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Collagen VI-related dystrophies (COL6-RD) display a wide spectrum of disease severity and genetic variability ranging from mild Bethlem myopathy (BM) to severe Ullrich congenital muscular dystrophy (UCMD) and the intermediate severities in between with dual modes of inheritance, dominant and recessive. In the current study, next-generation sequencing demonstrated potential variants in the genes coding for the three alpha chains of collagen VI (COL6A1, COL6A2, or COL6A3) in a cohort of Egyptian patients with progressive muscle weakness (n = 23). Based on the age of disease onset and the patient clinical course, subjects were diagnosed as follows: 12 with UCMD, 8 with BM, and 3 with intermediate disease form. Fourteen pathogenic variants, including 5 novel alterations, were reported in the enrolled subjects. They included 3 missense, 3 frameshift, and 6 splicing variants in 4, 3, and 6 families, respectively. In addition, a nonsense variant in a single family and an inframe variant in 3 different families were also detected. Recessive and dominant modes of inheritance were recorded in 9 and 8 families, respectively. According to ACMG guidelines, variants were classified as pathogenic (n = 7), likely pathogenic (n = 4), or VUS (n = 3) with significant pathogenic potential. To our knowledge, the study provided the first report of the clinical and genetic findings of a cohort of Egyptian patients with collagen VI deficiency. Inter- and intra-familial clinical variability was evident among the study cohort. [ABSTRACT FROM AUTHOR]

Introduction: Bethlem myopathy is a rare genetic disease caused by a variant mapped to 21q22, which harbors the collagen type VI alpha 2 chain (COL6A2) and collagen type VI alpha 1 chain (COL6A1) genes, and 2q37, which harbors the collagen type VI alpha 3 chain (COL6A3) gene. Disease onset can occur at any age, and the symptoms are related to those of muscular dystrophy. Since Bethlem myopathy is a rare disease, no previous studies have been conducted in Arab countries, including Saudi Arabia. Its variable presentation of nonspecific muscular contractions and severity represents a diagnostic dilemma. Case presentation: Here, we report a Saudi pediatric patient, who is 9 years old (proband), brought to the pediatric clinic of King Saud's Hospital by his mother. The boy presented with difficulty standing, walking, and running with his classmates and unaffected siblings. He has a younger sibling, aged 6 years old, who reported having a limping gait and difficulty bending his right knee. Laboratory results for the proband were unremarkable except for a slight increase in creatine kinase (CK). Whole-exome sequencing (WES) was performed for five family members, including the proband and his symptomatic brother, their mother and two asymptomatic siblings. A very rare 3′ splice site acceptor intronic variant, NM_001849.4: c.1817-3C>G, located three nucleotides before exon 25, was identified in COL6A2. Bioinformatics tools (SpliceAI, dbscSNV, FATHMM-MKL, and MaxEntScan) predicted this variant as pathogenic. The proband and his 6-year-old sibling presented a homozygous genotype for the variant, whereas the mother and one asymptomatic sibling were heterozygous, and the other sibling carried homozygous wild-type alleles. Conclusions: This is the first study to report a case of Bethlem myopathy confirmed by WES in Saudi Arabia and all Arab nations. The identified variant is rare, and its segregation pattern suggests autosomal recessive inheritance. The segregation pattern and bioinformatics tool results may qualify this variant to be annotated as pathogenic, addressing the reported uncertainty of its classification. Our findings contribute to linking and filling the knowledge gap of diagnosing and managing patients with collagen VI-related myopathies, providing greater clinical and genetic understanding to the existing knowledge. [ABSTRACT FROM AUTHOR]

Background: Collagen VI‐related disorder (COLVI‐RD) is one of the most common congenital muscular dystrophies. However, data is limited in China. Methods: We conducted a retrospective study at two tertiary centers. Clinical presentations, lab findings (including serum creatine kinase levels), muscle biopsy, and molecular test results for patients diagnosed with definite COLVI‐RD were collected. Results: A total of 82 patients were enrolled in the study, including 4 with early–severe Ullrich congenital muscular dystrophy (E–S UCMD) (4.8%), 45 with moderate–progressive Ullrich congenital muscular dystrophy (M–P UCMD, 54.9%), 19 with mild UCMD (23.2%), and 14 with Bethlem myopathy (BM, 17.1%). Feeding difficulty, DDH, and neurogenic damage were more common in E–S and M–P UCMD, while contracture of distal joints, atrophic scars, and hyperkeratosis was more prominent in mild UCMD and BM. Seventy patients harbored 64 pathogenic mutations in COLVI‐related genes: 28 patients in COL6A1 gene, 25 patients in the COL6A2 gene, and 17 patients in the COL6A3 gene, among which 33 mutations were novel. Missense and splicing mutations were predominant for COL6A1 and COL6A3 genes, which were mostly located in N‐terminus of THD, in a dominant pattern, while mutations in the COL6A2 gene were much more polymorphic, which spread throughout the whole length of the gene, in a dominant or recessive pattern. Immunofluorescence dual labeling of Collagen VI/IV in 44 patients showed complete deficiency of Collagen VI in 10 patients (22.7%), sarcolemma‐specific Collagen VI deficiency in 25 patients (56.8%), and normal Collagen VI staining in 9 patients (20.5%). Conclusion: Our study reported the largest cohort of COLVI‐RD in China, which showed M–P UCMD was the most common phenotype, followed by mild UCMD and BM. We identified 30 novel mutations and expanded the genetic spectrum. Missense and splicing mutations were predominant for COL6A1 and COL6A3 genes, while mutations in the COL6A2 gene were much more polymorphic. For severe phenotypes, most mutations are sporadic, while some are AD or recessive inherited. For milder phenotypes, sporadic and AD inherited were both common, while only 1 patient with recessive mutations was observed. [ABSTRACT FROM AUTHOR]

