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Open Access Review

ColVI myopathies: where do we stand, where do we go?

Valérie Allamand1234*, Laura Briñas1234, Pascale Richard5, Tanya Stojkovic12346, Susana Quijano-Roy7 and Gisèle Bonne12345

Author Affiliations

1 Inserm, U974, Paris, France

2 CNRS, UMR7215, Paris, France

3 UPMC Univ Paris 06 UM76, IFR14, Paris, France

4 Institut de Myologie, Paris, France

5 AP-HP, Groupe Hospitalier Pitié-Salpêtrière, UF Cardiogénétique et Myogénétique, Service de Biochimie Métabolique, Paris, France

6 Centre de Référence Neuromusculaire Paris-Est, Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France

7 AP-HP, Service de Pédiatrie, Centre de Référence Maladies Neuromusculaires (GNMH) Hôpital Raymond Poincaré, Garches, France

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Skeletal Muscle 2011, 1:30  doi:10.1186/2044-5040-1-30

The electronic version of this article is the complete one and can be found online at: http://www.skeletalmusclejournal.com/content/1/1/30


Received:24 March 2011
Accepted:23 September 2011
Published:23 September 2011

© 2011 Allamand et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), represent a clinical continuum with Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) at each end of the spectrum, and less well-defined intermediate phenotypes in between. ColVI myopathies also share common features with other disorders associated with prominent muscle contractures, making differential diagnosis difficult. This group of disorders, under-recognized for a long time, has aroused much interest over the past decade, with important advances made in understanding its molecular pathogenesis. Indeed, numerous mutations have now been reported in the COL6A1, COL6A2 and COL6A3 genes, a large proportion of which are de novo and exert dominant-negative effects. Genotype-phenotype correlations have also started to emerge, which reflect the various pathogenic mechanisms at play in these disorders: dominant de novo exon splicing that enables the synthesis and secretion of mutant tetramers and homozygous nonsense mutations that lead to premature termination of translation and complete loss of function are associated with early-onset, severe phenotypes. In this review, we present the current state of diagnosis and research in the field of ColVI myopathies. The past decade has provided significant advances, with the identification of altered cellular functions in animal models of ColVI myopathies and in patient samples. In particular, mitochondrial dysfunction and a defect in the autophagic clearance system of skeletal muscle have recently been reported, thereby opening potential therapeutic avenues.

Review

Collagen VI: an important component of connective tissues

Collagens are major constituents of the extracellular matrix (ECM), and are found in most connective tissues. They provide structural and mechanical stability to tissues, but they also play crucial roles in cell-ECM interactions through various receptors [1]. In particular, collagen type VI (ColVI), an important component of skeletal muscle ECM, is involved in maintaining tissue integrity by providing a structural link between different constituents of connective-tissue basement membranes (for example, collagen types I and IV, biglycan, and decorin) and cells [2-15] (Figure 1). In addition to its structural role, ColVI supports adhesion, spreading and migration of cells, and cell survival, as discussed later in this review.

thumbnailFigure 1. Schematic representation of the collagen type VI (ColVI) intracellular assembly process, and interactions with skeletal muscle extracellular matrix (ECM) components. Individual α(VI) chains fold through their triple helical domains to form monomers (1:1:1 ratio) in the endoplasmic reticulum (ER), which further align in an anti-parallel manner as dimers and tetramers that are stabilized by disulfide bonds between cysteine residues (S = S links). Post-translational modifications (indicated in orange) take place in the ER and Golgi, followed by secretion of tetramers that align non-covalently end to end, to form beaded microfibrils in the ECM. ColVI interacts with collagenous and non-collagenous components of the basal lamina and interstitial matrix surrounding muscle fibers.

ColVI is a heterotrimeric molecule composed of three individual α(VI) chains that display a similar structure, with a triple helical domain characterized by the repetition of the Gly-X-Y amino acid sequence, flanked by globular domains homologous to von Willebrand factor A domains [16,17]. In addition to the well-known α1(VI), α2(VI) and α3(VI) chains encoded in human by the COL6A1, COL6A2 (located head-to-tail on chromosome 21q22.3), and COL6A3 (on chromosome 2q37) genes [18], three novel chains, α4(VI), α5(VI) and α6(VI), have recently been identified [19,20]. These chains have high structural homology to the α3(VI) chain. In humans, the COL6A4, COL6A5 and COL6A6 genes are all located on chromosome 3q22.1, with the COL6A4 gene being split by a chromosome break and thus not coding for a protein [19-21]. The murine orthologs of these genes are organized in tandem on chromosome 9 (Col6a4, Col6a5 and Col6a6) and encode the α4(VI), α5(VI) and α6(VI) chains. The expression pattern of the three novel chains differs between mice and humans, and also between fetal and adult tissues [19,20]. Importantly, in the context of ColVI myopathies, the α6(VI) chain is the only one expressed at high levels in human skeletal muscle, at higher levels in fetal than adult tissue [19]. In skin, a detailed analysis of the expression of the human α5(VI) and α6(VI) chains revealed that both chains are expressed, albeit differently, and that they are variably altered in tissues from patients with mutations in the COL6A1, COL6A2 and COL6A3 genes [22]. Interestingly, the COL6A5 gene had previously been reported as associated with atopic dermatitis under the name COL29A1 [23], but this association has recently been questioned [24,25]. The knee osteoarthritis susceptibility locus DVWA was shown to correspond to the 5' part of the split COL6A4 gene [21].

Although largely ubiquitous, the expression of ColVI seems to be finely regulated in different cell types and tissues, as shown for the murine Col6a1 gene. The identification of a transcriptional enhancer located in the 5'-flanking sequence of the gene points to a collaborative crosstalk between myogenic and mesenchymal/endomysial cells, enabling transcription of ColV in muscle connective tissue [26-28].

The α1(VI), α2(VI) and α3(VI) chains assemble intracellularly as monomers (1:1:1 ratio), from their C-terminal ends, and subsequently form dimers (two anti-parallel, overlapping monomers) and tetramers (four monomers) that are stabilized by disulfide bonds between cysteine residues of the three chains [29-34]. ColVI chains are subjected to extensive post-translational modifications such as hydroxylation of lysine and proline residues [35], and glycosylation of hydroxylysines, which have been shown to be essential for the tetramerization and further secretion of ColVI [36,37]. Upon secretion, tetramers are further aligned end to end as microfibrils in the extracellular space, with a characteristic beaded appearance [33] (Figure 1). To date, somewhat contradictory results have been obtained regarding the possible assembly of the newly characterized α(VI) polypeptides with the α1(VI), α2(VI) chains. In transfection experiments, only α4(VI) appeared to have this ability [19], whereas in mouse muscle, all three were reported to do so [20]. Whether and how these additional chains may fit in the pathogenesis of ColVI myopathies remains unresolved to date, and needs to be addressed more comprehensively. To date, in our cohort of patients, no pathogenic mutations have been found by sequencing of the COL6A5 and COL6A6 genes in patients without mutations in the COL6A1-3 genes (V. Allamand, data not shown).

Clinical phenotypes of collagen VI myopathies

The etiological definition of ColVI myopathies as a specific condition has evolved over the years with the blurring of boundaries between two disorders, initially described separately but now recognized as the extreme ends of a continuous clinical spectrum [38,39] (Figure 2). The severe endpoint of this spectrum corresponds to Ullrich congenital muscular dystrophy (UCMD, OMIM 254090; http://www.ncbi.nlm.nih.gov/omim webcite), described in 1930 as 'congenital atonic-sclerotic muscular dystrophy', emphasizing its early onset and the presence of proximal joint contractures associated with a striking distal hyperlaxity [40,41]. Orthopedic deformities (joint contractures, scoliosis) and respiratory impairment with diaphragmatic failure generally develop within the first decade of life, and may be life-threatening. Arrest of motor milestones with no acquisition of walking ability is seen in a subset of patients, but most children are able to walk, and show later progression of muscle weakness with loss of ambulation around 10 years of age, and a requirement for mechanical ventilation in late childhood or young adulthood [42,43].

thumbnailFigure 2. Clinical spectrum, associated spine deformation and muscle MRI in collagen type VI (ColVI) myopathies. (A), Early severe phenotypes, corresponding to classic Ullrich congenital muscular dystrophy (UCMD), (B) intermediate forms seen in children or adults and (C) less severe, classic Bethlem myopathy (BM) forms constitute the overlapping clinical presentations of ColVI myopathies. (D) Radiography showing the evolution of spine deformation in a patient presenting with a classic early-onset UCMD phenotype. T1 transverse section of Bethlem myopathy upper limb girdle (E) and (F) thighs. Note the fatty infiltration, which appears as hyperintense area on T1-weighted images, located around the triceps brachialis muscles in (E) and along the fascia of vastus lateralis and vastus medialis muscles in (F) (yellow arrows). (G) The concentric fatty involvement of the thigh muscles is also seen on whole body MRI. (Images courtesy of Drs Susana Quijano-Roy and Tanya Stojkovic).

