Miopatías relacionadas a colágeno VI: cuando sospecharlas, cómo identificarlas: aporte de la resonancia magnética muscular / Collagen VI related myopathies: when to suspect, how to identify: the contribution of muscle magnetic resonance

Resumen: Las miopatías secundarias a mutaciones en el colágeno VI (M-COLVI) son las más frecuentes en el hemisferio norte, afectando población adulta y pediátrica. No existen datos de su prevalencia en Latinoamérica. Se caracterizan por presentar una gran variabilidad clínica, desde fenotipos severos, como la distrofia muscular congénita de Ullrich (DMCU), a intermedios y leves como la Miopatía de Bethlem (MB). Su inicio también es variable y se extiende desde el período de recién nacido hasta la vida adulta. Dada la presencia de hiperlaxitud articular, el diagnóstico diferencial se debe realizar con diversas enfermedades del tejido conectivo. El algoritmo diagnóstico clásico en muchos pacientes ha sido insuficiente para orientar el estudio genético de forma adecuada, y a partir de esto la resonancia magnética muscular ha emergido como una herramienta de gran utilidad para una mejor aproxima ción diagnóstica de ésta y otras patologías musculares. Esta revisión tiene como objetivo examinar las formas de presentación, características clínicas, estudio diagnóstico específico, diagnóstico dife rencial y manejo de una de las patologías musculares herediatarias más frecuentes, con énfasis en el aporte de la resonancia magnética muscular.

Abstract: Myopathies secondary to collagen VI mutations (COLVI-M) are the most frequent in the northern hemisphere, affecting the adult and pediatric population. There are no data on its prevalence in Latin America. They are characterized by a great clinical variability, from severe phenotypes, such as Ullrich congenital muscular dystrophy (UCMD), to intermediate and mild ones such as Bethlem myopathy (BM). Its onset is also variable and extends from the neonatal period to adulthood. Given the presence of joint hypermobility, the differential diagnosis should be made with various connective tissue diseases. The classical diagnostic algorithm in many patients has been insufficient to guide the genetic study in an adequate way, and from this the muscular magnetic resonance imaging has emerged as a very useful tool for a better diagnostic approach of this and other muscular pathologies. This ob jective of this review is to study the forms of presentation, clinical characteristics, specific diagnostic study, differential diagnosis and management of one of the most frequent hereditary muscular patho logies, with emphasis on the contribution of muscle magnetic resonance imaging.

A Family of Bethlem Myopathy Caused by a Heterozygous COL6A1 Mutation

Collagen-VI-related myopathies are caused by mutations in the COL6A1, COL6A2, and COL6A3 and are known to have a wide phenotypic spectrum, including Bethlem myopathy, Ullrich congenital muscular dystrophy, intermediate phenotype, and limb-girdle muscular dystrophy. These patients present with joint hyperextensibility and/or contractures as well as skin changes and muscle weakness, and so clinicians need to notice those extramuscular symptoms in order to achieve a correct diagnosis. We describe the clinical, pathological, and radiological features in a family with Bethlem myopathy caused by a COL6A1 mutation.

Distrofia muscular congênita de Ullrich moderadamente progressiva / Moderately progressive Ullrich congenital muscular dystrophy

OBJETIVOS: Descrever características clínicas e genéticas da distrofia muscular congênita de Ullrich (DMCU), e relatar o caso de um paciente diagnosticado com DMCU após uma exaustiva investigação, que incluiu análise imuno-histoquímica e genômica do colágeno tipo VI. DESCRIÇÃO: Este estudo baseou-se na avaliação clínica e imuno-histoquímica do tecido muscular e na análise genômica dos fibroblastos dérmicos de um menino de 7 anos e meio, e do DNA dos seus pais. São discutidos aspectos clínicos e o diagnóstico diferencial com outras doenças. COMENTÁRIOS: O melhor conhecimento das distrofias musculares congênitas aumentará o número de diagnósticos corretos e abrirá novos horizontes para o tratamento dessas doenças. A avaliação genética dos pacientes com DMCU tem implicações relevantes para o prognóstico e o aconselhamento genético da família. É aconselhável divulgar essa doença na comunidade pediátrica, devido ao início precoce das manifestações clínicas e o fato de ser frequentemente mal diagnosticada ou não ser diagnosticada.

