VI-related Myopathies Research Articles

COL6A1 related muscular dystrophy in Landseer dogs: A canine model for Ullrich congenital muscular dystrophy.

Collagen VI related myopathies are congenital diseases of variable phenotype. The severe phenotype is referred to as Ullrich congenital muscular dystrophy. In this study, we describe analoguos clinical signs and histopathological alterations in Landseer dogs. We collected clinical data from two affected dogs and investigated the neuromuscular changes in five dogs from two different litters with immunohistochemistry and immunofluorescence. All affected dogs were homozygous for the p.Glu97* nonsense variant in the COL6A1 gene encoding the alpha-1 chain of collagen VI. Muscle biopsies revealed alterations similar to those in human patients with Ullrich congenital muscular dystrophy including the virtual absence of collagen VI in skeletal muscles. The clinical and pathological characterization of the affected Landseer dogs enhances the value of this animal model for human Ullrich congenital muscular dystrophy.

CONGENITAL MUSCULAR DYSTROPHIES: P.193 Collagen VI-related myopathy. Clinical and genetic findings in a large Chilean cohort

Collagen VI related myopathy is one of the more prevalent inherited neuromuscular myopathies. Determining the genetic and clinical features in our population is relevant to improve patients care and develop a platform for collaborative studies and future clinical trials. We describe the phenotype, genotype and muscle MRI (WBMRI) in a series of patients with Collagen VI-Related Myopathy (COLVI-RM). A retrospective study of patients with a genetic diagnosis of Collagen-VI-RM, IRB-approved. Demographic data and patients’ characteristics were obtained from medical records.

Two novel COL6A3 mutations disrupt extracellular matrix formation and lead to myopathy from Ullrich congenital muscular dystrophy and Bethlem myopathy spectrum

Here we present a case report of collagen VI related myopathy in a patient, 8 y.o. boy, with intermediate phenotype between severe Ullrich congenital muscular dystrophy and milder Bethlem myopathy. Whole exome sequencing revealed two novel single nucleotide variants in COL6A3 gene: paternal p.Glu2402Ter, resulting in premature translation termination codon and degradation of mRNA from this allele probably due to nonsense-mediated decay, and maternal p.Arg1660Cys leading to amino-acid substitution in N2-terminal domain. COL6A3 expression analysis of proband's fibroblasts reveals functional homozygosity of the latter variant. Paternal fibroblasts showed only WT allele expression, which could lead to a reduction in mature transcript level, while maternal fibroblasts expressed both alleles. Functional assay of immunofluorescent staining of COL6A3 protein in fibroblasts culture reveals profound changes in COL6A3 localization and reduction of protein level in studied cultures when comparing with the controls. This study not only broadens the allelic spectrum of pathogenic COL6A3 variants in myopathy but also gives an additional support to Ullrich congenital muscular dystrophy and Bethlem myopathy clinical continuum.

P.26 - COL6A genes transcriptomic by RNAseq and fluidic card tools

Mutations in collagen VI A1, A2, and A3 genes cause collagen VI related myopathies, ranging from the severe Ullrich congenital muscular dystrophy (UCMD) to the milder Bethlem myopathy (BM). COL6A1 gene produces a single transcript. COL6A2 gene is transcribed in multiple alternatively spliced mRNAs that differ in the 5'-untranslated region as well as in the 3'-coding and noncoding sequences. COL6A3 transcription is even more complex with various N-terminal exons subjected to multiple alternative splicing. The pattern of isoforms representation in muscle and their functional role has been fairly investigated. Furthermore, COL6A genes mutations affecting splicing are a frequent cause of UCMD-BM phenotypes (around 20% of cases), with genotype-phenotype correlations often unclear. In these cases, non-sense mediated decay of aberrant transcript represents a frequent event, often hampering the detection of mutated transcripts. We have compared two different approaches, RNAseq and a TaqMan® low-density array for Real-Time transcription analysis, for the ability to profile COL6A genes isoforms and to detected mutated transcripts resulting for splicing mutations. RNA-seq was performed on three COL6A mutated patients, carrying either a small in-frame deletion, a mutation expected to induce NMD (homozygous nonsense change) and a canonical splicing mutation. In parallel, the ability of the fluidic card tool to detect splicing mutations and to profile COL6A genes isoforms was also tested in patients and control muscle samples. The RNA-seq turned out to be the optimal strategy, able to pick-up low quantity COL6A genes mRNAs derived both from physiological alternative splicing and from pathogenic mutations. We constructed a RNA-seq based map of COL6A genes isoforms expression in normal and affected muscles.