At the other end of the spectrum is the milder form Bethlem myopathy (BM, OMIM 158810), described in 1976, which begins in the first or second decade, although a neonatal history may be recognized, characterized by early contractures of finger flexors, wrist, elbows and ankles [44,45]. Respiratory failure and distal hyperlaxity are usually absent or are milder than in UCMD, although the latter may not be so uncommon in very young children with BM. The course is usually slow, with most of the patients remaining ambulatory. However, progression of muscle weakness occurs often in the fifth decade, resulting in about 50% of patients requiring walking aids or a wheelchair [46]. Intermediate phenotypes have been described, and named 'mild UCMD' or 'severe BM', thereby reinforcing the notion of clinical overlap between Ullrich and Bethlem phenotypes [38,39].

Skin features such as follicular hyperkeratosis and hypertrophic scars or keloid formation are common [38,39,42,43,47-49]. Other common findings include normal cognitive abilities, normal or only slightly raised serum creatine kinase (CK) levels, and absence of cardiac phenotype. Two other conditions that fall within the spectrum of ColVI myopathies have been documented: autosomal dominant limb-girdle muscular dystrophy (LGMD) (in three families) and, more recently, autosomal recessive myosclerosis myopathy (OMIM 255600) (in one family) [50,51].

The prevalences of UCMD and BM in northern England has recently been reported as 0.13 and 0.77 per 100,000, respectively, amounting collectively to 0.9 per 100,000 [52]. UCMD seems to be the second most common type of congenital muscular dystrophy (CMD) in Europe (behind laminin α2 chain deficiency; OMIM 607855) and also in Japan (behind Fukuyama congenital muscular dystrophy; OMIM 253800, [53]) and Australia (behind α-dystroglycan glycosylation defects; [54]). In the cohort from northern England, BM emerges as the fourth most common myopathy behind myotonic dystrophy (OMIM 160900), facio-scapulo-humeral muscular dystrophy (OMIM 158900) and Duchenne/Becker muscular dystrophy (OMIM 310200 and 300376) [52].

Differential diagnosis of ColVI-related myopathies

With the most prominent clinical presentation of ColVI myopathies being muscle weakness and contractures, associated with variable degrees of hyperlaxity, an important difficulty lies in defining boundaries and contiguities, with the possible differential diagnosis including congenital myopathies, Emery-Dreifuss muscular dystrophy (EDMD; OMIM 181350), LGMD, rigid spine muscular dystrophies, and other diseases of connective tissues such as Ehlers-Danlos syndrome [55-57]. Imaging techniques, such as computed tomography or magnetic resonance imaging (MRI) of muscle, are now recognized as very helpful in the diagnostic approach of muscle disease, because there are specific patterns of muscle involvement in each of these contractile myopathies as reported for EDMD with LMNA mutations [58], muscular dystrophies with rigidity of the spine [59], and ColVI myopathies [58,60,61]. From these studies, the typical pattern of muscle involvement in ColVI myopathies is now considered to be constituted by a diffuse, concentric hypodensity of the thigh muscles with relative sparing of the sartorius, gracilis and adductor longus muscles. The vasti muscles are the most affected muscles. In addition, a peculiar central area of abnormal signal is seen within the rectus femoris, initially referred to as a 'central shadow' [62].

In the context of the differential diagnosis, the absence of raised CK levels, the lack of a cardiac phenotype, and the presence of a specific MRI pattern are strongly suggestive of a ColVI myopathy.

Molecular diagnosis and genetics

In light of the clinical variability and the overlapping presentation with other muscular disorders, a definite diagnosis can only be made after the identification of pathogenic mutations in one of the COL6A genes, which to date are restricted to COL6A1, COL6A2 and COL6A3. However, the large size (106 coding exons in total corresponding to 150 kb of genomic DNA) of these genes makes routine molecular diagnostics costly and time-consuming. The road to this 'holy grail' of diagnosis is thus often lengthy and full of pitfalls, and relies on a combination of clinical, biochemical and molecular findings.

Historically, muscle biopsies were the routine and primary step undertaken for diagnostic purposes, and double immunostaining with a basement-membrane marker enabled recognition of ColVI deficiency in patients with UCMD [63], but not in patients with BM. The current diagnostic method of determining ColVI involvement is primarily based on immunocytochemistry of cultured skin fibroblasts, but this analysis is only available in a limited number of laboratories to date. A number of antibodies recognizing human ColVI are now commercially available and may be used for such techniques; in particular, the refined protocol proposed by Hicks et al.[64], using a polyclonal antibody raised against mature ColVI from human placenta, has better sensitivity, especially in fibroblast cultures from patients with BM (Figure 3). The absence or alteration of ColVI secretion in cultured fibroblasts, associated with clinical symptoms compatible with a diagnosis of ColVI myopathy, certainly warrants further genetic analysis.

thumbnailFigure 3. Collagen type VI (ColVI) expression study in cultured skin fibroblasts. (A) Representative images obtained using the protocol from [67] in which ColVI (red) is labeled with monoclonal antibody MAB1944 (Chemicon (now Millipore), Billerica, MA, USA) and perlecan (green) with monoclonal antibody MAB1948 (Chemicon). Note that ColVI expression appeared clearly altered in a patient with an early severe (ES) form and less so in patients with intermediate (Int) or Bethlem myopathy (BM) forms, compared with control fibroblasts (Cont). (B) Using the protocol of Hicks et al. [64], which detects ColVI (red) with polyclonal antibody Ab6588 (Abcam, Cambridge, UK) and fibronectin (green) with monoclonal antibody F15 (Sigma Chemical Co., St Louis, MO, USA), the sensitivity of the method is increased, and defective ColVI secretion could be detected in all patients' samples. Insets indicate nuclei, labeled using DAPI. Bars are 50 μm. (Images courtesy of Corine Gartioux and Valérie Allamand).

Over the past decade, the development of genetic studies has demonstrated the heterogeneity and complexity of the molecular mechanisms at play in ColVI myopathies. An autosomal recessive pattern of inheritance was initially thought to be involved in UCMD, and linkage analysis led to the identification of mutations in the COL6A2 and COL6A3 genes [65-67]. However, numerous dominant de novo mutations have now been shown to be involved, accounting for more than 50% of the mutations causing UCMD [38,39,42,68]. Similarly, autosomal dominant mutations were first identified in the COL6A1 and COL6A2 genes in families with BM, suggesting that BM was mostly familial and inherited as an autosomal dominant disease [69], although rare de novo mutations and autosomal recessive mutations have now been reported [70-73]. To date, over 200 mutations have been identified in these genes, mostly distributed in the COL6A1 and COL6A2 genes. The most common types of mutations are point mutations, and mutations leading to premature termination codons (PTCs) and exon skipping (Figure 4). Among the former, missense changes affecting glycine residues in the triple helical domains of the corresponding proteins are the most common, and are often dominant de novo. Because these changes affect crucial amino acids within the collagenous domains, they hamper triple-helix formation [74-77]. Splice mutations resulting in in-frame exon skipping are generally dominant de novo mutations, and exons 16 of COL6A3 and 14 of COL6A1 seem to be preferentially affected, leading to UCMD or BM phenotypes, respectively [53,75,78-83]. Nonsense mutations and small deletions or insertions inducing PTCs within the coding frame are mostly inherited as recessive mutations, and lead to loss of function of the protein [42,53,68,75,76,79-92]. These mutations are responsible for most UCMD phenotypes. Nevertheless, it should be noted that genotype-phenotype correlations are very difficult to identify.

thumbnailFigure 4. Repartition of the various types of mutations identified in the COL6A1, COL6A2 and COL6A3 genes. This schematic reflects, to the best of our ability, the distribution of 258 allelic mutations (98 on COL6A1, 113 on COL6A2 and 47 on COL6A3). Dominant de novo mutations represent 67% of the missense mutations, affecting glycine residues in the TH domains (Gly in TH), 57% of small deletions (< 5 amino acids) and 44% of splice-site mutations leading to in-frame exon skipping, whereas 97% of mutations leading to premature termination codons (PTCs) are familial (recessive or dominant).

