Lower Extremity Muscle Involvement in the Intermediate and Bethlem Myopathy Forms of COL6-Related Dystrophy and Duchenne Muscular Dystrophy: A Cross-Sectional Study

MRI for the diagnosis of limb girdle muscular dystrophies

PURPOSE OF REVIEW

In the last 30 years, there have many publications describing the pattern of muscle involvement of different neuromuscular diseases leading to an increase in the information available for diagnosis. A high degree of expertise is needed to remember all the patterns described. Some attempts to use artificial intelligence or analysing muscle MRIs have been developed. We review the main patterns of involvement in limb girdle muscular dystrophies (LGMDs) and summarize the strategies for using artificial intelligence tools in this field.

RECENT FINDINGS

The most frequent LGMDs have a widely described pattern of muscle involvement; however, for those rarer diseases, there is still not too much information available. patients. Most of the articles still include only pelvic and lower limbs muscles, which provide an incomplete picture of the diseases. AI tools have efficiently demonstrated to predict diagnosis of a limited number of disease with high accuracy.

SUMMARY

Muscle MRI continues being a useful tool supporting the diagnosis of patients with LGMD and other neuromuscular diseases. However, the huge variety of patterns described makes their use in clinics a complicated task. Artificial intelligence tools are helping in that regard and there are already some accessible machine learning algorithms that can be used by the global medical community.

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Inhibition of discoidin domain receptor (DDR)-1 with nilotinib alters CSF miRNAs and is associated with reduced inflammation and vascular fibrosis in Alzheimer's disease

Discoidin Domain Receptor (DDR)-1 is activated by collagen. Nilotinib is a tyrosine kinase inhibitor that is FDA-approved for leukemia and potently inhibits DDR-1. Individuals diagnosed with mild-moderate Alzheimer's disease (AD) treated with nilotinib (versus placebo) for 12 months showed reduction of amyloid plaque and cerebrospinal fluid (CSF) amyloid, and attenuation of hippocampal volume loss. However, the mechanisms are unclear. Here, we explored unbiased next generation whole genome miRNA sequencing from AD patients CSF and miRNAs were matched with their corresponding mRNAs using gene ontology. Changes in CSF miRNAs were confirmed via measurement of CSF DDR1 activity and plasma levels of AD biomarkers. Approximately 1050 miRNAs are detected in the CSF but only 17 miRNAs are specifically altered between baseline and 12-month treatment with nilotinib versus placebo. Treatment with nilotinib significantly reduces collagen and DDR1 gene expression (upregulated in AD brain), in association with inhibition of CSF DDR1. Pro-inflammatory cytokines, including interleukins and chemokines are reduced along with caspase-3 gene expression. Specific genes that indicate vascular fibrosis, e.g., collagen, Transforming Growth Factors (TGFs) and Tissue Inhibitors of Metalloproteases (TIMPs) are altered by DDR1 inhibition with nilotinib. Specific changes in vesicular transport, including the neurotransmitters dopamine and acetylcholine, and autophagy genes, including ATGs, indicate facilitation of autophagic flux and cellular trafficking. Inhibition of DDR1 with nilotinib may be a safe and effective adjunct treatment strategy involving an oral drug that enters the CNS and adequately engages its target. DDR1 inhibition with nilotinib exhibits multi-modal effects not only on amyloid and tau clearance but also on anti-inflammatory markers that may reduce cerebrovascular fibrosis.

A novel variant of COL6A3 c.6817-2(IVS27)A>G causing Bethlem myopathy: A case report

Bethlem myopathy (BM) is a disease that is caused by mutations in the collagen VI genes. It is a mildly progressive disease characterized by proximal muscle weakness and contracture of the fingers, the wrist, the elbow, and the ankle. BM is an autosomal dominant inheritance that is mainly caused by dominant COL6A1, COL6A2, or COL6A3 mutations. However, a few cases of collagen VI mutations with bilateral facial weakness and Beevor's sign have also been reported. This study presents a 50-year-old female patient with symptoms of facial weakness beginning in childhood and with the slow progression of the disease with age. At the age of 30 years, the patient presented with asymmetrical proximal muscle weakness, and the neurological examination revealed bilateral facial weakness and a positive Beevor's sign. Phosphocreatine kinase was slightly elevated with electromyography showing myopathic changes and magnetic resonance imaging (MRI) of the lower limb muscles showing the muscle MRI associated with collagen VI (COL6)-related myopathy (COL6-RM). The whole-genome sequencing technology identified the heterozygous mutation c.6817-2(IVS27)A>G in the COL6A3 gene, which was in itself a novel mutation. The present study reports yet another case of BM, which is caused by the recessive COL6A3 intron variation, widening the clinical spectrum and genetic heterogeneity of BM.

CRISPR/Cas9-Mediated Allele-Specific Disruption of a Dominant COL6A1 Pathogenic Variant Improves Collagen VI Network in Patient Fibroblasts

Collagen VI-related disorders are the second most common congenital muscular dystrophies for which no treatments are presently available. They are mostly caused by dominant-negative pathogenic variants in the genes encoding α chains of collagen VI, a heteromeric network forming collagen; for example, the c.877G>A; p.Gly293Arg COL6A1 variant, which alters the proper association of the tetramers to form microfibrils. We tested the potential of CRISPR/Cas9-based genome editing to silence or correct (using a donor template) a mutant allele in the dermal fibroblasts of four individuals bearing the c.877G>A pathogenic variant. Evaluation of gene-edited cells by next-generation sequencing revealed that correction of the mutant allele by homologous-directed repair occurred at a frequency lower than 1%. However, the presence of frameshift variants and others that provoked the silencing of the mutant allele were found in >40% of reads, with no effects on the wild-type allele. This was confirmed by droplet digital PCR with allele-specific probes, which revealed a reduction in the expression of the mutant allele. Finally, immunofluorescence analyses revealed a recovery in the collagen VI extracellular matrix. In summary, we demonstrate that CRISPR/Cas9 gene-edition can specifically reverse the pathogenic effects of a dominant negative variant in COL6A1.

Skeletal muscle proteome expression differentiates severity of cancer cachexia in mice and identifies loss of fragile X mental retardation syndrome-related protein 1

TMT-based quantitative proteomics was used to examine protein expression in skeletal muscle from mice with moderate and severe cancer cachexia to study mechanisms underlying varied cachexia severity. Weight loss of 10% (moderate) and 20% (severe) was induced by injection of colon-26 cancer cells in 10-week old Balb/c mice. In moderate cachexia, enriched pathways reflected fibrin formation, integrin/MAPK signaling, and innate immune system, suggesting an acute phase response and fibrosis. These pathways remained enriched in severe cachexia, however, energy-yielding pathways housed in mitochondria were prominent additions to the severe state. These enrichments suggest distinct muscle proteome expression patterns that differentiate cachexia severity. When analyzed with two other mouse models, eight differentially expressed targets were shared including Serpina3n, Sypl2, Idh3a, Acox1, Col6a1, Myoz3, Ugp2, and Slc41a3. Acox1 and Idh3a control lipid oxidation and NADH generation in the TCA cycle, respectively, and Col6a1 comprises part of type VI collagen with reported profibrotic functions, suggesting influential roles in cachexia. A potential target was identified in FXR1, an RNA-binding protein not previously implicated in cancer cachexia. FXR1 decreased in cachexia and related linearly with weight change and myofiber size. These findings suggest distinct mechanisms associated with cachexia severity and potential biomarkers and therapeutic targets. This article is protected by copyright. All rights reserved.