OBJECTIVES: To describe genetic and clinical features of Ullrich congenital muscular dystrophy (UCMD), and to report the case of a patient diagnosed with UCMD after an exhaustive investigation, which included collagen VI immunohistochemical and genomic analyses. DESCRIPTIONS: This study was based on clinical, immunohistochemical assessment of muscle tissue and genomic analysis of dermal fibroblasts of a 7 1/2-year old boy and of the DNA of his parents. Clinical aspects and differential diagnosis with other disorders are discussed. COMMENTS: A better knowledge of congenital muscular dystrophies will improve the number of correct diagnoses and open new horizons for the treatment of such diseases. Genetic evaluation of UCMD patients has relevant implications for prognosis and genetic counseling of the family. The divulgation of this disorder in the pediatric community is advisable, because of the early onset of clinical manifestations and the fact that it is frequently misdiagnosed or not diagnosed at all.

Congenital muscular dystrophy. Part II: a review of pathogenesis and therapeutic perspectives / Distrofia muscular congênita. Parte II: revisão da patogênese e perspectivas terapêuticas

The congenital muscular dystrophies (CMDs) are a group of genetically and clinically heterogeneous hereditary myopathies with preferentially autosomal recessive inheritance, that are characterized by congenital hypotonia, delayed motor development and early onset of progressive muscle weakness associated with dystrophic pattern on muscle biopsy. The clinical course is broadly variable and can comprise the involvement of the brain and eyes. From 1994, a great development in the knowledge of the molecular basis has occurred and the classification of CMDs has to be continuously up dated. In the last number of this journal, we presented the main clinical and diagnostic data concerning the different subtypes of CMD. In this second part of the review, we analyse the main reports from the literature concerning the pathogenesis and the therapeutic perspectives of the most common subtypes of CMD: MDC1A with merosin deficiency, collagen VI related CMDs (Ullrich and Bethlem), CMDs with abnormal glycosylation of alpha-dystroglycan (Fukuyama CMD, Muscle-eye-brain disease, Walker Warburg syndrome, MDC1C, MDC1D), and rigid spine syndrome, another much rare subtype of CMDs not related with the dystrophin/glycoproteins/extracellular matrix complex.

As distrofias musculares congênitas (DMCs) são miopatias hereditárias geralmente, porém não exclusivamente, de herança autossômica recessiva, que apresentam grande heterogeneidade genética e clínica. São caracterizadas por hipotonia muscular congênita, atraso do desenvolvimento motor e fraqueza muscular de início precoce associada a padrão distrófico na biópsia muscular. O quadro clínico, de gravidade variável, pode também incluir anormalidades oculares e do sistema nervoso central. A partir de 1994, os conhecimentos sobre genética e biologia molecular das DMCs progrediram rapidamente, sendo a classificação continuamente atualizada. Os aspectos clínicos e diagnósticos dos principais subtipos de DMC foram apresentados no número anterior deste periódico, como primeira parte desta revisão. Nesta segunda parte apresentaremos os principais mecanismos patogênicos e as perspectivas terapêuticas dos subtipos mais comuns de DMC: DMC tipo 1A com deficiência de merosina, DMCs relacionadas com alterações do colágeno VI (Ullrich e Bethlem), e DMCs com anormalidades de glicosilação da alfa-distroglicana (DMC Fukuyama, DMC "Muscle-eye-brain" ou MEB, síndrome de Walker Warburg, DMC tipo 1C, DMC tipo 1D). A DMC com espinha rígida, mais rara e não relacionada com alterações do complexo distrofina-glicoproteínas associadas-matriz extracelular também será abordada quanto aos mesmos aspectos patogênicos e terapêuticos.