It has recently been shown that all types of mutations alter transcript levels, and that in the case of PTC-bearing transcripts, which are specifically degraded via the nonsense-mediated mRNA decay (NMD [93,94]) pathway, quantification of the three COL6A mRNAs is a helpful tool to pinpoint the mutated gene, thereby facilitating these cumbersome molecular analyses [42]. The NMD-induced degradation of PTC-bearing transcripts may also, at least in part, explain why the parents of patients with UCMD who themselves harbor recessive mutations are asymptomatic; their heterozygous status sustains the expression of 50% of the 'normal' protein, thereby leading to a 'functional loss of heterozygosity'. The study by Briñas and collaborators also provided some genotype-phenotype correlations in a cohort of patients with early-onset ColVI myopathy, showing that recessive mutations leading to PTC were associated with severe phenotypes [42]. Genetic studies are further complicated by a possibly variable penetrance as reported by Peat et al. [89].

Finally, the highly polymorphic nature of the COL6A genes makes it difficult to definitely assign pathogenicity to some variants, especially missense ones that do not affect glycine residues within the triple-helix domains of the proteins. In addition, these 'polymorphisms' may very well play a role in the extreme clinical variability of these conditions, particularly in patients carrying identical mutations but presenting with variable severity.

The types of mutations identified also reflect the methods used in laboratories performing these analyses (for example, sequencing of genomic DNA or of the coding sequences on cDNA), but the emergence of high-throughput methods (arrays) is likely to allow the identification of as yet unknown or under-recognized pathogenic mechanisms, such as large gene rearrangements, or promoter or deep intronic mutations, as recently illustrated in two reports [95,96].

Animal models and pathophysiology

Limited access to muscle biopsies hinders extensive investigations of the specific cellular mechanisms leading to the development of the muscle pathology, and in vitro/ex vivo cellular systems only partially reproduce the complexity of the tissue. The development of the first animal model of ColVI deficiency in 1998, engineered by invalidating the Col6a1 gene in mice, has proven central to understanding the cellular pathways involved in these diseases. Homozygous animals were reported to develop a mild myopathic phenotype, and were initially described as a model of BM [97]. Interestingly, the diaphragm was the most affected muscle, with signs of necrosis evidenced by uptake of Evan's blue dye [97]. Subsequently, a latent mitochondrial dysfunction accompanied by ultrastructural alterations of mitochondria and the sarcoplasmic reticulum, resulting in spontaneous apoptosis, was found in about one-third of muscle fibers [98]. Reduced contractile strength of the diaphragm and other muscle groups was also reported in Col6a1-/- mice in this initial study [98]. The maximal isometric tension generated by ColVI-deficient skinned fibers from gastrocnemius was found to be reduced in a recent report; however, using a protocol of eccentric contractions in vivo, no muscle force drop was found, indicating that the lack of ColVI does not impair myofibrillar function [99]. Importantly, mitochondrial dysfunction was also reported in cultured muscle cells from patients and could be reversed by cyclosporin (Cs)A, an immunosuppressive drug that prevents the opening of the mitochondrial permeability transition pore through binding to cyclophilin D, and also inhibits the phosphatase calcineurin [100,101]. Another in vitro study showed that patients-derived skin fibroblasts behave differently from myoblasts in that respect, and also questioned the specificity of this mitochondrial dysfunction [102], warranting further studies on the matter.

A role for cell survival had previously been proposed for ColVI because it was shown to prevent anti-α1 integrin-mediated apoptosis and trigger the downregulation of bax, a pro-apoptotic molecule [103,104].

Recently, a study of the autophagic process in muscles of Col6a1 knockout mice revealed that autophagy was not induced efficiently [105]. The ensuing defective autophagy provides the link between the previously described mitochondrial dysfunction and myofiber degeneration, as abnormal organelles and molecules cannot be efficiently cleared from the cell. This study further showed that the forced induction of autophagy, either by dietary restriction or by treatment with rapamycin or CsA, ameliorated the phenotype of the Col6a1-/- mice (Figure 5). A similar alteration of autophagy was also detected in muscle biopsies derived from nine patients with UCMD or BM [105]. These data thus provide a basis for novel therapeutic targets to promote the elimination of defective organelles in ColVI-deficient skeletal muscle.

thumbnailFigure 5. Current pathological hypotheses and therapeutic targets. The currently known cascade of main events leading to myofiber degeneration in ColVI-deficient skeletal muscle is shown. Mitochondrial dysfunction (due in part to the defective permeability transition pore (PTP) opening) triggers an energetic imbalance with the increased levels of phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK), Ca2+ overload and the production of reactive oxygen species (ROS). Lack of autophagy induction exacerbates the cellular dysfunction because defective mitochondria and proteins (such as p62 aggregates) are not cleared from the cytoplasm. Together, these defects lead to increased apoptosis. Potential therapeutic interventions are indicated in green.

Morpholino-mediated knock-down of the col6a1 and col6a3 genes in zebrafish embryos showed that collagen VI deficiency significantly impairs muscle development and function [106]. Increased apoptosis, partially prevented by CsA treatment, was also described in the zebrafish morphants [106]. As in other instances, perturbation of muscle components leads to a more severe phenotype in zebrafish than in mouse models, which may in part be due to intrinsic differences in muscle development in these species, especially in terms of timing. Zebrafish models have emerged as major in vivo models of neuromuscular disorders, and seem to be particularly well suited for whole-organism screens for potential pharmacological treatments, as recently illustrated in zebrafish models of Duchenne muscular dystrophy [107].

Therapeutic intervention

To date, no curative treatment exists for these disorders, and most patients rely on supportive treatment of symptoms, usually involving orthopedic (spinal deformations, contractures) and respiratory complications [108].

The unveiling of mitochondrial dysfunction led to an open pilot trial in five patients with UCMD or BM treated orally with CsA for 1 month [109]. This study reported normalization of the mitochondrial dysfunction and decrease of apoptosis of muscle cells following this short-term treatment [110,111]. Longer treatment (up to 2 years) had some beneficial effect on muscle function in these patients but did not prevent progression of the disease in the children [38]. Debio-025 (D-MeAla3EtVal4-cyclosporin; DebioPharm) prevents the inappropriate opening of the mitochondrial permeability transition pore (PTP) without interfering with calcineurin [112], and was shown to restore mitochondrial function in cultured muscle cells of patients [100] and in Col6a1-/- mice [113]. Debio-025 is currently being tested in a phase II clinical trial in patients with chronic hepatitis C. Another anti-apoptotic pharmacological agent that is being investigated in the context of ColVI myopathies is Omigapil (N-(dibenz(b, f)oxepin-10-ylmethyl)-N-methyl-N-prop-2-ynylamine maleate; Santhera Pharmaceuticals), a chemical derivative of (-)-deprenyl, which was shown to reduce GAPDH-Siah1-mediated apoptosis in a mouse model of laminin α2 chain deficiency [114].

It should be noted that translating some of this research from animal models to patients represents a challenging task, particularly because, to date, these drugs have not been approved for use in children, the patient population with the most severe forms of ColVI myopathies. In addition, there is concern about these therapeutic approaches because of the pleiotropic, and potentially harmful, consequences of anti-apoptotic and/or pro-autophagy treatments. Furthermore, such approaches aiming at modulating downstream pathways would not address the primary defect in these disorders, that is, lack of ColVI in the connective tissue, and would thus need to be continually administered. For the sake of discussion, several alternative, and not necessarily exclusive, therapeutic avenues that would sustain re-expression of ColVI may be envisioned. These approaches may consist of gene-based therapies, such as vector delivery of ColVI-coding sequence, and antisense inhibition of mutant transcripts exerting dominant-negative effects [96]. Additionally, as nonsense mutations leading to PTCs are often associated with early-onset, severe phenotypes [42], pharmacological approaches aiming to 'force' translation of PTCs (a phenomenon known as 'translational readthrough' [115]) may prove beneficial for a subset of patients carrying these types of mutations. However, the complex assembly process and regulation of ColVI may prove challenging and may limit the realistic options to be investigated.

Conclusions

The past decade of research on neuromuscular disorders has proven very exciting, and has seen ColVI myopathies emerge as an important set of disorders, rather under-recognized until recently. Many challenges remain despite the tremendous advances in the understanding of their genetic, biochemical and pathophysiological bases. It is hoped that the decade(s) to come will see the development of safe and efficient therapies for these disorders. Consequently, as for other rare diseases, the scientific community, and patient organizations, and patients and their families have become increasingly aware of the need for databases, both clinical and genetic, to facilitate recruitment of patients for upcoming clinical trials.