Key Clinical Message: This case highlights the challenges in diagnosing Bethlem myopathy, the need for a high index of suspicion, and the importance of recognizing the diverse clinical presentations of this rare condition. Enhanced understanding can aid in early diagnosis and tailored management. Bethlem myopathy (BM), a rare collagen VI‐related myopathy, is characterized by progressive muscle weakness and contractures, typically affecting the proximal muscles and joints. This case report presents a 15‐year‐old girl from Tehran, Iran, with a 5‐year history of severe limb pain and progressive weakness. Born to consanguineous parents, the patient displayed delayed walking milestones and significant hypotonia, leading to a waddling gait and lumbar hyperlordosis. Neurological examination revealed marked proximal lower limb weakness, a positive Gowers' sign, and absent myotatic reflexes. Elevated creatine phosphokinase (CPK) levels and electromyography (EMG) results indicated myopathy, while nerve conduction studies showed no neuropathy. Genetic testing revealed a novel homozygous variant of c.385C>T (p.Arg129Cys) in the COL6A2 gene, classified as a variant of uncertain significance (VUS) per American College of Medical Genetics and Genomics (ACMG) guidelines due to its rarity and specific phenotype association. Differential diagnosis is essential to distinguish it from other neuromuscular conditions. Management primarily focuses on symptom relief and enhancing patients' quality of life. This case highlights the challenges in diagnosing BM, the need for a high index of suspicion, and the importance of recognizing the diverse clinical presentations of this rare condition. Enhanced understanding can aid in early diagnosis and tailored management. [ABSTRACT FROM AUTHOR]

Abstract Background Bethlem Myopathy is a collagen VI-related myopathy presenting as a rare hereditary muscular disorder with progressive muscular weakness and joint contractures. Despite its milder clinical course relative to other myopathies, anaesthetic management can be challenging. High arched palates and fixed flexion deformities may contribute to a difficult airway. A progressive decline in pulmonary function can present later into adulthood. This respiratory decline can carry secondary cardiovascular consequences due to the progressive nature of restrictive lung disease, including right sided heart disease and pulmonary hypertension. We describe a case of a male patient with Bethlem Myopathy undergoing anaesthesia, to contribute to the limited body of literature on this condition and enhance awareness and guidance amongst anaesthesiologists on approaching patients with this condition. This is the first case report within the literature of its kind. Case presentation This case details a 33-year-old male with Bethlem Myopathy undergoing tonsillectomy. Diagnosed in childhood following developmental delays, the patient had no prior anaesthetic exposure and no family history of anaesthetic complications. Anaesthetic induction was achieved without complications, avoiding depolarizing muscle relaxants and careful airway management. Extreme care was taken in patient positioning to prevent complications. The surgery proceeded without incident and muscle paralysis was reversed with Suggammadex, resulting in no adverse post-operative respiratory complications. The patient was discharged on the first post-operative day without any respiratory or cardiovascular compromise. Conclusions Bethlem Myopathy, while often exhibiting a mild clinical course, can present anaesthetic challenges. Awareness of potential complications including a difficult airway, cardiovascular and respiratory implications as well as the need for specialised monitoring and positioning is crucial to ensure a safe peri-operative course.

Background: Bethlem Myopathy is a collagen VI-related myopathy presenting as a rare hereditary muscular disorder with progressive muscular weakness and joint contractures. Despite its milder clinical course relative to other myopathies, anaesthetic management can be challenging. High arched palates and fixed flexion deformities may contribute to a difficult airway. A progressive decline in pulmonary function can present later into adulthood. This respiratory decline can carry secondary cardiovascular consequences due to the progressive nature of restrictive lung disease, including right sided heart disease and pulmonary hypertension. We describe a case of a male patient with Bethlem Myopathy undergoing anaesthesia, to contribute to the limited body of literature on this condition and enhance awareness and guidance amongst anaesthesiologists on approaching patients with this condition. This is the first case report within the literature of its kind. Case presentation: This case details a 33-year-old male with Bethlem Myopathy undergoing tonsillectomy. Diagnosed in childhood following developmental delays, the patient had no prior anaesthetic exposure and no family history of anaesthetic complications. Anaesthetic induction was achieved without complications, avoiding depolarizing muscle relaxants and careful airway management. Extreme care was taken in patient positioning to prevent complications. The surgery proceeded without incident and muscle paralysis was reversed with Suggammadex, resulting in no adverse post-operative respiratory complications. The patient was discharged on the first post-operative day without any respiratory or cardiovascular compromise. Conclusions: Bethlem Myopathy, while often exhibiting a mild clinical course, can present anaesthetic challenges. Awareness of potential complications including a difficult airway, cardiovascular and respiratory implications as well as the need for specialised monitoring and positioning is crucial to ensure a safe peri-operative course. [ABSTRACT FROM AUTHOR]

Key Clinical Message This case highlights the challenges in diagnosing Bethlem myopathy, the need for a high index of suspicion, and the importance of recognizing the diverse clinical presentations of this rare condition. Enhanced understanding can aid in early diagnosis and tailored management. Abstract Bethlem myopathy (BM), a rare collagen VI‐related myopathy, is characterized by progressive muscle weakness and contractures, typically affecting the proximal muscles and joints. This case report presents a 15‐year‐old girl from Tehran, Iran, with a 5‐year history of severe limb pain and progressive weakness. Born to consanguineous parents, the patient displayed delayed walking milestones and significant hypotonia, leading to a waddling gait and lumbar hyperlordosis. Neurological examination revealed marked proximal lower limb weakness, a positive Gowers' sign, and absent myotatic reflexes. Elevated creatine phosphokinase (CPK) levels and electromyography (EMG) results indicated myopathy, while nerve conduction studies showed no neuropathy. Genetic testing revealed a novel homozygous variant of c.385C>T (p.Arg129Cys) in the COL6A2 gene, classified as a variant of uncertain significance (VUS) per American College of Medical Genetics and Genomics (ACMG) guidelines due to its rarity and specific phenotype association. Differential diagnosis is essential to distinguish it from other neuromuscular conditions. Management primarily focuses on symptom relief and enhancing patients' quality of life. This case highlights the challenges in diagnosing BM, the need for a high index of suspicion, and the importance of recognizing the diverse clinical presentations of this rare condition. Enhanced understanding can aid in early diagnosis and tailored management.