Congenital muscular dystrophy: part I: a review of phenotypical and diagnostic aspects / Distrofia muscular congênita: parte I: revisão dos aspectos fenotípicos e diagnósticos

The congenital muscular dystrophies (CMDs) are a group of genetically and clinically heterogeneous hereditary myopathies with preferentially autosomal recessive inheritance, that are characterized by congenital hypotonia, delayed motor development and early onset of progressive muscle weakness associated with dystrophic pattern on muscle biopsy. The clinical course is broadly variable and can comprise the involvement of the brain and eyes. From 1994, a great development in the knowledge of the molecular basis has occurred and the classification of CMDs has to be continuously up dated. We initially present the main clinical and diagnostic data concerning the CMDs related to changes in the complex dystrophin-associated glycoproteins-extracellular matrix: CMD with merosin deficiency (CMD1A), collagen VI related CMDs (Ullrich CMD and Bethlem myopathy), CMDs with abnormal glycosylation of alpha-dystroglycan (Fukuyama CMD, Muscle-eye-brain disease, Walker-Warburg syndrome, CMD1C, CMD1D), and the much rarer CMD with integrin deficiency. Finally, we present other forms of CMDs not related with the dystrophin/glycoproteins/extracellular matrix complex (rigid spine syndrome, CMD1B, CMD with lamin A/C deficiency), and some apparently specific clinical forms not yet associated with a known molecular mechanism. The second part of this review concerning the pathogenesis and therapeutic perspectives of the different subtypes of CMD will be described in a next number.

As distrofias musculares congênitas (DMCs) são miopatias hereditárias geralmente, porém não exclusivamente, de herança autossômica recessiva, que apresentam grande heterogeneidade genética e clínica. São caracterizadas por hipotonia muscular congênita, atraso do desenvolvimento motor e fraqueza muscular de início precoce associada a padrão distrófico na biópsia muscular. O quadro clínico, de gravidade variável, pode também incluir anormalidades oculares e do sistema nervoso central. A partir de 1994, os conhecimentos sobre genética e biologia molecular das DMCs progrediram rapidamente, sendo a classificação continuamente atualizada. Nesta revisão apresentaremos os principais aspectos clínicos e diagnósticos dos subtipos mais comuns de DMC associados com alterações do complexo distrofina-glicoproteínas associadas-matriz extracelular que são DMC com deficiência de merosina (DMC tipo 1A), DMCs relacionadas com alterações do colágeno VI (DMC tipo Ullrich e miopatia de Bethlem), DMCs com anormalidades de gliocosilação da alfa-distroglicana (DMC Fukuyama, DMC "Muscle-eye-brain" ou MEB, síndrome de Walker-Warburg, DMC tipo 1C, DMC tipo 1D), além da raríssima DMC com deficiência de integrina. Outras formas mais raras de DMC, não relacionadas com o complexo distrofina-glicoproteínas associadas-matriz extracelular também serão apresentadas (DMC com espinha rígida, DMC tipo 1B, DMC com deficiência de lamina A/C) e, finalmente, algumas formas clínicas com fenótipo aparentemente específico que ainda não estão associadas com um defeito molecular definido. A patogenia e as perspectivas terapêuticas dos principais subtipos de DMC serão apresentados em um próximo número, na segunda parte desta revisão.

A Family of Bethlem Myopathy

Bethlem myopathy (BM) is an early-onset benign autosomal dominant myopathy characterized by proximal muscle weakness and multiple contractures. It is caused by mutations in the three genes encoding collagen VI, which is a ubiquitous extracellular matrix protein forming a microfibrillar network in close association with the basement membrane. Here, we present a family with BM which is the first reported Korean case.