Differences in Adipose Tissue and Lean Mass Distribution in Patients with Collagen VI Related Myopathies Are Associated with Disease Severity and Physical Ability.

Mutations in human collagen VI genes cause a spectrum of musculoskeletal conditions in children and adults collectively termed collagen VI-related myopathies (COL6-RM) characterized by a varying degree of muscle weakness and joint contractures and which include Ullrich Congenital Muscular Dystrophy (UCMD) and Bethlem Myopathy (BM). Given that collagen VI is one of the most abundant extracellular matrix proteins in adipose tissue and its emerging role in energy metabolism we hypothesized that collagen VI deficiency might be associated with alterations in adipose tissue distribution and adipokines serum profile. We analyzed body composition by means of dual-energy X-ray absorptiometry in 30 pediatric and adult COL6-RM myopathy patients representing a range of severities (UCMD, intermediate-COL6-RM, and BM). We found a distinctive pattern of regional adipose tissue accumulation which was more evident in children at the most severe end of the spectrum. In particular, the accumulation of fat in the android region was a distinguishing feature of UCMD patients. In parallel, there was a decrease in lean mass compatible with a state of sarcopenia, particularly in ambulant children with an intermediate phenotype. All children and adult patients that were sarcopenic were also obese. These changes were significantly more pronounced in children with collagen VI deficiency than in children with Duchenne Muscular Dystrophy of the same ambulatory status. High molecular weight adiponectin and leptin were significantly increased in sera from children in the intermediate and BM group. Correlation analysis showed that the parameters of fat mass were negatively associated with motor function according to several validated outcome measures. In contrast, lean mass parameters correlated positively with physical performance and quality of life. Leptin and adiponectin circulating levels correlated positively with fat mass parameters and negatively with lean mass and thus may be relevant to the disease pathogenesis and as circulating markers. Taken together our results indicate that COL6-RM are characterized by specific changes in total fat mass and distribution which associate with disease severity, motor function, and quality of life and which are clinically meaningful and thus should be taken into consideration in the management of these patients.

Autophagy activation in COL6 myopathic patients by a low-protein-diet pilot trial

ABSTRACTA pilot clinical trial based on nutritional modulation was designed to assess the efficacy of a one-year low-protein diet in activating autophagy in skeletal muscle of patients affected by COL6/collagen VI-related myopathies. Ullrich congenital muscular dystrophy and Bethlem myopathy are rare inherited muscle disorders caused by mutations of COL6 genes and for which no cure is yet available. Studies in col6 null mice revealed that myofiber degeneration involves autophagy defects and that forced activation of autophagy results in the amelioration of muscle pathology. Seven adult patients affected by COL6 myopathies underwent a controlled low-protein diet for 12 mo and we evaluated the presence of autophagosomes and the mRNA and protein levels for BECN1/Beclin 1 and MAP1LC3B/LC3B in muscle biopsies and blood leukocytes. Safety measures were assessed, including muscle strength, motor and respiratory function, and metabolic parameters. After one y of low-protein diet, autophagic markers were increased in skeletal muscle and blood leukocytes of patients. The treatment was safe as shown by preservation of lean:fat percentage of body composition, muscle strength and function. Moreover, the decreased incidence of myofiber apoptosis indicated benefits in muscle homeostasis, and the metabolic changes pointed at improved mitochondrial function. These data provide evidence that a low-protein diet is able to activate autophagy and is safe and tolerable in patients with COL6 myopathies, pointing at autophagy activation as a potential target for therapeutic applications. In addition, our findings indicate that blood leukocytes are a promising noninvasive tool for monitoring autophagy activation in patients.

Transcriptome Analysis of Ullrich Congenital Muscular Dystrophy Fibroblasts Reveals a Disease Extracellular Matrix Signature and Key Molecular Regulators

BackgroundCollagen VI related myopathies encompass a range of phenotypes with involvement of skeletal muscle, skin and other connective tissues. They represent a severe and relatively common form of congenital disease for which there is no treatment. Collagen VI in skeletal muscle and skin is produced by fibroblasts.Aims & MethodsIn order to gain insight into the consequences of collagen VI mutations and identify key disease pathways we performed global gene expression analysis of dermal fibroblasts from patients with Ullrich Congenital Muscular Dystrophy with and without vitamin C treatment. The expression data were integrated using a range of systems biology tools. Results were validated by real-time PCR, western blotting and functional assays.FindingsWe found significant changes in the expression levels of almost 600 genes between collagen VI deficient and control fibroblasts. Highly regulated genes included extracellular matrix components and surface receptors, including integrins, indicating a shift in the interaction between the cell and its environment. This was accompanied by a significant increase in fibroblasts adhesion to laminin. The observed changes in gene expression profiling may be under the control of two miRNAs, miR-30c and miR-181a, which we found elevated in tissue and serum from patients and which could represent novel biomarkers for muscular dystrophy. Finally, the response to vitamin C of collagen VI mutated fibroblasts significantly differed from healthy fibroblasts. Vitamin C treatment was able to revert the expression of some key genes to levels found in control cells raising the possibility of a beneficial effect of vitamin C as a modulator of some of the pathological aspects of collagen VI related diseases.