List of abbreviations used

BM: Bethlem myopathy; ColVI: collagen type VI; COL6A: gene(s) encoding the alpha chain(s) of collagen VI; CsA: cyclosporin A; DAPI: 4',6-diamidino-2-phenylindole; EDMD: Emery-Dreifuss muscular dystrophy; EDS: Ehlers-Danlos syndrome; LMNA: gene encoding lamin A/C; MDC1A: congenital muscular dystrophy with laminin α2 chain deficiency; PTP: permeability transition pore; MRI: magnetic resonance imaging; PTC: premature termination codon; ROS: reactive oxygen species; SEPN1: gene encoding selenoprotein N; TNXB: gene encoding tenascin-X; UCMD: Ullrich congenital muscular dystrophy

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

All authors contributed to the writing of this manuscript. All authors read and approved the final manuscript.

Authors' information

Valérie Allamand holds a PhD in Human Genetics, and currently leads a group focusing on ColVI myopathies in the research unit directed by Thomas Voit. In 2009, she co-organized, with Drs Kate Bushby and Luciano Merlini, the 166th ENMC International Workshop on Collagen Type VI-Related Myopathies (22-24 May 2009, Naarden, The Netherlands). She is the genetic curator of the UMD-COL6 databases, developed in the context of the Treat-NMD European network of excellence.

Laura Briñas obtained her PhD in Molecular Biology. She joined the Institut de Myologie in September 2006 as a post-doctoral fellow, and has been involved in the molecular analysis of mutations in the genes encoding collagen VI and the dissection of their cellular consequences.

Susana Quijano-Roy is a child neurologist with previous medical training in La Paz Hospital (Madrid, Spain) and Boston Children's Hospital (USA). She has held a clinical practice since 2001 at Garches Neuromuscular Reference Center (GNMH), and leads the pediatric EMG laboratory at Necker Enfants Hospital, Paris. She obtained her PhD in 2004 with a study on congenital muscular dystrophies (CMDs). She is part or the international expert group that is currently defining diagnosis, standards of care and natural history of CMDs and establishing outcome measures for future therapeutic trials.

Tanya Stojkovic is a medical doctor, specialized in neurophysiology and neuromuscular disorders. She has worked in the neuromuscular clinical unit directed by Professor Eymard since 2006 (Pitié-Salpêtière, Institut de Myologie, Paris, France). She is involved, as a clinician, in the diagnosis of neuromuscular disorders. She has a special interest in ColVI-related myopathies.

Pascale Richard holds a PharmD, Graduation from Medical Biologist and a PhD in molecular genetics. She is head of the 'Functional Unit of Molecular Cardiogenetics and Myogenetics' at Pitié-Salpêtrière Hospital in Paris, where she developed a functional unit focused on the molecular diagnosis of cardiomyopathies and congenital and progressive myopathies in close collaboration with the research units. This unit constitutes the only laboratory in France where the genetic diagnosis of ColVI myopathies is proposed.

Gisèle Bonne holds a PhD in developmental physiology, followed by a post-doctoral training in human genetics. She currently leads the team 'Genetics and Pathophysiology of Neuromuscular Disorders' in the research unit directed by Thomas Voit at the Institut de Myologie in Paris. Her research group focuses on neuromuscular disorders caused by mutations in the lamin A/C gene.

Acknowledgements

We thank Corine Gartioux and Céline Ledeuil for excellent technical skills. This study was funded by the Institut National de la Santé et de la Recherche Médicale (Inserm), Association Française contre les Myopathies (AFM), UPMC Université Paris 06, Centre National de la Recherche Scientifique (CNRS), Assistance Publique-Hôpitaux de Paris (AP-HP). We apologize to all colleagues who might have not been cited in this review due to space limitations.

References

  1. Leitinger B, Hohenester E: Mammalian collagen receptors.

    Matrix Biol 2007, 26:146-155. PubMed Abstract | Publisher Full Text OpenURL

  2. Bidanset D, Guidry C, Rosenberg L, Choi H, Timpl R, Hook M: Binding of the proteoglycan decorin to collagen type VI.

    J Biol Chem 1992, 267:5250-5256. PubMed Abstract | Publisher Full Text OpenURL

  3. Bonaldo P, Russo V, Bucciotti F, Doliana R, Colombatti A: Structural and functional features of the alpha 3 chain indicate a bridging role for chicken collagen VI in connective tissues.

    Biochemistry 1990, 29:1245-1254. PubMed Abstract | Publisher Full Text OpenURL

  4. Burg MA, Tillet E, Timpl R, Stallcup WB: Binding of the NG2 proteoglycan to type VI collagen and other extracellular matrix molecules.

    J Biol Chem 1996, 271:26110-26116. PubMed Abstract | Publisher Full Text OpenURL

  5. Doane KJ, Yang G, Birk DE: Corneal cell-matrix interactions: type VI collagen promotes adhesion and spreading of corneal fibroblasts.

    Exp Cell Res 1992, 200:490-499. PubMed Abstract | Publisher Full Text OpenURL

  6. Heino J: The collagen family members as cell adhesion proteins.

    BioEssays 2007, 29:1001-1010. PubMed Abstract | Publisher Full Text OpenURL

  7. Keene D, Engvall E, Glanville R: Ultrastructure of type VI collagen in human skin and cartilage suggests an anchoring function for this filamentous network.

    J Cell Biol 1988, 107:1995-2006. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  8. Kielty CM, Whittaker SP, Grant ME, Shuttleworth CA: Type VI collagen microfibrils: evidence for a structural association with hyaluronan.

    J Cell Biol 1992, 118:979-990. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  9. Kuo H-J, Maslen CL, Keene DR, Glanville RW: Type VI collagen anchors endothelial basement membranes by interacting with Type IV collagen.

    J Biol Chem 1997, 272:26522-26529. PubMed Abstract | Publisher Full Text OpenURL

  10. McDevitt CA, Marcelino J, Tucker L: Interaction of intact type VI collagen with hyaluronan.

    FEBS Letters 1991, 294:167-170. PubMed Abstract | Publisher Full Text OpenURL

  11. Pfaff M, Aumailley M, Specks U, Knolle J, Zerwes HG, Timpl R: Integrin and Arg-Gly-Asp dependence of cell adhesion to the native and unfolded triple helix of collagen type VI.

    Exp Cell Res 1993, 206:167-176. PubMed Abstract | Publisher Full Text OpenURL

  12. Specks U, Mayer U, Nischt R, Spissinger T, Mann K, Timpl R, Engel J, Chu ML: Structure of recombinant N-terminal globule of type VI collagen alpha 3 chain and its binding to heparin and hyaluronan.

    Embo J 1992, 11:4281-4290. PubMed Abstract | PubMed Central Full Text OpenURL

  13. Takahashi T, Cho HI, Kublin CL, Cintron C: Keratan sulfate and dermatan sulfate proteoglycans associate with type VI collagen in fetal rabbit cornea.

    J Histochem Cytochem 1993, 41:1447-1457. PubMed Abstract | Publisher Full Text OpenURL

  14. Tillet E, Ruggiero F, Nishiyama A, Stallcup WB: The membrane-spanning proteoglycan NG2 binds to collagens V and VI through the central nonglobular domain of its core protein.

    J Biol Chem 1997, 272:10769-10776. PubMed Abstract | Publisher Full Text OpenURL

  15. Wiberg C, Klatt AR, Wagener R, Paulsson M, Bateman JF, Heinegard D, Morgelin M: Complexes of matrilin-1 and biglycan or decorin connect collagen VI microfibrils to both collagen II and aggrecan.

    J Biol Chem 2003, 278:37698-37704. PubMed Abstract | Publisher Full Text OpenURL

  16. Chu ML, Pan TC, Conway D, Kuo HJ, Glanville RW, Timpl R, Mann K, Deutzmann R: Sequence analysis of alpha 1(VI) and alpha 2(VI) chains of human type VI collagen reveals internal triplication of globular domains similar to the A domains of von Willebrand factor and two alpha 2(VI) chain variants that differ in the carboxy terminus.

    EMBO J 1989, 8:1939-1946. PubMed Abstract | PubMed Central Full Text OpenURL

  17. Chu ML, Zhang RZ, Pan TC, Stokes D, Conway D, Kuo HJ, Glanville R, Mayer U, Mann K, Deutzmann R, Timpl R: Mosaic structure of globular domains in the human type VI collagen alpha 3 chain: similarity to von Willebrand factor, fibronectin, actin, salivary proteins and aprotinin type protease inhibitors.

    EMBO J 1990, 9:385-393. PubMed Abstract | PubMed Central Full Text OpenURL

  18. Weil D, Mattei MG, Passage E, N'Guyen VC, Pribula-Conway D, Mann K, Deutzmann R, Timpl R, Chu ML: Cloning and chromosomal localization of human genes encoding the three chains of type VI collagen.

