Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In contrast with Steinert's disease (DM1), type 2 muscular dystrophy (DM2) is not known to be associated with a high prevalence of cardiac involvement. Our objective was to compare the results of detailed cardiac investigations in populations of DM2 and DM1 patients, and in controls. Thirty-eight DM2 patients (17 males; age=57.1+/-15.2years) were investigated for possible heart involvement, and their results compared with 76 age-sex matched DM1 patients and 76 controls. Cardiac abnormalities were present in 15 DM2 patients, including conductive defects in 14, systolic dysfunction in 6, supraventricular arrhythmias in 6 and stroke in 5 patients and were significantly more frequent than in controls. When compared to DM1 patients, conductive defects were less frequent, supraventricular arrhythmias had similar prevalence and there was a trend towards more frequent left ventricular dysfunction in DM2 patients. Our study suggests that systematic cardiac investigations should be recommended in these patients.
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PMID:Left ventricular dysfunction and cardiac arrhythmias are frequent in type 2 myotonic dystrophy: a case control study. 1948 39

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that is strongly associated with insulin resistance. Myotonic dystrophy (DM1) is the most common form of adult-onset muscular dystrophy, and there is a high frequency of insulin resistance due to insulin receptor mRNA splicing defects in muscle tissue. The frequency and predictors of NAFLD in this population have not been described. Thirty-six patients with DM1 were prospectively assessed for the presence of NAFLD and insulin resistance. NAFLD was defined by abnormal liver chemistry tests with ultrasound or pathologic evidence of steatosis in the absence of other liver disease. Abnormal liver chemistry tests were found in 44% of DM1 patients (mean ALT 73 +/- 21 U/L, AST 53 +/- 15 U/L), and 87% were attributable to NAFLD. Clinical predictors of NAFLD included increased insulin resistance by the homeostasis model assessment (HOMA) method (9.5 vs. 4.0 U, P = 0.03), elevated fasting insulin (40.4 vs. 16.1 microIU/ml, P = 0.03), abdominal obesity (98.6 vs. 90.8 cm, P = 0.03), elevated triglycerides (195.7 vs. 136.8 mg/dl, P = 0.02), and elevated total cholesterol (213.6 vs. 180.6 mg/dl, P = 0.02). NAFLD is very common and should be considered in the management of DM1. It is strongly associated with markers of insulin resistance and features of the metabolic syndrome. These findings support the role of peripheral insulin resistance in the pathogenesis of NAFLD.
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PMID:Frequency and predictors of nonalcoholic fatty liver disease in myotonic dystrophy. 1981 85

Myotonic muscular dystrophy types 1 and 2 (DM1 and DM2, respectively) are caused by expansions of repeating nucleotides in noncoding regions of RNA. In DM1, the expansion is an rCUG triplet repeat, whereas the DM2 expansion is an rCCUG quadruplet repeat. Both RNAs fold into hairpin structures with periodically repeating internal loops separated by two 5'GC/3'CG base pairs. The sizes of the loops, however, are different: the DM1 repeat forms 1 x 1 nucleotide UU loops while the DM2 repeat forms 2 x 2 nucleotide 5'CU/3'UC loops. DM is caused when the expanded repeats bind the RNA splicing regulator Muscleblind-like 1 protein (MBNL1), thus compromising its function. Therefore, one potential therapeutic strategy for these diseases is to prevent MBNL1 from binding the toxic RNA repeats. Previously, we designed nanomolar inhibitors of the DM2-MBNL1 interaction by modularly assembling 6'-N-5-hexyonate kanamycin A (K) onto a peptoid backbone. The K ligand binds the 2 x 2 pyrimidine-rich internal loops found in the DM2 RNA with high affinity. The best compound identified from that study contains three K modules separated by four propylamine spacing modules and is 20-fold selective for the DM2 RNA over the DM1 RNA. Because the modularly assembled K-containing compounds also bound the DM1 RNA, albeit with lower affinity, and because the loop size is different, we hypothesized that the optimal DM1 RNA binder may display K modules separated by a shorter distance. Indeed, here the ideal DM1 RNA binder has only two propylamine spacing modules separating the K ligands. Peptoids displaying three and four K modules on a peptoid scaffold bind the DM1 RNA with K(d)'s of 20 nM (3-fold selective for DM1 over DM2) and 4 nM (6-fold selective) and inhibit the RNA-protein interaction with IC(50)'s of 40 and 7 nM, respectively. Importantly, by coupling the two studies together, we have determined that appropriate spacing can affect binding selectivity by 60-fold (20- x 3-fold). The trimer and tetramer also bind approximately 13- and approximately 63-fold more tightly to DM1 RNAs than does MBNL1. The modularly assembled compounds are cell permeable and nontoxic as determined by flow cytometry. The results establish that for these two systems: (i) a programmable modular assembly approach can provide synthetic ligands for RNA with affinities and specificities that exceed those of natural proteins; and, (ii) the spacing of ligand modules can be used to tune specificity for one RNA target over another.
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PMID:Controlling the specificity of modularly assembled small molecules for RNA via ligand module spacing: targeting the RNAs that cause myotonic muscular dystrophy. 1990 40