Utility of next generation sequencing in genetic diagnosis of early onset neuromuscular disorders

BackgroundNeuromuscular disorders are a clinically, pathologically, and genetically heterogeneous group. Even for the experienced clinician, an accurate diagnosis is often challenging due to the complexity of these disorders. Here, we...

Col6a1 null mice as a model to study skin phenotypes in patients with collagen VI related myopathies: expression of classical and novel collagen VI variants during wound healing.

Patients suffering from collagen VI related myopathies caused by mutations in COL6A1, COL6A2 and COL6A3 often also display skin abnormalities, like formation of keloids or “cigarette paper” scars, dry skin, striae rubrae and keratosis pilaris (follicular keratosis). Here we evaluated if Col6a1 null mice, an established animal model for the muscle changes in collagen VI related myopathies, are also suitable for the study of mechanisms leading to the skin pathology. We performed a comprehensive study of the expression of all six collagen VI chains in unwounded and challenged skin of wild type and Col6a1 null mice. Expression of collagen VI chains is regulated in both skin wounds and bleomycin-induced fibrosis and the collagen VI α3 chain is proteolytically processed in both wild type and Col6a1 null mice. Interestingly, we detected a decreased tensile strength of the skin and an altered collagen fibril and basement membrane architecture in Col6a1 null mice, the latter being features that are also found in collagen VI myopathy patients. Although Col6a1 null mice do not display an overt wound healing defect, these mice are a relevant animal model to study the skin pathology in collagen VI related disease.

173rd ENMC international workshop: Congenital muscular dystrophy outcome measures 5–7 March 2010, Naarden, The Netherlands

The 173rd ENMC/TREAT-NMDworkshop on congenital muscular dystrophy (CMD) outcome measures is the 9th CMD workshop, beginning in 1993 with the establishment of a CMD consortium. The workshop brought together 22 clinicians and experts from five countries to advance the implementation of suitable clinical outcome measures and endpoints specific for the CMDs to advance CMD clinical trial readiness. The CMDs are a genetically diverse group of early onset disorders of muscle with dystrophic features in the muscle biopsy. The core genetic groups currently subsumed under the CMDs are the collagen VI related myopathies Ullrich and Bethlem, laminin alpha 2 deficient CMD, the alpha-dystroglycan related CMDs (dystroglycanopathies) and SEPN1 related myopathy (Rigid Spine CMD). Despite the genetic heterogeneity, the clinical problems posed by these conditions are sufficiently interrelated to justify developing an integrated diagnostic, management and therapeutic development approach across CMD forms. Such a unified approach for the CMDs has resulted recently in the launch of an international CMD registry (CMDIR) and a parallel effort to delineate CMD consensus care and diagnostic guidelines, as necessary steps towards the implementation of future CMD clinical trials. The workshop focused on three specific goals: to identify clinically relevant functional classes within the individual CMD subtypes that could be combined for the purpose of clinical outcomes; to review currently available motor scales for their suitability for the functional classes and specific subtypes and to outline CMD common data elements

P1.13 Pathological spectrum of collagen VI related myopathies: Does the pathology tell us something about the disease?

Ullrich Congenital Muscular Dystrophy (UCMD) and Bethlem myopathy are caused by mutations in collagen VI genes. Most mutations result in partial reduction of collagen VI but in some cases collagen VI is not visibly reduced. UCMD is one of the most common forms of congenital muscular dystrophy and the clinical and pathological spectrums are wider than anticipated. Here we summarise the histopathological findings in a series of cases with mutations in COL6A genes spanning the clinical spectrum.

EM.P.4.01 Collagen VI related myopathies: Exploring the phenotypic spectrum

EM.P.4.01 Collagen VI related myopathies: Exploring the phenotypic spectrum

G.P.6.03 Specific CT scanner muscle pattern helps to differentiate contractural lamin A/C and collagen VI related myopathies

G.P.6.03 Specific CT scanner muscle pattern helps to differentiate contractural lamin A/C and collagen VI related myopathies