    Am J Hum Genet 1988, 42:435-445. PubMed Abstract | PubMed Central Full Text OpenURL

  19. Fitzgerald J, Rich C, Zhou FH, Hansen U: Three novel collagen VI Chains, {alpha}4(VI), {alpha}5(VI), and {alpha}6(VI).

    J Biol Chem 2008, 283:20170-20180. PubMed Abstract | Publisher Full Text OpenURL

  20. Gara SK, Grumati P, Urciuolo A, Bonaldo P, Kobbe B, Koch M, Paulsson M, Wagener R: Three novel collagen vi chains with high homology to the {alpha}3 chain.

    J Biol Chem 2008, 283:10658-10670. PubMed Abstract | Publisher Full Text OpenURL

  21. Wagener R, Gara SK, Kobbe B, Paulsson M, Zaucke F: The knee osteoarthritis susceptibility locus DVWA on chromosome 3p24.3 is the 5' part of the split COL6A4 gene.

    Matrix Biol 2009, 28:307-310. PubMed Abstract | Publisher Full Text OpenURL

  22. Sabatelli P, Gara SK, Grumati P, Urciuolo A, Gualandi F, Curci R, Squarzoni S, Zamparelli A, Martoni E, Merlini L, Paulsson M, Bonaldo P, Wagener R: Expression of the collagen VI [alpha]5 and [alpha]6 chains in normal human skin and in skin of patients with collagen VI-related myopathies.

    J Invest Dermatol 2010, 131:99-107. PubMed Abstract | Publisher Full Text OpenURL

  23. Söderhäll C, Marenholz I, Kerscher T, Rüschendorf F, Esparza-Gordillo J, Worm M, Gruber C, Mayr G, Albrecht M, Rohde K, Schulz H, Wahn U, Hubner N, Lee YA: Variants in a novel epidermal collagen gene (col29a1) are associated with atopic dermatitis.

    PLoS Biology 2007, 5:e242. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  24. Castro-Giner F, Bustamante M, Ramon Gonzalez J, Kogevinas M, Jarvis D, Heinrich J, Anto J-M, Wjst M, Estivill X, de Cid R: A pooling-based genome-wide analysis identifies new potential candidate genes for atopy in the European Community Respiratory Health Survey (ECRHS).

    BMC Medical Genetics 2009, 10:128. PubMed Abstract | BioMed Central Full Text | PubMed Central Full Text OpenURL

  25. Esparza-Gordillo J, Weidinger S, Folster-Holst R, Bauerfeind A, Ruschendorf F, Patone G, Rohde K, Marenholz I, Schulz F, Kerscher T, Hubner U, Wahn S, Schreiber A, Franke R, Vogler S, Heath H, Baurecht N, Novak E, Rodriguez T, Illig M-A, Lee-Kirsch A, Ciechanowicz M, Kurek T, Piskackova M, Macek Y-A, Lee Ruether A: A common variant on chromosome 11q13 is associated with atopic dermatitis.

    Nat Genet 2009, 41:596-601. PubMed Abstract | Publisher Full Text OpenURL

  26. Braghetta P, Fabbro C, Piccolo S, Marvulli D, Bonaldo P, Volpin D, Bressan GM: Distinct regions control transcriptional activation of the alpha1(VI) collagen promoter in different tissues of transgenic mice.

    J Cell Biol 1996, 135:1163-1177. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  27. Braghetta P, Ferrari A, Fabbro C, Bizzotto D, Volpin D, Bonaldo P, Bressan GM: An enhancer required for transcription of the Col6a1 gene in muscle connective tissue is induced by signals released from muscle cells.

    Exp Cell Res 2008, 314:3508-3518. PubMed Abstract | Publisher Full Text OpenURL

  28. Girotto D, Fabbro C, Braghetta P, Vitale P, Volpin D, Bressan GM: Analysis of transcription of the Col6a1 gene in a specific set of tissues suggests a new variant of enhancer region.

    J Biol Chem 2000, 275:17381-17390. PubMed Abstract | Publisher Full Text OpenURL

  29. Baldock C, Sherratt MJ, Shuttleworth CA, Kielty CM: The supramolecular organization of collagen VI microfibrils.

    J Mol Biol 2003, 330:297-307. PubMed Abstract | Publisher Full Text OpenURL

  30. Ball S, Bella J, Kielty C, Shuttleworth A: Structural basis of type VI collagen dimer formation.

    J Biol Chem 2003, 278:15326-15332. PubMed Abstract | Publisher Full Text OpenURL

  31. Chu M, Conway D, Pan T, Baldwin C, Mann K, Deutzmann R, Timpl R: Amino acid sequence of the triple-helical domain of human collagen type VI.

    J Biol Chem 1988, 263:18601-18606. PubMed Abstract | Publisher Full Text OpenURL

  32. Engel J, Furthmayr H, Odermatt E, Von Der Mark H, Aumailley M, Fleischmajer R, Timpl R: Structure and macromolecular organization of type VI collagen.

    Annals of the New York Academy of Sciences 1985, 460:25-37. PubMed Abstract | Publisher Full Text OpenURL

  33. Engvall E, Hessle H, Klier G: Molecular assembly, secretion, and matrix deposition of type VI collagen.

    J Cell Biol 1986, 102:703-710. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  34. Furthmayr H, Wiedemann H, Timpl R, Odermatt E, Engel J: Electron-microscopical approach to a structural model of intima collagen.

    Biochem J 1983, 211:303-311. PubMed Abstract | PubMed Central Full Text OpenURL

  35. Myllyharju J, Kivirikko KI: Collagens, modifying enzymes and their mutations in humans, flies and worms.

    Trends in Genet 2004, 20:33-43. Publisher Full Text OpenURL

  36. Risteli M, Ruotsalainen H, Salo AM, Sormunen R, Sipilä L, Baker NL, Lamande SR, Vimpari-Kauppinen L, Myllylä R: Reduction of Lysyl hydroxylase 3 causes deleterious changes in the deposition and organization of extracellular Matrix.

    J Biol Chem 2009, 284:28204-28211. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  37. Sipilä L, Ruotsalainen H, Sormunen R, Baker NL, Lamande SR, Vapola M, Wang C, Sado Y, Aszodi A, Myllylä R: Secretion and assembly of type IV and VI collagens depend on glycosylation of hydroxylysines.

    J Biol Chem 2007, 282:33381-33388. PubMed Abstract | Publisher Full Text OpenURL

  38. Allamand V, Merlini L, Bushby K: 166th ENMC International Workshop on Collagen type VI-related Myopathies, 22-24 May 2009, Naarden, The Netherlands.

    Neuromusc Disord 2010, 20:346-354. PubMed Abstract | Publisher Full Text OpenURL

  39. Lampe AK, Bushby KMD: Collagen VI related muscle disorders.

    J Med Genet 2005, 42:673-685. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  40. Nonaka I, Une Y, Ishihara T, Miyoshino S, Nakashima T, Sugita H: A clinical and histological study of Ullrich's disease (congenital atonic-sclerotic muscular dystrophy).

    Neuroped 1981, 12:197-208. Publisher Full Text OpenURL

  41. Ullrich O: Kongenitale, atonisch-sklerotische Muskeldystrophie, ein weiteres Typus der heredodegenerativen Erkrankungen des neuromuskulären Systems.

    Z Gesamte Neurol Psychiat 1930, 126:171-201. Publisher Full Text OpenURL

  42. Briñas L, Richard P, Quijano-Roy S, Gartioux C, Ledeuil C, Makri S, Ferreiro A, Maugenre S, Topaloglu H, Haliloglu G, Pénisson-Besnier I, Jeannet P-Y, Merlini L, Navarro C, Toutain A, Chaigne D, Desguerre I, de Die-Smulders C, Dunand M, Echenne B, Eymard B, Kuntzer T, Maincent K, Mayer M, Plessis G, Rivier F, Roelens F, Stojkovic T, Taratuto A, Lubieniecki F, et al.: Early onset collagen VI myopathies: genetic and clinical correlations.

    Annals of Neurol 2010, 68:511-520. Publisher Full Text OpenURL

  43. Nadeau A, Kinali M, Main M, Jimenez-Mallebrera C, Aloysius A, Clement E, North B, Manzur AY, Robb SA, Mercuri E, Muntoni F: Natural history of Ullrich congenital muscular dystrophy.

