 affected patients. Standards of Care (SoC) were updated in 2017 and they have been widely adopted as a reference for implementation of care in SMA across the globe. The effectiveness of implementation and adherence to these standards across different countries is unclear. The aim of this study is to describe the experience of individuals with SMA regarding their care in the UK. An online anonymised survey was sent out via patient organizations, the UK SMA Patient Registry, professional networks, and social media to reach across the UK. The survey captured demographic profile, professionals involved in a patient's care, Interventions and access to mobility aids and home adaptations. Participants responded about their access to services and to rate how important each professional and intervention was for their health and wellbeing. One hundred and twenty-eight responses were collected with a median age of 34 years (1-81). Seventy-three percent of participants were adults and 60% men. Overall good access to neurologist (>90%) but limited to nurse specialist (48%) and physiotherapist (57%). Good access to respiratory support was reported but limited for interventions for positioning and bracing and exercise. This survey highlights that access to certain professionals for people with SMA is limited in the UK. Striking differences were noted between pediatric and adult populations. Limited access to care were regularly reported, with half of the study population consistently not accessing full multidisciplinary care. Access to interventions for contracture management were recorded to have significant limitations. Mobility aids and home adaptations are widely available and were also reported as the most valued interventions. Access to nutritional support or speech and language therapy appears only to be available for a small proportion of the participants. Access to respiratory care was good especially in severe forms of SMA. We found pockets of good practice in the UK that align with the SoC. However, access is not equal for adults and children and access to certain professionals is significantly limited.

Enhanced green fluorescent protein-expressing human mesenchymal stem cells retain neural marker expression.

Mesenchymal stem cells (MSCs) have the potential to play a role in autologous treatment of central nervous system injury or disease. Here we transduced human MSCs with enhanced green fluorescent protein (EGFP). We compared the capacity of control and EGFP-positive cells to proliferate under normal culture conditions, as well as express neural markers following trans-differentiation. EGFP-positive cells proliferated comparably to controls, retained EGFP expression over the course of multiple passages, and retained neural marker expression at levels comparable to control MSCs. Further neurogenic capacity of EGFP-positive human MSCs was examined by growth as neural stem cell-like neurospheres. No significant difference was observed in the ability of control or EGFP-positive cells to generate primary neurospheres or to expand during passage. When examined by immunostaining for the presence of neuroectodermal markers, neurosphere-derived cells similarly expressed neural markers. We show that human MSCs expressing EGFP represent an attractive and practical source of stem cells for the study of repair and regeneration in neurological models.