Deep RNA profiling identified CLOCK and molecular clock genes as pathophysiological signatures in collagen VI myopathy.

Collagen VI myopathies are genetic disorders caused by mutations in collagen 6 A1, A2 and A3 genes, ranging from the severe Ullrich congenital muscular dystrophy to the milder Bethlem myopathy, which is recapitulated by collagen-VI-null (Col6a1(-/-)) mice. Abnormalities in mitochondria and autophagic pathway have been proposed as pathogenic causes of collagen VI myopathies, but the link between collagen VI defects and these metabolic circuits remains unknown. To unravel the expression profiling perturbation in muscles with collagen VI myopathies, we performed a deep RNA profiling in both Col6a1(-/-)mice and patients with collagen VI pathology.

Mutations in the collagen XII gene define a new form of extracellular matrix-related myopathy.

Bethlem myopathy (BM) [MIM 158810] is a slowly progressive muscle disease characterized by contractures and proximal weakness, which can be caused by mutations in one of the collagen VI genes (COL6A1, COL6A2 and COL6A3). However, there may be additional causal genes to identify as in ∼50% of BM cases no mutations in the COL6 genes are identified. In a cohort of -24 patients with a BM-like phenotype, we first sequenced 12 candidate genes based on their function, including genes for known binding partners of collagen VI, and those enzymes involved in its correct post-translational modification, assembly and secretion.

Characterization of a rare case of Ullrich congenital muscular dystrophy due to truncating mutations within the COL6A1 gene C-terminal domain: a case report.

Background: Mutations within the C-terminal region of the COL6A1 gene are only detected in Ullrich/Bethlem patients on extremely rare occasions.

Case Presentation: Herein we report two Brazilian brothers with a classic Ullrich phenotype and compound heterozygous for two truncating mutations in COL6A1 gene, expected to result in the loss of the α1(VI) chain C2 subdomain. Despite the reduction in COL6A1 RNA level due to nonsense RNA decay, three truncated alpha1 (VI) chains were produced as protein variants encoded by different out-of-frame transcripts.

Expression of collagen VI α5 and α6 chains in human muscle and in Duchenne muscular dystrophy-related muscle fibrosis.

Collagen VI is a major extracellular matrix (ECM) protein with a critical role in maintaining skeletal muscle functional integrity. Mutations in COL6A1, COL6A2 and COL6A3 genes cause Ullrich Congenital Muscular Dystrophy (UCMD), Bethlem Myopathy, and Myosclerosis. Moreover, Col6a1(-/-) mice and collagen VI deficient zebrafish display a myopathic phenotype.

Macrophages: a minimally invasive tool for monitoring collagen VI myopathies.

Introduction: Collagen VI expression was tested in peripheral blood macrophages from patients with collagen VI-related myopathies and compared with muscle biopsy.

Methods: RNA and protein studies were performed in blood macrophages from 5 patients previously diagnosed with either Ullrich congenital muscular dystrophy (UCMD) or Bethlem myopathy (BM). The full spectrum of possible genotypes was considered, including both dominant and recessive UCMD and BM cases.

Expression of the collagen VI α5 and α6 chains in normal human skin and in skin of patients with collagen VI-related myopathies.

Collagen VI is an extracellular matrix protein with critical roles in maintaining muscle and skin integrity and function. Skin abnormalities, including predisposition to keratosis pilaris and abnormal scarring, were described in Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) patients carrying mutations in COL6A1, COL6A2, and COL6A3 genes, whereas COL6A5, previously designated as COL29A1, was linked to atopic dermatitis. To gain insight into the function of the newly identified collagen VI α5 and α6 chains in human skin, we studied their expression and localization in normal subjects and in genetically characterized UCMD and BM patients.

Identification of a deep intronic mutation in the COL6A2 gene by a novel custom oligonucleotide CGH array designed to explore allelic and genetic heterogeneity in collagen VI-related myopathies.

Background: Molecular characterization of collagen-VI related myopathies currently relies on standard sequencing, which yields a detection rate approximating 75-79% in Ullrich congenital muscular dystrophy (UCMD) and 60-65% in Bethlem myopathy (BM) patients as PCR-based techniques tend to miss gross genomic rearrangements as well as copy number variations (CNVs) in both the coding sequence and intronic regions.