    Neurology 2009, 73:25-31. PubMed Abstract | Publisher Full Text OpenURL

  44. Bethlem J, Van Wijngaarden GK: Benign myopathy with autosomal dominant inheritance: a report of three pedigrees.

    Brain 1976, 99:91-100. PubMed Abstract | Publisher Full Text OpenURL

  45. De Visser M, van der Kooi AJ, Jobsis GJ: Bethlem myopathy. In Myology. Edited by Franzini-Amstrong AGEaC. New York: McGraw-Hill; 2004:1135-1146. OpenURL

  46. Jobsis GJ, Boers JM, Barth PG, de Visser M: Bethlem myopathy: a slowly progressive congenital muscular dystrophy with contractures.

    Brain 1999, 122:649-655. PubMed Abstract | Publisher Full Text OpenURL

  47. Kirschner J, Hausser I, Zou Y, Schreiber G, Christen HJ, Brown SC, Anton-Lamprecht I, Muntoni F, Hanefeld F, Bonnemann CG: Ullrich congenital muscular dystrophy: connective tissue abnormalities in the skin support overlap with Ehlers-Danlos syndromes.

    Am J Med Genet A 2005, 132:296-301. OpenURL

  48. Nalini A, Gayathri N: Bethlem myopathy: A study of two families.

    Neurol India 2010, 58:665-666. PubMed Abstract | Publisher Full Text OpenURL

  49. Pepe G, Bertini E, Bonaldo P, Bushby K, Giusti B, de Visser M, Guicheney P, Lattanzi G, Merlini L, Muntoni F, Nishino I, Nonaka I, Ben Yaou R, Sabatelli P, Sewry C, Topaloglu H, van der Kooi A: Bethlem myopathy (BETHLEM) and Ullrich scleroatonic muscular dystrophy: 100th ENMC International Workshop, 23-24 November 2001, Naarden, The Netherlands.

    Neuromusc Disord 2002, 12:984-993. PubMed Abstract | Publisher Full Text OpenURL

  50. Merlini L, Martoni E, Grumati P, Sabatelli P, Squarzoni S, Urciuolo A, Ferlini A, Gualandi F, Bonaldo P: Autosomal recessive myosclerosis myopathy is a collagen VI disorder.

    Neurology 2008, 71:1245-1253. PubMed Abstract | Publisher Full Text OpenURL

  51. Scacheri PC, Gillanders EM, Subramony SH, Vedanarayanan V, Crowe CA, Thakore N, Bingler M, Hoffman EP: Novel mutations in collagen VI genes: expansion of the Bethlem myopathy phenotype.

    Neurology 2002, 58:593-602. PubMed Abstract | Publisher Full Text OpenURL

  52. Norwood FLM, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V: Prevalence of genetic muscle disease in northern England: in-depth analysis of a muscle clinic population.

    Brain 2009, 132:3175-3186. PubMed Abstract | Publisher Full Text OpenURL

  53. Okada M, Kawahara G, Noguchi S, Sugie K, Murayama K, Nonaka I, Hayashi YK, Nishino I: Primary collagen VI deficiency is the second most common congenital muscular dystrophy in Japan.

    Neurology 2007, 69:1035-1042. PubMed Abstract | Publisher Full Text OpenURL

  54. Peat RA, Smith JM, Compton AG, Baker NL, Pace RA, Burkin DJ, Kaufman SJ, Lamande SR, North KN: Diagnosis and etiology of congenital muscular dystrophy.

    Neurology 2008, 71:312-321. PubMed Abstract | Publisher Full Text OpenURL

  55. Bateman JF, Boot-Handford RP, Lamande SR: Genetic diseases of connective tissues: cellular and extracellular effects of ECM mutations.

    Nat Rev Genet 2009, 10:173-183. PubMed Abstract | Publisher Full Text OpenURL

  56. Voermans NC, Bönnemann CG, Huijing PA, Hamel BC, van Kuppevelt TH, de Haan A, Schalkwijk J, van Engelen BG, Jenniskens GJ: Clinical and molecular overlap between myopathies and inherited connective tissue diseases.

    Neuromusc Disord 2008, 18:843-856. PubMed Abstract | Publisher Full Text OpenURL

  57. Voermans NC, van Alfen N, Pillen S, Lammens M, Schalkwijk J, Zwarts MJ, van Rooij IA, Hamel BC, van Engelen BG: Neuromuscular involvement in various types of Ehlers-Danlos syndrome.

    Annals of Neurol 2009, 65:687-697. Publisher Full Text OpenURL

  58. Deconinck N, Dion E, Ben Yaou R, Ferreiro A, Eymard B, Briñas L, Payan C, Voit T, Guicheney P, Richard P, Allamand V, Bonne G, Stojkovic T: Differentiating Emery-Dreifuss muscular dystrophy and collagen VI-related myopathies using a specific CT scanner pattern.

    Neuromusc Disord 2010, 20:517-523. PubMed Abstract | Publisher Full Text OpenURL

  59. Mercuri E, Clements E, Offiah A, Pichiecchio A, Vasco G, Bianco F, Berardinelli A, Manzur A, Pane M, Messina S, Gualandi F, Ricci E, Rutherford M, Muntoni F: Muscle magnetic resonance imaging involvement in muscular dystrophies with rigidity of the spine.

    Annals of Neurol 2010, 67:201-208. Publisher Full Text OpenURL

  60. Mercuri E, Cini C, Pichiecchio A, Allsop J, Counsell S, Zolkipli Z, Messina S, Kinali M, Brown SC, Jimenez C: Muscle magnetic resonance imaging in patients with congenital muscular dystrophy and Ullrich phenotype.

    Neuromusc Disord 2003, 13:554-558. PubMed Abstract | Publisher Full Text OpenURL

  61. Mercuri E, Lampe A, Allsop J, Knight R, Pane M, Kinali M, Bonnemann C, Flanigan K, Lapini I, Bushby K, Pepe G, Muntoni F: Muscle MRI in Ullrich congenital muscular dystrophy and Bethlem myopathy.

    Neuromusc Disord 2005, 15:303-310. PubMed Abstract | Publisher Full Text OpenURL

  62. Bönnemann C, Brockmann K, Hanefeld F: Muscle ultrasound in Bethlem myopathy.

    Neuroped 2003, 34:335-336. OpenURL

  63. Kawahara G, Okada M, Morone N, Ibarra CA, Nonaka I, Noguchi S, Hayashi YK, Nishino I: Reduced cell anchorage may cause sarcolemma-specific collagen VI deficiency in Ullrich disease.

    Neurology 2007, 69:1043-1049. PubMed Abstract | Publisher Full Text OpenURL

  64. Hicks D, Lampe AK, Barresi R, Charlton R, Fiorillo C, Bonnemann CG, Hudson J, Sutton R, Lochmuller H, Straub V, Bushby K: A refined diagnostic algorithm for Bethlem myopathy.

    Neurology 2008, 70:1192-1199. PubMed Abstract | Publisher Full Text OpenURL

  65. Camacho Vanegas O, Bertini E, Zhang R-Z, Petrini S, Minosse C, Sabatelli P, Giusti B, Chu M-F, Pepe G: Ullrich scleroatonic muscular dystrophy is caused by recessive mutations in collagen type VI.

    Proc Natl Acad Sci USA 2001, 98:7516-7521. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  66. Demir E, Ferreiro A, Sabatelli P, Allamand V, Makri S, Echenne B, Maraldi NM, Merlini L, Topaloglu H, Guicheney P: Collagen VI status and clinical severity in Ullrich congenital muscular dystrophy: phenotype analysis of 11 families linked to the COL6 loci.

    Neuroped 2004, 35:103-112. OpenURL

  67. Demir E, Sabatelli P, Allamand V, Ferreiro A, Moghadaszadeh B, Makrelouf M, Topaloglu H, Echenne B, Merlini L, Guicheney P: Mutations in COL6A3 cause severe and mild phenotypes of Ullrich congenital muscular dystrophy.

    Am J Hum Genet 2002, 70:1446-1458. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  68. Baker NL, Morgelin M, Peat R, Goemans N, North KN, Bateman JF, Lamande SR: Dominant collagen VI mutations are a common cause of Ullrich congenital muscular dystrophy.

    Hum Mol Genet 2005, 14:279-293. PubMed Abstract | Publisher Full Text OpenURL

  69. Jobsis GJ, Keizers H, Vreijling JP, de Visser M, Speer MC, Wolterman RA, Baas F, Bolhuis PA: Type VI collagen mutations in Bethlem myopathy, an autosomal dominant myopathy with contractures.

    Nat Genet 1996, 14:113-115. PubMed Abstract | Publisher Full Text OpenURL

  70. Foley AR, Hu Y, Zou Y, Columbus A, Shoffner J, Dunn DM, Weiss RB, Bonnemann CG: Autosomal recessive inheritance of classic Bethlem myopathy.