Collagen type VI-related dystrophies (COL6-RD) are rare diseases with a wide phenotypic spectrum ranging from severe Ullrich’s congenital muscular dystrophy Ullrich congenital muscular dystrophy to much milder Bethlem myopathy Both dominant and recessive forms of COL6-RD are caused by pathogenic variants in three collagen VI genes (COL6A1, COL6A2 and COL6A3). The prognosis of these diseases is variable and difficult to predict during early disease stages, especially since the genotype-phenotype correlation is not always clear. For this reason, studies with long-term follow-up of patients with genetically confirmed COL6-RD are still needed. In this study, we present phenotypic and genetic data from 25 patients (22 families) diagnosed with COL6-RD and followed at a single French center, in both adult and pediatric neurology departments. We describe three novel pathogenic variants and identify COL6A2:c.1970-9G>A as the most frequent variant in our series (29%). We also observe an accelerated progression of the disease in a subgroup of patients. This large series of rare disease patients provides essential information on phenotypic variability of COL6-RD patients as well as on frequency of pathogenic COL6A gene variants in Southern France, thus contributing to the phenotypic and genetic description of Collagen type VI-related dystrophies. [ABSTRACT FROM AUTHOR]

Collagen type VI-related dystrophies (COL6-RD) are rare diseases with a wide phenotypic spectrum ranging from severe Ullrich’s congenital muscular dystrophy Ullrich congenital muscular dystrophy to much milder Bethlem myopathy Both dominant and recessive forms of COL6-RD are caused by pathogenic variants in three collagen VI genes (COL6A1, COL6A2 and COL6A3). The prognosis of these diseases is variable and difficult to predict during early disease stages, especially since the genotype-phenotype correlation is not always clear. For this reason, studies with long-term follow-up of patients with genetically confirmed COL6-RD are still needed. In this study, we present phenotypic and genetic data from 25 patients (22 families) diagnosed with COL6-RD and followed at a single French center, in both adult and pediatric neurology departments. We describe three novel pathogenic variants and identify COL6A2:c.1970-9G>A as the most frequent variant in our series (29%). We also observe an accelerated progression of the disease in a subgroup of patients. This large series of rare disease patients provides essential information on phenotypic variability of COL6-RD patients as well as on frequency of pathogenic COL6A gene variants in Southern France, thus contributing to the phenotypic and genetic description of Collagen type VI-related dystrophies.

Pathogenetic mechanism recognition and proof-of-concept clinical trials were performed in our patients affected by collagen VI-related myopathies. This study, which included 69 patients, aimed to identify innovative clinical data to better design future trials. Among the patients, 33 had Bethlem myopathy (BM), 24 had Ullrich congenital muscular dystrophy (UCMD), 7 had an intermediate phenotype (INTM), and five had myosclerosis myopathy (MM). We obtained data on muscle strength, the degree of contracture, immunofluorescence, and genetics. In our BM group, only one third had a knee extension strength greater than 50% of the predicted value, while only one in ten showed similar retention of elbow flexion. These findings should be considered when recruiting BM patients for future trials. All the MM patients had axial and limb contractures that limited both the flexion and extension ranges of motion, and a limitation in mouth opening. The immunofluorescence analysis of collagen VI in 55 biopsies from 37 patients confirmed the correlation between collagen VI defects and the severity of the clinical phenotype. However, biopsies from the same patient or from patients with the same mutation taken at different times showed a progressive increase in protein expression with age. The new finding of the time-dependent modulation of collagen VI expression should be considered in genetic correction trials. [ABSTRACT FROM AUTHOR]

• Good phenotypic-genotypic correlation of 13 patients with collagen VI MD. • Most patients (80%) have dominant negative mutations in triple helical domain. • Transcriptomic evaluation suggest perturbation to skeletal muscle differentiation. Collagen VI-related myopathies are a group of disorders that cause muscle weakness and joint contractures with significant variability in disease severity among patients. Here we report the clinical and genetic characteristics of 13 Chinese patients. Detailed histological, radiological and muscle transcriptomic evaluations were also conducted for selected representative patients. Across the cohort, fifteen putative disease causal variants were identified in three genes encoding collagen VI subunits, COL6A1 (n=6), COL6A2 (n=5), and COL6A3 (n=4). Most of these variants (12/15, 80%) were dominant negative and occurred at the triple helical domain. The rest (3/15, 20%) were located at the C-terminus. Two previously unreported variants, an in-frame mutation (COL6A1 :c.1084_1092del) and a missense mutation (COL6A2 :c.811G>C), were also noted. The transcriptome data from the muscle biopsies of two patients in the study with dominant negative mutations [ COL6A2 :c.811G>C and COL6A1 :c.930+189C>T] supports the accepted aetiology of Collagen VI myopathy as dysfunction of the extracellular matrix. It also suggests there are perturbations to skeletal muscle differentiation and skeletal system development. It should be noted that although the phenotypes of patients can be mostly explained by the position and dominant-negative effect of the variants, exceptions and variability still exist and have to be reckoned with. This study provides valuable data explaining the varying severity of phenotypes among ethnically Chinese patients. [ABSTRACT FROM AUTHOR]

Collagen VI exerts several functions in the tissues in which it is expressed, including mechanical roles, cytoprotective functions with the inhibition of apoptosis and oxidative damage, and the promotion of tumor growth and progression by the regulation of cell differentiation and autophagic mechanisms. Mutations in the genes encoding collagen VI main chains, COL6A1, COL6A2 and COL6A3, are responsible for a spectrum of congenital muscular disorders, namely Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM) and myosclerosis myopathy (MM), which show a variable combination of muscle wasting and weakness, joint contractures, distal laxity, and respiratory compromise. No effective therapeutic strategy is available so far for these diseases; moreover, the effects of collagen VI mutations on other tissues is poorly investigated. The aim of this review is to outline the role of collagen VI in the musculoskeletal system and to give an update about the tissue-specific functions revealed by studies on animal models and from patients' derived samples in order to fill the knowledge gap between scientists and the clinicians who daily manage patients affected by collagen VI-related myopathies. [ABSTRACT FROM AUTHOR]