A Case of Ullrich's Disease / 대한소아신경학회지

Ullrich's disease is a congenital muscular dystrophy clinically characterized by generalized muscle weakness, multiple contractures of the proximal joints, and hyperextensibility of the distal joints. All the patients develop rigidity of spine, often assoicated with scoliosis, failure to thrive, and early and severe respiratory involvement, irrespective of their levels of motor function. Intellectual development is normal. The biopsied muscles show dystrophies including remarkable variation in the fiber size, notably proliferated endomysial connective tissues, and a lot of degenerated and regenerated fibers. The expression of merosin and dytrophin is normal. Recent studies have demonstrated that collagen VI is deficient in the muscles of the patients with Ullrich's disease, and some result from recessive mutations of the collagen VIalpha 2 gene(COL6A2). And a marked reduction of fibronectin receptors in the extracellular matrix of skin and cultured fibroblasts of these patients is also reported. These results suggest that collagen VI deficiency may lead to the reduction of fibronectin receptors and that any abnormalities of cell adhesion may be involved in the pathogenesis of the disease. A case of Ullrich's disease has not been reported yet in Korea. So, we describe a male patient with Ullrich's disease with a brief review of the literature.

Alteration in Extracellular Matrix Components in Preeclamptic Nephropathy

The preeclamptic nephropathy is characterized by swelling of endothelial cells, interposition of mesangial cells and matrix, subendothelial deposits of incompletely defined material, and thickening of the capillary walls. To determine the distribution of extracellular matrix (ECM) components in preeclamptic nephropathy, the immunohistochemical study was performed in ten renal biopsy cases using antisera to human type I, III, IV, and VI collagens, fibronectin, and laminin. In preeclamptic nephropathy, the accumulation of type IV and VI collagens, fibronectin was observed in moderate amount in the mesangium and, to some extent, in the thickened capillary walls, particularly in the subendothelial layer. In segmentally sclerotic lesions seen in six cases, the amount of type IV collagen was partly decreased, whereas those of type VI collagen and fibronectin were slightly increased. Type I collagen was expressed to a mild degree in the expanded mesangium and segmentally sclerotic lesions. The results suggest that the expression of ECM in the mesangium is increased in preeclamptic nephropathy, and the deposition of ECM components may be involved in the development and the reparative process of the characteristic glomerular lesions. The formation of sclerotic lesions may be linked to the alternative accumulation of ECM components.

Immunohistochemical Localization of Extracellular Matrix Components in Diabetic Nephropathy

Normal human glomerular basement membrane (GBM) and mesangial matrix (MM) contain several different basement membrane components in varying degrees. The characteristic morphological and ultrastructural changes in patients with diabetic nephropathy are the thickening of the GBM and the expansion of the MM. In order to investigate the changes of extracellular matrix components in diabetes, the immunohistochemical localization was performed in 17 cases with different degrees using antisera to human collagen types I, III, IV, VI, fibronectin, and laminin. The following results were obtained: 1. The reactivity for collagen IV was increased in expanded MM in the diffuse glomerulosclerosis (GS). With the progression to the nodule formation, collagen IV was prominently decreased in the peripheral area of the nodules. 2. Collagen VI was increased in GBM and MM in the diffuse GS, it was especially prominent in the expanded MM. With the progression to nodule formation, collagen VI was prominently increased in the periphery of the nodules. 3. Interstitial collagen I and III were not stained in many of the cases with the diffuse GS. With the progression to nodule formation, these were slightly expressed. A lamellar pattern of positive reaction was noted at the periphery of the late nodular lesions. 4. Fibronectin was increased in GBM & MM in the diffuse GS, it was especially intense in the MM. With the progression to the nodule formation, the reactivity of antibody to the fibronectin was decreased. 5. Laminin was weakly stained along the GBM & trace in the MM, but was not changed in the nodular GS. In summary, the expanded mesangial matrix in the diffuse GS showed a markedly increased staining for collagen IV, fibronectin and collagen VI. Less intense linear staining for collagen VI, fibronectin, laminin, collagen IV and collagen III was noted along the GBM. In the nodular GS, the composition of the early nodules resembled that of the diffuse GS. However, the late nodular lesion of the nodular GS revealed decreased reactivity for collagen IV and fibronectin at the periphery of the nodule, where collagen VI and interstitial collagen I and III were increased in laminated pattern.