    Neuromusc Disord 2009, 19:813-817. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  71. Gualandi F, Urciuolo A, Martoni E, Sabatelli P, Squarzoni S, Bovolenta M, Messina S, Mercuri E, Franchella A, Ferlini A, Bonaldo P, Merlini L: Autosomal recessive Bethlem myopathy.

    Neurology 2009, 73:1883-1891. PubMed Abstract | Publisher Full Text OpenURL

  72. Pepe G, Bertini E, Giusti B, Brunelli T, Comeglio P, Saitta B, Merlini L, Chu ML, Federici G, Abbate R: A novel de novo mutation in the triple helix of the COL6A3 gene in a two-generation Italian family affected by Bethlem myopathy. A diagnostic approach in the mutations' screening of type VI collagen.

    Neuromusc Disord 1999, 9:264-271. PubMed Abstract | Publisher Full Text OpenURL

  73. Pepe G, de Visser M, Bertini E, Bushby K, Vanegas OC, Chu ML, Lattanzi G, Merlini L, Muntoni F, Urtizberea A: Bethlem myopathy (BETHLEM) 86th ENMC international workshop, 10-11 November 2000, Naarden, The Netherlands.

    Neuromusc Disord 2002, 12:296-305. PubMed Abstract | Publisher Full Text OpenURL

  74. Lamandé SR, Morgelin M, Selan C, Jobsis GJ, Baas F, Bateman JF: Kinked collagen VI tetramers and reduced microfibril formation as a result of Bethlem myopathy and introduced triple helical glycine mutations.

    J Biol Chem 2002, 277:1949-1956. PubMed Abstract | Publisher Full Text OpenURL

  75. Lamandé SR, Shields KA, Kornberg AJ, Shield LK, Bateman JF: Bethlem myopathy and engineered collagen VI triple helical deletions prevent intracellular multimer assembly and protein secretion.

    J Biol Chem 1999, 274:21817-21822. PubMed Abstract | Publisher Full Text OpenURL

  76. Pace R, Peat R, Baker N, Zamurs L, Mörgelin M, Irving M, Adams N, Bateman J, Mowat D, Smith N, Lamont P, Moore S, Mathews K, North K, Lamandé S: Collagen VI glycine mutations: perturbed assembly and a spectrum of clinical severity.

    Annals of Neurol 2008, 64:294-303. Publisher Full Text OpenURL

  77. Sasaki T, Hohenester E, Zhang RZ, Gotta S, Speer MC, Tandan R, Timpl R, Chu ML: A Bethlem myopathy Gly to Glu mutation in the von Willebrand factor A domain N2 of the collagen alpha3(VI) chain interferes with protein folding.

    Faseb J 2000, 14:761-768. PubMed Abstract | Publisher Full Text OpenURL

  78. Baker NL, Mörgelin M, Pace RA, Peat RA, Adams NE, Gardner RJM, Rowland LP, Miller G, De Jonghe P, Ceulemans B, Hannibal MC, Edwards M, Thompson EM, Jacobson R, Quinlivan RCM, Aftimos S, Kornberg AJ, North KN, Bateman JF, Lamandé SR: Molecular consequences of dominant Bethlem myopathy collagen VI mutations.

    Annals of Neurol 2007, 9999:NA. OpenURL

  79. Lampe AK, Dunn DM, von Niederhausern AC, Hamil C, Aoyagi A, Laval SH, Marie SK, Chu M-L, Swoboda K, Muntoni F, Bönnemann CG, Flanigan KM, Bushby KMD, Weiss RB: Automated genomic sequence analysis of the three collagen VI genes: applications to Ullrich congenital muscular dystrophy and Bethlem myopathy.

    J Med Genet 2005, 42:108-120. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  80. Lampe AK, Zou Y, Sudano D, O'Brien KK, Hicks D, Laval SH, Charlton R, Jimenez-Mallebrera C, Zhang RZ, Finkel RS, Tennekoon G, Schreiber G, van der Knaap MS, Marks H, Straub V, Flanigan KM, Chu ML, Muntoni F, Bushby KMD, Bönnemann CG: Exon skipping mutations in collagen VI are common and are predictive for severity and inheritance.

    Human Mut 2008, 29:809-822. Publisher Full Text OpenURL

  81. Lucioli S, Giusti B, Mercuri E, Camacho Vanegas O, Lucarini L, Pietroni V, Urtizberea J-A, Ben Yaou R, de Visser M, van der Kooi AJ, Bönnemann CG, Iannaccone ST, Merlini L, Bushby K, Muntoni F, Bertini E, Chu ML, Pepe G: Detection of common and private mutations in the COL6A1 gene of patients with Bethlem myopathy.

    Neurology 2005, 64:1931-1937. PubMed Abstract | Publisher Full Text OpenURL

  82. Pan T, Zhang R, Sudano D, Marie S, Bönnemann C, Chu M: New molecular mechanism for Ullrich congenital muscular dystrophy: a heterozygous in-frame deletion in the COL6A1 gene causes a severe phenotype.

    Am J Hum Genet 2003, 73:355-369. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  83. Pepe G, Giusti B, Bertini E, Brunelli T, Saitta B, Comeglio P, Bolognese A, Merlini L, Federici G, Abbate R, Chu M-L: A Heterozygous splice site mutation in COL6A1 leading to an in-frame deletion of the [alpha]1(VI) collagen chain in an Italian family affected by Bethlem myopathy.

    Biochem Biophys Res Com 1999, 258:802-807. PubMed Abstract | Publisher Full Text OpenURL

  84. Giusti B, Lucarini L, Pietroni V, Lucioli S, Bandinelli B, Petrini S, Gartioux C, Talim B, Roelens F, Merlini L, Topaloglu H, Bertini E, Guicheney P, Pepe G: Dominant and recessive COL6A1 mutations in Ullrich scleroatonic muscular dystrophy.

    Ann Neurol 2005, 58:400-410. PubMed Abstract | Publisher Full Text OpenURL

  85. Jimenez-Mallebrera C, Maioli MA, Kim J, Brown SC, Feng L, Lampe AK, Bushby K, Hicks D, Flanigan KM, Bonnemann C, Sewry CA, Muntoni F: A comparative analysis of collagen VI production in muscle, skin and fibroblasts from 14 Ullrich congenital muscular dystrophy patients with dominant and recessive COL6A mutations.

    Neuromusc Disorders 2006, 16:571-582. PubMed Abstract | Publisher Full Text OpenURL

  86. Lamandé SR, Sigalas E, Pan TC, Chu ML, Dziadek M, Timpl R, Bateman JF: The role of the alpha3(VI) chain in collagen VI assembly. Expression of an alpha3(VI) chain lacking N-terminal modules N10-N7 restores collagen VI assembly, secretion, and matrix deposition in an alpha3(VI)- deficient cell line.

    J Biol Chem 1998, 273:7423-7430. PubMed Abstract | Publisher Full Text OpenURL

  87. Lucarini L, Giusti B, Zhang R-Z, Pan TC, Jimenez-Mallebrera C, Mercuri E, Muntoni F, Pepe G, Chu M-L: A homozygous COL6A2 intron mutation causes in-frame triple-helical deletion and nonsense-mediated mRNA decay in a patient with Ullrich congenital muscular dystrophy.

    Hum Genet 2005, 117:460-466. PubMed Abstract | Publisher Full Text OpenURL

  88. Martoni E, Urciuolo A, Sabatelli P, Fabris M, Bovolenta M, Neri M, Grumati P, D'Amico A, Pane M, Mercuri E, Bertini E, Merlini L, Bonaldo P, Ferlini A, Gualandi F: Identification and characterization of novel collagen VI non-canonical splicing mutations causing ullrich congenital muscular dystrophy.

    Human Mut 2009, 30:E662-E672. Publisher Full Text OpenURL

  89. Peat RA, Baker NL, Jones KJ, North KN, Lamande SR: Variable penetrance of COL6A1 null mutations: Implications for prenatal diagnosis and genetic counselling in Ullrich congenital muscular dystrophy families.

    Neuromusc Disorders 2007, 17:547-557. PubMed Abstract | Publisher Full Text OpenURL

  90. Pepe G, Lucarini L, Zhang RZ, Pan T, Giusti B, Quijano-Roy S, Gartioux C, Bushby KM, Guicheney P, Chu ML: COL6A1 genomic deletions in Bethlem myopathy and Ullrich muscular dystrophy.

    Ann Neurol 2006, 59:190-195. PubMed Abstract | Publisher Full Text OpenURL

  91. Tooley LD, Zamurs LK, Beecher N, Baker NL, Peat RA, Adams NE, Bateman JF, North KN, Baldock C, Lamande SR: Collagen VI microfibril formation is abolished by an alpha(VI) von Willebrand factor A-domain mutation in a patient with Ullrich congenital muscular dystrophy.