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

Abstract Background Collagen VI-related dystrophy spans a clinical continuum from severe Ullrich congenital muscular dystrophy to milder Bethlem myopathy. This disease is caused by causative variants in COL6A1, COL6A2, or COL6A3. Most reported causative variants are de novo; therefore, to identify possible associated causative variants, comprehensive large cohort studies are required for different ethnicities. Methods We retrospectively reviewed clinical information, muscle histology, and genetic analyses from 147 Japanese patients representing 130 families, whose samples were sent for diagnosis to the National Center of Neurology and Psychiatry between July 1979 and January 2020. Genetic analyses were conducted by gene-based resequencing, targeted panel resequencing, and whole exome sequencing, in combination with cDNA analysis. Results Of a total of 130 families with 1–5 members with collagen VI-related dystrophy, 120 had mono-allelic and 10 had bi-allelic variants in COL6A1, COL6A2, or COL6A3. Among them, 60 variants were in COL6A1, 57 in COL6A2, and 23 in COL6A3, including 37 novel variants. Mono-allelic variants were classified into four groups: missense (69, 58%), splicing (40, 33%), small in-frame deletion (7, 6%), and large genomic deletion (4, 3%). Variants in the triple helical domains accounted for 88% (105/120) of all mono-allelic variants. Conclusions We report the causative variant profile of a large set of Japanese cases of collagen VI-related dystrophy. This dataset can be used as a reference to support genetic diagnosis and variant-specific treatment.

Objectives: Collagen-VI-related myopathies are caused by both dominant and recessive mutations in the three collagen-VI-related genes (COL6A1, COL6A2, and COL6A3) and present as two different major clinical entities; Bethlem myopathy and Ullrich congenital muscular dystrophy. Methods: In this study, we evaluated the clinical, pathologic, and genetic features of 8 patients with Bethlem myopathy from 3 families. Results: We inspected disease course differences with age and mutations. Different variants in COL6A1 and COL6A2 genes were detected. Muscle MRI of the lower limbs showed a specific pattern of muscle involvement with variable severity of fatty infiltration. One family had essential hypertension. Conclusion: Genotype-phenotype correlation studies are critical in determining gene or mutation-targeted therapies, patient follow-up, severity and progression prediction, and genetic counselling.

Objectives: Collagen-VI-related myopathies are caused by both dominant and recessive mutations in the three collagen-VI-related genes (COL6A1, COL6A2, and COL6A3) and present as two different major clinical entities; Bethlem myopathy and Ullrich congenital muscular dystrophy. Methods: In this study, we evaluated the clinical, pathologic, and genetic features of 8 patients with Bethlem myopathy from 3 families. Results: We inspected disease course differences with age and mutations. Different variants in COL6A1 and COL6A2 genes were detected. Muscle MRI of the lower limbs showed a specific pattern of muscle involvement with variable severity of fatty infiltration. One family had essential hypertension. Conclusion: Genotype-phenotype correlation studies are critical in determining gene or mutation-targeted therapies, patient follow-up, severity and progression prediction, and genetic counselling. [ABSTRACT FROM AUTHOR]

Introduction. Bethlem myopathy is a rare subtype of congenital muscular dystrophy characterized by progressive muscle weakness and joint contractures. It is a milder phenotype of the spectrum of collagen VI-related myopathies, which are caused by mutations in genes encoding collagen VI proteins, namely COL6A1, COL6A2, or COL6A3. Clinical manifestation may begin at any time from the prenatal period to late adulthood, presenting a range of symptoms from mild muscle weakness to severe disability impacting the individual's mobility and quality of life. Case description. A 13-year-old patient presented with progressive weakness affecting both arms and legs, accompanied by an inability to stand flat-footed, walk on heels, squat and rise, and experiencing calf pain after walking longer distances. Additionally, the patient struggled with lifting and carrying various objects. Since the age of 2, an abnormal gait characterized by toe walking had been observed. At 11 years old, the patient underwent Achilles tendon surgery. Physical examination revealed scapular winging, elbow contractures, muscle atrophy in the arms and legs, and follicular hyperkeratosis in the humeral and thigh regions. Elevated levels of creatine kinase were noted, along with myopathic changes evident on electroneuromyography. At 15 years old, muscle biopsy demonstrated myopathic changes without dystrophinopathy-related immunohistochemical alterations. At the age of 20, next generation sequencing analysis revealed a heterozygous variant c.1053+1G>A; p.(?) of COL6A2 gene (NM_001849.4) which is reported as pathogenic. The patient's mother, her mother, brother, and niece reported similar symptoms. Segregation analysis in affected family members revealed the same variant of COL6A2 gene. Conclusions. We present a rare case of familial Bethlem myopathy with symptoms evident from early childhood. Understanding the clinical presentation and progression of Bethlem myopathy in children is crucial for early detection, effective management, and genetic counseling. We highlight the importance of a multidisciplinary approach involving neurologists, orthopedist, geneticists, and rehabilitation specialists in providing care for patients with Bethlem myopathy, particularly in pediatric cases where early intervention can significantly impact quality of life. [ABSTRACT FROM AUTHOR]

Abstract Background Collagen VI-related myopathies are a spectrum of muscular diseases with features of muscle weakness and atrophy, multiple contractures of joints, distal hyperextensibility, severe respiratory dysfunction and cutaneous alterations, attributable to mutations in the COL6A1, COL6A2, and COL6A3 genes. However, no case of collagen VI mutations with hematuria has been reported. We report a 14-year-old boy who had both Bethlem myopathy and recurrent hematuria and who carried a known de novo COL6A1 missense mutation c.877G > A (p.G293R). Case presentation The patient was a 14-year-old boy presenting with muscle weakness from 3 years of age without any family history. Six months before admission, he developed recurrent gross hematuria, three bouts in total, with the presence of blood clots in the urine. Next-generation sequencing of his whole-exome was performed. The result of sequencing revealed a de novo heterozygous G-to-A nucleotide substitution at position 877 in exon 10 of the COL6A1 gene. After treatment, the hematuria healed, but the muscle weakness failed to improve. Conclusions Hematuria in Bethlem myopathy can be caused by COL6 mutations, which may be related to the aberrant connection between collagen VI and collagen IV.