Methods: We have designed a custom oligonucleotide CGH array in order to investigate the presence of CNVs in the coding and non-coding regions of COL6A1, A2, A3, A5 and A6 genes and a group of genes functionally related to collagen VI. A cohort of 12 patients with UCMD/BM negative at sequencing analysis and 2 subjects carrying a single COL6 mutation whose clinical phenotype was not explicable by inheritance were selected and the occurrence of allelic and genetic heterogeneity explored.

Autosomal recessive Bethlem myopathy.

Background: Bethlem myopathy is a well-defined clinical entity among collagen VI disorders, featuring proximal muscle weakness and contractures of the fingers, wrists, and ankles. It is an early-onset, slowly progressive, and relatively mild disease, invariably associated to date with heterozygous dominant mutations in the 3 collagen VI genes. We have characterized the clinical, laboratory, and genetic features of autosomal recessive Bethlem myopathy in 2 unrelated patients.

Identification and characterization of novel collagen VI non-canonical splicing mutations causing Ullrich congenital muscular dystrophy.

Splicing mutations occurring outside the invariant GT and AG dinucleotides are frequent in disease genes and the definition of their pathogenic potential is often challenging. We have identified four patients affected by Ullrich congenital muscular dystrophy and carrying unusual mutations of COL6 genes affecting RNA splicing. In three cases the mutations occurred in the COL6A2 gene and consisted of nucleotide substitutions within the degenerated sequences flanking the canonical dinucleotides.

Cationic PMMA nanoparticles bind and deliver antisense oligoribonucleotides allowing restoration of dystrophin expression in the mdx mouse.

For subsets of Duchenne muscular dystrophy (DMD) mutations, antisense oligoribonucleotide (AON)-mediated exon skipping has proven to be efficacious in restoring the expression of dystrophin protein. In the mdx murine model systemic delivery of AON, recognizing the splice donor of dystrophin exon 23, has shown proof of concept. Here, we show that using cationic polymethylmethacrylate (PMMA) (marked as T1) nanoparticles loaded with a low dose of 2'-O-methyl-phosphorothioate (2'OMePS) AON delivered by weekly intraperitoneal (IP) injection (0.

A novel custom high density-comparative genomic hybridization array detects common rearrangements as well as deep intronic mutations in dystrophinopathies.

Background: The commonest pathogenic DMD changes are intragenic deletions/duplications which make up to 78% of all cases and point mutations (roughly 20%) detectable through direct sequencing. The remaining mutations (about 2%) are thought to be pure intronic rearrangements/mutations or 5'-3' UTR changes. In order to screen the huge DMD gene for all types of copy number variation mutations we designed a novel custom high density comparative genomic hybridisation array which contains the full genomic region of the DMD gene and spans from 100 kb upstream to 100 kb downstream of the 2.

Transcriptional behavior of DMD gene duplications in DMD/BMD males.

DMD gene exons duplications account for up to 5-10 % of Duchenne (DMD) and up to 5-19% of Becker (BMD) muscular dystrophies; as for the more common deletions, the genotype-phenotype correlation and the genetic prognosis are generally based on the "reading frame rule". Nevertheless, the transcriptional profile of duplications, abridging the genomic configuration to the eventual protein effect, has been poorly studied. We describe 26 DMD gene duplications occurring in 33 unrelated patients and detected among a cohort of 194 mutation-positive DMD/BMD patients.

Autosomal recessive myosclerosis myopathy is a collagen VI disorder.

Objective: To determine the clinical and molecular features of a new phenotype related to collagen VI myopathies.

Methods: We examined two patients belonging to a consanguineous family affected by myosclerosis myopathy, screened for mutations of collagen VI genes, and performed a detailed biochemical and morphologic analysis of the muscle biopsy and cultured fibroblasts.

Results: The patients had a novel homozygous nonsense COL6A2 mutation (Q819X); the mutated messenger RNA escaped nonsense-mediated decay and was translated into a truncated alpha2(VI) chain, lacking the sole C2 domain.