    J Biol Chem 2010. OpenURL

  92. Zhang R-Z, Zou Y, Pan T-C, Markova D, Fertala A, Hu Y, Squarzoni S, Reed UC, Marie SKN, Bonnemann CG, Chu M-L: Recessive COL6A2 C-globular missense mutations in Ullrich congenital muscular dystrophy.

    J Biol Chem 2010, 285:10005-10015. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  93. Chang YF, Imam JS, Wilkinson MF: The nonsense-mediated decay RNA surveillance pathway.

    Annual Review of Biochemistry 2007, 76:51-74. PubMed Abstract | Publisher Full Text OpenURL

  94. Maquat LE, Carmichael GG: Quality control of mRNA function.

    Cell 2001, 104:173-176. PubMed Abstract | Publisher Full Text OpenURL

  95. Bovolenta M, Neri M, Martoni E, Urciuolo A, Sabatelli P, Fabris M, Grumati P, Mercuri E, Bertini E, Merlini L, Bonaldo P, Ferlini A, Gualandi F: 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.

    BMC Medical Genetics 2010, 11:44. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  96. Foley AR, Hu Y, Zou Y, Yang M, Medne L, Leach M, Conlin LK, Spinner N, Shaikh TH, Falk M, Neumeyer AM, Bliss L, Tseng BS, Winder TL, Bönnemann CG: Large genomic deletions: A novel cause of Ullrich congenital muscular dystrophy.

    Annals of Neurol 2011, 69:206-211. Publisher Full Text OpenURL

  97. Bonaldo P, Braghetta P, Zanetti M, Piccolo S, Volpin D, Bressan GM: Collagen VI deficiency induces early onset myopathy in the mouse: an animal model for Bethlem myopathy.

    Hum Mol Genet 1998, 7:2135-2140. PubMed Abstract | Publisher Full Text OpenURL

  98. Irwin W, Bergamin N, Sabatelli P, Reggiani C, Megighian A, Merlini L, Braghetta P, Columbaro M, Volpin D, Bressan G, Bernardi P, Bonaldo P: Mitochondrial dysfunction and apoptosis in myopathic mice with collagen VI deficiency.

    Nat Genet 2003, 35:367-371. PubMed Abstract | Publisher Full Text OpenURL

  99. Blaauw B, Agatea L, Toniolo L, Canato M, Quarta M, Dyar KA, Danieli-Betto D, Betto R, Schiaffino S, Reggiani C: Eccentric contractions lead to myofibrillar dysfunction in muscular dystrophy.

    J Applied Physiology 2010, 108:105-111. OpenURL

  100. Angelin A, Tiepolo T, Sabatelli P, Grumati P, Bergamin N, Golfieri C, Mattioli E, Gualandi F, Ferlini A, Merlini L, Maraldi NM, Bonaldo P, Bernardi P: Mitochondrial dysfunction in the pathogenesis of Ullrich congenital muscular dystrophy and prospective therapy with cyclosporins.

    Proc Natl Acad Sci USA 2007, 104:991-996. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  101. Bernardi P, Bonaldo P: Dysfunction of mitochondria and sarcoplasmic reticulum in the pathogenesis of collagen VI muscular dystrophies.

    Annals of the New York Academy of Sciences 2008, 1147:303-311. PubMed Abstract | Publisher Full Text OpenURL

  102. Hicks D, Lampe AK, Laval SH, Allamand V, Jimenez-Mallebrera C, Walter MC, Muntoni F, Quijano-Roy S, Richard P, Straub V, Lochmuller H, Bushby KMD: Cyclosporine. A treatment for Ullrich congenital muscular dystrophy: a cellular study of mitochondrial dysfunction and its rescue.

    Brain 2009, 132:147-155. PubMed Abstract | Publisher Full Text OpenURL

  103. Howell SJ, Doane KJ: Type VI collagen increases cell survival and prevents anti-[beta]1integrin-mediated apoptosis.

    Exp Cell Res 1998, 241:230-241. PubMed Abstract | Publisher Full Text OpenURL

  104. Ruhl M, Sahin E, Johannsen M, Somasundaram R, Manski D, Riecken EO, Schuppan D: Soluble collagen VI drives serum-starved fibroblasts through S Phase and prevents apoptosis via down-regulation of Bax.

    J Biol Chem 1999, 274:34361-34368. PubMed Abstract | Publisher Full Text OpenURL

  105. Grumati P, Coletto L, Sabatelli P, Cescon M, Angelin A, Bertaggia E, Blaauw B, Urciuolo A, Tiepolo T, Merlini L, Maraldi NM, Bernardi P, Sandri M, Bonaldo P: Autophagy is defective in collagen VI muscular dystrophies, and its reactivation rescues myofiber degeneration.

    Nat Med 2010, 16:1313-1320. PubMed Abstract | Publisher Full Text OpenURL

  106. Telfer WR, Busta AS, Bonnemann CG, Feldman EL, Dowling JJ: Zebrafish models of collagen VI-related myopathies.

    Hum Mol Genet 2010, 19:2433-2444. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  107. Kawahara G, Karpf JA, Myers JA, Alexander MS, Guyon JR, Kunkel LM: Drug screening in a zebrafish model of Duchenne muscular dystrophy.

    Proc Natl Acad Sci USA 2011, 108:5331-5336. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  108. Wang CH, Bonnemann CG, Rutkowski A, Sejersen T, Bellini J, Battista V, Florence JM, Schara U, Schuler PM, Wahbi K, Aloysius A, Bash RO, Béroud C, Bertini E, Bushby K, Cohn RD, Connolly AM, Deconinck N, Desguerre I, Eagle M, Estournet-Mathiaud B, Ferreiro A, Fujak A, Goemans N, Iannaccone ST, Jouinot P, Main M, Melacini P, Mueller-Felber W, Muntoni F, et al.: Consensus statement on standard of care for congenital muscular dystrophies.

    J Child Neurol 2010, 25:1559-1581. PubMed Abstract | Publisher Full Text OpenURL

  109. Merlini L, Angelin A, Tiepolo T, Braghetta P, Sabatelli P, Zamparelli A, Ferlini A, Maraldi NM, Bonaldo P, Bernardi P: Cyclosporin A corrects mitochondrial dysfunction and muscle apoptosis in patients with collagen VI myopathies.

    Proc Natl Acad Sci USA 2008, 105:5225-5229. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  110. Maraldi NM, Sabatelli P, Columbaro M, Zamparelli A, Manzoli FA, Bernardi P, Bonaldo P, Merlini L: Collagen VI myopathies: From the animal model to the clinical trial.

    Advances in Enzyme Regulation 2009, 49:197-211. PubMed Abstract | Publisher Full Text OpenURL

  111. Merlini L, Bernardi P: Therapy of collagen VI-related myopathies (Bethlem and Ullrich).

    Neurotherapeutics 2008, 5:613-618. PubMed Abstract | Publisher Full Text OpenURL

  112. Hansson MJ, Mattiasson G, Månsson R, Karlsson J, Keep MF, Waldmeier P, Ruegg UT, Dumont J-M, Besseghir K, Elmér E: The Nonimmunosuppressive cyclosporin analogs NIM811 and UNIL025 display nanomolar potencies on permeability transition in brain-derived mitochondria.

    Journal of Bioenergetics and Biomembranes 2004, 36:407-413. PubMed Abstract | Publisher Full Text OpenURL

  113. Tiepolo T, Angelin A, Palma E, Sabatelli P, Merlini L, Nicolosi L, Finetti F, Braghetta P, Vuagniaux G, Dumont JM, Baldari CT, Bonaldo P, Bernardi P: The cyclophilin inhibitor Debio 025 normalizes mitochondrial function, muscle apoptosis and ultrastructural defects in Col6a1-/- myopathic mice.

    British Journal of Pharmacology 2009, 157:1045-1052. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  114. Erb M, Meinen S, Barzaghi P, Sumanovski LT, Courdier-Fruh I, Ruegg MA, Meier T: Omigapil ameliorates the pathology of muscle dystrophy caused by laminin-{alpha}2 deficiency.

    J Pharmacol Exp Ther 2009, 331:787-795. PubMed Abstract | Publisher Full Text OpenURL

  115. Zingman LV, Park S, Olson TM, Alekseev AE, Terzic A: Aminoglycoside-induced translational read-through in disease: overcoming nonsense mutations by pharmacogenetic therapy.

    Clin Pharmacol Ther 2007, 81:99-103. PubMed Abstract | Publisher Full Text OpenURL