Background: Collagen VI-related dystrophy spans a clinical continuum from severe Ullrich congenital muscular dystrophy to milder Bethlem myopathy. This disease is caused by causative variants in COL6A1, COL6A2, or COL6A3. Most reported causative variants are de novo; therefore, to identify possible associated causative variants, comprehensive large cohort studies are required for different ethnicities.Methods: We retrospectively reviewed clinical information, muscle histology, and genetic analyses from 147 Japanese patients representing 130 families, whose samples were sent for diagnosis to the National Center of Neurology and Psychiatry between July 1979 and January 2020. Genetic analyses were conducted by gene-based resequencing, targeted panel resequencing, and whole exome sequencing, in combination with cDNA analysis.Results: Of a total of 130 families with 1-5 members with collagen VI-related dystrophy, 120 had mono-allelic and 10 had bi-allelic variants in COL6A1, COL6A2, or COL6A3. Among them, 60 variants were in COL6A1, 57 in COL6A2, and 23 in COL6A3, including 37 novel variants. Mono-allelic variants were classified into four groups: missense (69, 58%), splicing (40, 33%), small in-frame deletion (7, 6%), and large genomic deletion (4, 3%). Variants in the triple helical domains accounted for 88% (105/120) of all mono-allelic variants.Conclusions: We report the causative variant profile of a large set of Japanese cases of collagen VI-related dystrophy. This dataset can be used as a reference to support genetic diagnosis and variant-specific treatment. [ABSTRACT FROM AUTHOR]

Pericytes are a distinct type of cells interacting with endothelial cells in blood vessels and contributing to endothelial barrier integrity. Furthermore, pericytes show mesenchymal stem cell properties. Muscle-derived pericytes can demonstrate both angiogenic and myogenic capabilities. It is well known that regenerative abilities and muscle stem cell potential decline during aging, leading to sarcopenia. Therefore, this study aimed to investigate the potential of pericytes in supporting muscle differentiation and angiogenesis in elderly individuals and in patients affected by Ullrich congenital muscular dystrophy or by Bethlem myopathy, two inherited conditions caused by mutations in collagen VI genes and sharing similarities with the progressive skeletal muscle changes observed during aging. The study characterized pericytes from different age groups and from individuals with collagen VI deficiency by mass spectrometry-based proteomic and bioinformatic analyses. The findings revealed that aged pericytes display metabolic changes comparable to those seen in aging skeletal muscle, as well as a decline in their stem potential, reduced protein synthesis, and alterations in focal adhesion and contractility, pointing to a decrease in their ability to form blood vessels. Strikingly, pericytes from young patients with collagen VI deficiency showed similar characteristics to aged pericytes, but were found to still handle oxidative stress effectively together with an enhanced angiogenic capacity.

Bethlem myopathy is a collagen VI‐related myopathy. Collagen VI is primarily not only associated with the extracellular matrix of skeletal muscle, but is also found in the skin, blood vessels, and other organs. Dermatologic findings described for Bethlem myopathy include follicular hyperkeratosis and abnormal scar formation, although clinical and histopathologic photographs remain elusive in the literature. We present a case of atypical keratosis pilaris‐like follicular lesions in a patient with Bethlem myopathy and provide histopathologic correlation to better characterize the development of skin lesions in this rare neuromuscular disease. [ABSTRACT FROM AUTHOR]

Bethlem myopathy is a kind of collagen VI related myopathy which affects proximal skeletal muscles and leads to gait disturbance and multiple joint contractures with an onset in the first two decades of life. Lung function impairment (respiratory muscle and diaphragmatic weakness, ventilatory restriction, hypoxaemia and hypercapnia) and respiratory failure are part of the clinical spectrum and can occur in ambulatory patients. We carried out whole exome sequencing (WES) in combination with neuromuscular diseases-associated genes-filtering to detect the possible causative mutation(s) in a Korean family with Bethlem myopathy. An electrodiagnostic study showed myopathic pattern (normal nerve conduction study, and early recruitment and short amplitude muscle unit action potentials) in the proband. Coexistence of digenic mutations in the collagen VI genes (COL6A1 and COL6A3) was identified by WES in the proband only: heterozygous missense mutations of the COL6A1 (NM_001848.2: c.823G > T, p.Gly275Trp; rs1556425467) and of the COL6A3 genes (NM_004369.3: c.9349G > A, p.Asp3117Asn; rs1226664855). COL6A3 mutation may be candidate as disease-associated variant, as far as it was found only in the proband harboring another heterozygous mutation in COL6A1 gene, previously reported as different pathogenic mutations (p.Gly275Arg and p.Gly275Glu) at the same codon in Bethlem myopathy. Our findings suggest that the coexistence of these digenic mutations is rare, but it may be used for the risk evaluation of individuals with a possible susceptibility to Bethlem myopathy. Taken together, genetic diagnosis using WES is a useful approach for the identification of pathogenic mutations associated with Bethlem myopathy. [ABSTRACT FROM AUTHOR]

Using MRI, the main aim was to (1) map the pattern of muscle involvement by assessing fat fraction and (2) investigate frequency of target and sandwich signs in 42 muscles of patients with Bethlem myopathy (BM). Fifteen BM patients were included. Results were compared to findings in 8 healthy controls and 50 patients with four other types of muscular dystrophies. All muscles, except one, showed higher fat fraction in BM patients vs healthy controls (p < 0.05) with an overall proximal muscle affection, resembling a limb girdle-like pattern. In moderate patients, the specificity was 90% for the sandwich sign and 98% for the target sign. Sensitivity for both signs was 100%. Twelve BM patients had sandwich sign in other muscles than the vastus lateralis. Muscle strength correlated with fat fraction. Mean fat fraction in the psoas major was 39% in BM patients, which was considerably higher than in 3 of the 4 muscular dystrophy control diseases. The presence of signs in conjunction with severe affection of the psoas major muscle can serve as a diagnostic tool in BM. The high level of STIR lesions in muscles of BM patients warrants further investigations. [ABSTRACT FROM AUTHOR]

Mutations in the genes that code for type VI collagen can lead to what are known as the collagenopathies (collagen VI myopathies), such as Bethlem myopathy (BTHLM1), which affect structural tissues like muscles and tendons. We present the case of a young female and her two relatives, who were discovered to share the autosomal dominant COL6A3 mutation and whose presentation in clinic varied from mild to severe. Type VI collagenopathies represent a clinically and genetically heterogeneous spectrum of disorders generally characterized by muscle weakness and joint contractures. We highlight the importance of examining close relatives whenever possible and documenting a pedigree prior to proceeding with further electromyography (EMG) and lab work up, which includes obtaining genetic testing in order to reach a unifying diagnosis. The proband (L.C.) reported challenges with activities of daily living due to distal hand weakness, had significant findings on neuromuscular exam, and had abnormalities on needle EMG testing. Five of her relatives were reported to have weakness and trouble with day-to-day function. Her mother (M.C.) and her maternal grandfather (W.C.) were able to be examined in person and had the condition genetically confirmed.

The combination of autosomal dominant, early onset Paget disease of bone (PDB) and muscular dystrophy is an unusual disorder. We recently mapped the disorder in a large family from central Illinois with PDB and proximal limb-girdle type of muscular dystrophy (LGMD), and in 3 additional families with hereditary inclusion body myopathy (HIBM), Paget disease of bone and frontotemporal dementia, to a unique locus on chromosome 9p21.1-q12. The present study describes an unrelated 10-member family with autosomal dominant PDB and a scapuloperoneal type of muscular dystrophy. Clinical, biochemical, and radiological evaluations were performed to delineate clinical features in this family. Progression of the muscular dystrophy begins with weakness in the distal muscles of the legs accompanied by foot drop. EMG and muscle biopsy are compatible with a primary dystrophy. Onset of Paget disease is early, at a mean age of 41 years, with initial distribution in the long bones and eventual infiltration of the spine and pelvis. Creatine phosphokinase (CPK) and alkaline phosphatase levels are elevated in affected individuals. Molecular analyses excluded all known loci for Paget disease of bone, scapuloperoneal muscular dystrophy (SPMD), fascioscapulohumeral muscular dystrophy (FSH), amyotrophic lateral sclerosis (ALS), Bethlem myopathy, two forms of autosomal dominant limb-girdle muscular dystrophy (LGMD), and the critical region for LGMD or HIBM/PDB on chromosome 9p21.1-q12, thus providing evidence for genetic heterogeneity among families with the unique combination of muscular dystrophy and Paget disease of bone.

Collagen VI-related myopathy is a group of disorders affecting skeletal muscles and connective tissue. The most common symptoms are muscle weakness and joint deformities which limit the movement and progress over time. Several forms of collagen VI-related myopathies have been described: Bethlem myopathy, an intermediate form and Ullrich congenital muscular dystrophy, which is the most severe. Here we report a novel de novo c.1056+3A>C substitution in intron 14 of the COL6A1 gene encoding alpha-chains of collagen VI in a 13-year-old girl suffering from collagen VI (ColVI) myopathy. Analysis performed on cDNA generated from the RNA obtained from the patient’s blood cells showed that the reported variant leads to the entire exon 14 skipping and probably results in an in-frame deletion of 18 amino acids of the COL6A1 protein. Clinical presentation, abnormal secretion of the collagen demonstrated in muscle biopsy and the COL6A1 c.1056+3A>C mutation justify classification of the presented case as ColVI myopathy with moderate-progressive course. Analysis of the literature indicates that the donor splice site of COL6A1 intron 14, associated with the phenotype of Bethlem myopathy or intermediate form, is a hot spot for ColVI myopathies.

• Bethlem myopathy (BM) may be inherited in a recessive manner. • Mutations may cause both Collagen VI reduction and impaired secretion and assembly. • The occurrence of recessive inherited BM implies changes in genetic counselling. Bethlem myopathy represents the milder form of the spectrum of Collagen VI-related dystrophies, which are characterized by a clinical continuum between the two extremities, the Bethlem myopathy and the Ullrich congenital muscular dystrophy, and include less defined intermediate phenotypes. Bethlem myopathy is mainly an autosomal dominant disorder and the causing mutations occur in the COL6A genes encoding for the α1 (COL6A1), α2 (COL6A2) and α3 (COL6A3) chains. However, few cases of recessive inheritance have been also reported. We here describe clinical, genetic and functional findings in a recessive Bethlem myopathy family harbouring two novel pathogenic mutations in the COL6A2 gene. Two adult siblings presented with muscle weakness and wasting, elbows and Achilles tendon retractions, lumbar hyperlordosis, waddling gait and positive Gowers' sign. Muscle biopsy showed a dystrophic pattern. Molecular analysis of the COL6A2 gene revealed the novel paternally-inherited nonsense p.Gln889* mutation and the maternally-inherited p.Pro260_Lys261insProPro small insertion. Fibroblast studies in both affected patients showed the concomitant reduction in the amount of normal Collagen VI (p.Gln889*) and impairment of Collagen VI secretion and assembly (p.Pro260_Lys261insProPro). Each of the two variants behave as a recessive mutation as shown by the asymptomatic heterozygous parents, while their concomitant effects determined a relatively mild Bethlem myopathy phenotype. This study confirms the occurrence of recessive inherited Bethlem myopathy and expands the genetic heterogeneity of this group of muscle diseases. [ABSTRACT FROM AUTHOR]

Introduction: Bethlem myopathy is caused by dysfunctional collagen VI assembly, leading to varying degrees of hyperlaxity, contractures and muscle weakness. Previous studies demonstrate that cardiovascular training is safe and beneficial in patients with myopathies. However, exercise exacerbates the dystrophic phenotype in collagen VI-knockout mice.Methods: Six men with Bethlem myopathy were included (4 training; 2 controls). After training, 2 patients detrained. Patients performed 10 weeks of home-based, moderate-intensity exercise monitored by a pulse-watch. The primary outcome was change in peak oxygen uptake (VO2peak ). Secondary outcomes were performances in functional tests.Results: VO2peak improved in the training group (16%, P = 0.017). Detraining led to regression of VO2peak toward baseline values (-8%; P = 0.03). No change was seen in the control group (-7%; P = 0.47). Performance in functional tests did not change significantly. Creatine kinase values were stable during the study.Conclusions: Moderate-intensity exercise seems to safely improve oxidative function in patients with Bethlem myopathy. Muscle Nerve 60: 183-188, 2019. [ABSTRACT FROM AUTHOR]

Background: Bethlem myopathy represents the milder phenotype of collagen type VI-related myopathies. However, clinical manifestations are highly variable among patients and no phenotype-genotype correlation has been described. We aim to analyse the clinical, pathological and genetic features of a series of patients with Bethlem myopathy, and we describe seven new mutations.Methods: A series of 16 patients with the diagnosis of Bethlem myopathy were analyzed retrospectively from their medical records for clinical, creatine kinase (CK), muscle biopsy, and muscle magnetic resonance (MRI) data. Genetic testing was performed through next-generation sequencing of custom amplicon-based targeted genes panel of myopathies. Mutations were confirmed by Sanger sequencing.Results: The most frequent phenotype consisted of proximal limb weakness associated with interphalangeal and wrists contractures. However, cases with isolated contractures or isolated myopathy were found. CK levels did not correlate with severity of the disease. The most frequent mutation was the COL6A3 variant c.7447A>G, p.Lys2486Glu, with either an homozygous or compound heterozygous presentation. Five new mutations were found in COL6A1 gene and other two in COL6A3 gene, all of them with a dominant heritability pattern. From these, a new COL6A1 mutation (c.1657G>A, p.Glu553Arg) was related to an oligosymptomatic phenotype with predominating contractures in the absence of weakness and a normal muscle MRI. Finally, the most common COL6A1 mutation reported to date that leads to an Ullrich phenotype (c. 868G>A, p.Gly290Arg), has been found here as Bethlem presentation.Conclusions: Manifestations of Bethlem myopathy are quite variable, so either contractures or weakness may be lacking, and no phenotype-genotype associations can be brought. [ABSTRACT FROM AUTHOR]

Pregnancy poses significant physiological demands, and women of extreme short stature may be particularly at risk of complications. Described here are two pregnancies in a woman who was 130 cm tall with a body mass index of 12 kg/m2 and the maternal and neonatal outcomes. The challenges encountered in the care of our patient included cardiorespiratory compromise, management of medication dosing, management of delivery and bleeding risk. [ABSTRACT FROM AUTHOR]

Mutations in collagen VI genes cause two major clinical myopathies, Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD), and the rarer myosclerosis myopathy. In addition to congenital muscle weakness, patients affected by collagen VI-related myopathies show axial and proximal joint contractures, and distal joint hypermobility, which suggest the involvement of tendon function. To gain further insight into the role of collagen VI in human tendon structure and function, we performed ultrastructural, biochemical, and RT-PCR analysis on tendon biopsies and on cell cultures derived from two patients affected with BM and UCMD. In vitro studies revealed striking alterations in the collagen VI network, associated with disruption of the collagen VI-NG2 (Collagen VI-neural/glial antigen 2) axis and defects in cell polarization and migration. The organization of extracellular matrix (ECM) components, as regards collagens I and XII, was also affected, along with an increase in the active form of metalloproteinase 2 (MMP2). In agreement with the in vitro alterations, tendon biopsies from collagen VI-related myopathy patients displayed striking changes in collagen fibril morphology and cell death. These data point to a critical role of collagen VI in tendon matrix organization and cell behavior. The remodeling of the tendon matrix may contribute to the muscle dysfunction observed in BM and UCMD patients.

Bethlem myopathy, the mild form of collagen Ⅵ‐related myopathy, gradually affects pulmonary function without causing symptoms. We report a case of a 38‐year‐old woman presenting with subacute deterioration of hypercapnic respiratory failure following pneumonia. She had posterior instrumentation and fusion for scoliosis during adolescence. Mild muscle weakness of trunk and proximal lower limbs, representing atrophic changes in imaging, and flexion contractures were present. The muscle pathology showed moderate variation in fiber size with mild endomysial fibrosis. The heterozygous COL6A1 mutation was identified. We made the diagnosis of collagen Ⅵ‐related myopathy. Noninvasive positive pressure ventilation improved the respiratory failure. [ABSTRACT FROM AUTHOR]

Abstract Mutations in the three canonical collagen VI genes, COL6A1 , COL6A2 and COL6A3 , cause a spectrum of muscle disease from Bethlem myopathy at the mild end to the severe Ullrich congenital muscular dystrophy. Mutations can be either dominant or recessive and the resulting clinical severity is influenced by the way mutations impact the complex collagen VI assembly process. Most mutations are found towards the N-terminus of the triple helical collagenous domain and compromise extracellular microfibril assembly. Outside the triple helix collagen VI is highly polymorphic and discriminating mutations from rare benign changes remains a major diagnostic challenge. Collagen VI deficiency alters extracellular matrix structure and biomechanical properties and leads to increased apoptosis and oxidative stress, decreased autophagy, and impaired muscle regeneration. Therapies that target these downstream consequences have been tested in a collagen VI null mouse and also in small human trials where they show modest clinical efficacy. An important role for collagen VI in obesity, cancer and diabetes is emerging. A major barrier to developing effective therapies is the paucity of information about how collagen VI deficiency in the extracellular matrix signals the final downstream consequences – the receptors involved and the intracellular messengers await further characterization. Highlights • Collagen VI mutations produce mild to severe muscular dystrophies with skin and tendon involvement. • The mutations compromise collagen VI assembly and alter extracellular matrix structure and biomechanical properties. • We discuss the downstream cellular consequences and how these could be targeted therapeutically. • We review emerging roles for collagen VI in cancer, obesity and diabetes. [ABSTRACT FROM AUTHOR]

The synaptic cleft of the neuromuscular junction (NMJ) consists of a highly specialized extracellular matrix (ECM) involved in synapse maturation, in the juxtaposition of pre- to post-synaptic areas, and in ensuring proper synaptic transmission. Key components of synaptic ECM, such as collagen IV, perlecan and biglycan, are binding partners of one of the most abundant ECM protein of skeletal muscle, collagen VI (ColVI), previously never linked to NMJ. Here, we demonstrate that ColVI is itself a component of this specialized ECM and that it is required for the structural and functional integrity of NMJs. In vivo, ColVI deficiency causes fragmentation of acetylcholine receptor (AChR) clusters, with abnormal expression of NMJ-enriched proteins and re-expression of fetal AChRγ subunit, both in Col6a1 null mice and in patients affected by Ullrich congenital muscular dystrophy (UCMD), the most severe form of ColVI-related myopathies. Ex vivo muscle preparations from ColVI null mice revealed altered neuromuscular transmission, with electrophysiological defects and decreased safety factor (i.e., the excess current generated in response to a nerve impulse over that required to reach the action potential threshold). Moreover, in vitro studies in differentiated C2C12 myotubes showed the ability of ColVI to induce AChR clustering and synaptic gene expression. These findings reveal a novel role for ColVI at the NMJ and point to the involvement of NMJ defects in the etiopathology of ColVI-related myopathies. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to analyze the clinical and genetic characteristics of collagen VI-related myopathy.Methods: We analyzed the clinical course and mutation spectrum in patients with collagen VI gene mutations among our congenital muscular dystrophy cohort.Results: Among 24 patients with mutations in collagen VI coding genes, 13 (54.2%) were categorized as Ullrich type, and 11 (45.8%) as non-Ullrich type. Congenital orthopedic problems were similarly observed in both types, yet multiple joint contractures were found only in the Ullrich type. Clinical courses and pathology findings varied between patients. Mutations in COL6A1, COL6A2, and COL6A3 were found in 15 (65%), 3 (13%), and 5 (22%) patients, respectively, without genotype-phenotype association. Five novel variants were detected.Discussion: We verified clinical heterogeneity of collagen VI-related myopathy, which emphasizes the importance of genetic testing. Genotype-phenotype association or early predictors for progression were not identified. Multiple joint contractures predict rapid deterioration. Muscle Nerve 58: 381-388, 2018. [ABSTRACT FROM AUTHOR]

Collagen VI‐related myopathy, caused by pathogenic variants in the genes encoding collagen VI, represents a clinical continuum from Ullrich congenital muscular dystrophy (UCMD) to Bethlem myopathy (BM). Clinical data of 60 probands and their family members were collected and muscle biopsies of 26 patients were analyzed. COL6A1, COL6A2 and COL6A3 exons were analyzed by direct sequencing or next generation sequencing (NGS). Sixty patients were characterized by delayed motor milestones, muscle weakness, skin and joint changes with 40 UCMD and 20 BM. Muscle with biopsies revealed dystrophic changes and showed completely deficiency of collagen VI or sarcolemma specific collagen VI deficiency. We identified 62 different pathogenic variants in these 60 patients, with 34 were first reported while 28 were previously known; 72 allelic pathogenic variants in COL6A1 (25/72, 34.7%), COL6A2 (33/72, 45.8%) and COL6A3 (14/72, 19.4%). We also found somatic mosaic variant in the parent of 1 proband by personal genome machine amplicon deep sequencing for mosaicism. Here we provide clinical, histological and genetic evidence of collagen VI‐related myopathy in 60 Chinese patients. NGS is a valuable approach for diagnosis and accurate diagnosis provides useful information for genetic counseling of related families. [ABSTRACT FROM AUTHOR]

Introduction: Mutation in the collagen XII gene (COL12A1) was recently reported to induce Bethlem myopathy. We describe a family affected by collagen XII-related myopathy in 3 generations.Methods: Systematic interview, clinical examination, skin biopsies, and MRI of muscle were used.Results: The phenotype was characterized by neonatal hypotonia, contractures, and delayed motor development followed by resolution of contractures and a motor performance limited by reduced endurance. DNA analyses revealed a novel donor splice-site mutation in COL12A1 (c.8100 + 2T>C), which segregated with clinical affection and abnormal collagen XII retention in fibroblasts. MRI disclosed a selective wasting of the rectus femoris muscle.Discussion: COL12A1 mutations should be considered in patients with a mild Bethlem phenotype who present with selective wasting of the rectus femoris, absence of the outside-in phenomenon on MRI, and abnormal collagen XII retention in fibroblasts. Muscle Nerve 57: 1026-1030, 2018. [ABSTRACT FROM AUTHOR]

Collagen VI-related myopathy is a group of disorders affecting skeletal muscles and connective tissue. The most common symptoms are muscle weakness and joint deformities which limit the movement and progress over time. Several forms of collagen VI-related myopathies have been described: Bethlem myopathy, an intermediate form and Ullrich congenital muscular dystrophy, which is the most severe. Here we report a novel de novo c.1056+3A>C substitution in intron 14 of the COL6A1 gene encoding alpha-chains of collagen VI in a 13-year-old girl suffering from collagen VI (ColVI) myopathy. Analysis performed on cDNA generated from the RNA obtained from the patient's blood cells showed that the reported variant leads to the entire exon 14 skipping and probably results in an in-frame deletion of 18 amino acids of the COL6A1 protein. Clinical presentation, abnormal secretion of the collagen demonstrated in muscle biopsy and the COL6A1 c.1056+3A>C mutation justify classification of the presented case as ColVI myopathy with moderate-progressive course. Analysis of the literature indicates that the donor splice site of COL6A1 intron 14, associated with the phenotype of Bethlem myopathy or intermediate form, is a hot spot for ColVI myopathies. [ABSTRACT FROM AUTHOR]

Introduction: Mutations in the COL12A1 (collagen, type XII, alpha 1) gene have been described in a milder Bethlem-like myopathy in 6 patients from 3 families (dominant missense), and in a severe congenital form with failure to attain ambulation in 2 patients in a single pedigree (recessive loss-of-function).Methods: We describe an 8-year-old girl of Polish origin who presented with profound hypotonia and joint hyperlaxity at birth after a pregnancy complicated by oligohydramnios and intrauterine growth retardation.Results: We identified a novel, potentially pathogenic heterozygous missense COL12A1 c.8329G>C (p.Gly2777Arg) variant using a targeted sequencing panel. Patient fibroblast studies confirmed intracellular retention of the COL12A1 protein, consistent with a dominant-negative mutation.Conclusions: As our patient showed a more intermediate phenotype, this case expands the phenotypic spectrum for COL12A1 disorders. So far, COL12A1 disorders seem to cover much of the severity range of an Ehlers-Danlos/Bethlem-like myopathy overlap syndrome associated with both connective tissue abnormalities and muscle weakness. Muscle Nerve 55: 277-281, 2017. [ABSTRACT FROM AUTHOR]