DM (myotonic dystrophy) is a dominantly inherited genetic disorder that is the most common cause of muscular dystrophy in adults affecting 1 in 8500 individuals worldwide. Different microsatellite expansions in two loci cause different forms of the disease that share similar features: DM1 (DM type 1) is caused by a tri- (CTG) nucleotide expansion within the DMPK (dystrophia myotonica protein kinase) 3'-untranslated region and DM2 (DM type 2) is caused by a tetra- (CCTG) nucleotide expansion within intron 1 of the ZNF9 (zinc finger 9) gene. The pathogenic mechanism of this disease involves the RNA transcribed from the expanded allele containing long tracts of (CUG)(n) or (CCUG)(n). The RNA results in a toxic effect through two RNA-binding proteins: MBNL1 (muscleblind-like 1) and CUGBP1 (CUG-binding protein 1). In DM1, MBNL1 is sequestered on CUG repeat-containing RNA resulting in its loss-of-function, while CUGBP1 is up-regulated through a signalling pathway. The downstream effects include disrupted regulation of alternative splicing, mRNA translation and mRNA stability, which contribute to the multiple features of DM1. This review will focus on the RNA gain-of-function disease mechanism, the important roles of MBNL1 and CUGBP1 in DM1, and the relevance to other RNA dominant disorders.
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PMID:Pathogenic mechanisms of myotonic dystrophy. 1990 63

Myotonic dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults, affecting 1/8000 individuals. DM1 is a dominant disorder characterized by multisystemic clinical features affecting skeletal muscle, heart and the nervous and endocrine systems. DM1 is caused by an expansion of CTG trinucleotide repeats within the 3'-untranslated region (3'-UTR) of the DMPK gene. This repeat is polymorphic in normal individuals with alleles ranging from 5 to 37 in length. Repeats exceeding a threshold of approximately 50 and reaching up to a number of 4,000 result in disease. This review offers a detailed description of the scientific findings that have allowed the establishment of the molecular basis of the DM1 in the muscle and nervous systems. Currently, it is known that mutant DM1 transcript accumulates in the nucleus of muscle and neuronal cells sequestering nuclear proteins, such as splicing regulators and transcription factors to form nuclear foci that are observed under inmunofluorescence techniques. This event disturbs the expression of several muscular and neuronal genes impairing cell differentiation, which may explain the multiple symptoms of the disease. Finally, the main findings towards the development of a gene therapy for DM1 are discussed.
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PMID:[Pathogenesis of myotonic dystrophy type 1]. 2007 33

Myotonic dystrophy types 1 and 2 (DM1 and DM2) are forms of muscular dystrophy that share similar clinical and molecular manifestations, such as myotonia, muscle weakness, cardiac anomalies, cataracts, and the presence of defined RNA-containing foci in muscle nuclei. DM2 is caused by an expansion of the tetranucleotide CCTG repeat within the first intron of ZNF9, although the mechanism by which the expanded nucleotide repeat causes the debilitating symptoms of DM2 is unclear. Conflicting studies have led to two models for the mechanisms leading to the problems associated with DM2. First, a gain-of-function disease model hypothesizes that the repeat expansions in the transcribed RNA do not directly affect ZNF9 function. Instead repeat-containing RNAs are thought to sequester proteins in the nucleus, causing misregulation of normal cellular processes. In the alternative model, the repeat expansions impair ZNF9 function and lead to a decrease in the level of translation. Here we examine the normal in vivo function of ZNF9. We report that ZNF9 associates with actively translating ribosomes and functions as an activator of cap-independent translation of the human ODC mRNA. This activity is mediated by direct binding of ZNF9 to the internal ribosome entry site sequence (IRES) within the 5'UTR of ODC mRNA. ZNF9 can activate IRES-mediated translation of ODC within primary human myoblasts, and this activity is reduced in myoblasts derived from a DM2 patient. These data identify ZNF9 as a regulator of cap-independent translation and indicate that ZNF9 activity may contribute mechanistically to the myotonic dystrophy type 2 phenotype.
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PMID:ZNF9 activation of IRES-mediated translation of the human ODC mRNA is decreased in myotonic dystrophy type 2. 2017 32

There are currently two clinically and molecularly defined forms of myotonic dystrophy: (1) myotonic dystrophy type 1 (DM1), also known as 'Steinert's disease'; and (2) myotonic dystrophy type 2 (DM2), also known as proximal myotonic myopathy. DM1 and DM2 are progressive multisystem genetic disorders with several clinical and genetic features in common. DM1 is the most common form of adult onset muscular dystrophy whereas DM2 tends to have a milder phenotype with later onset of symptoms and is rarer than DM1. This review will focus on the clinical features, diagnosis and management of DM1 and DM2 and will briefly discuss the recent advances in the understanding of the molecular pathogenesis of these diseases with particular reference to new treatments using gene therapy.
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PMID:The myotonic dystrophies: diagnosis and management. 2017 1

Myotonic dystrophy type 1 (DM1), the most common form of adult muscular dystrophy, is caused by anormal expansion of CTG trinucleotide repeats located in the 3'-untranslated region of the DMPK gene. The clinical features of DM1 are multisystemic and highly variable, and the unstable nature of CTG expansion causes wide genotypic and phenotypic presentations. In this study, we described to our knowledge for the first time the molecular diagnosis of myotonic dystrophy type 1 patients in the Mexican population, applying a fluorescent PCR method in combination with capillary electrophoresis analysis of the amplified products. We identified expanded alleles in 45 out of 50 patients (90%) with clinical features of myotonic disease. Furthermore, genotyping of 400 healthy subjects revealed the presence of 25 different alleles, ranging in size from 5 to 34 repeats. The most frequent allele was 13 CTG repeats (38.87%) and the frequency for alleles over 18 CTG repeats was 6.7%. Molecular test is essential for DM1 diagnosis and distribution of the CTG repeat alleles present in the Mexican population are significantly different from those of other populations.
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PMID:Distribution of CTG repeats at the DMPK gene in myotonic dystrophy patients and healthy individuals from the Mexican population. 2063 51

DM1 (myotonic dystrophy type I) is a common form of muscular dystrophy that affects mainly adults. It is a disease that belongs to the group of defective RNA export diseases, since a major part of the pathogenic mechanism of the disease is the retention of the mutant transcripts in the cell nucleus. The presence of an expanded CUG trinucleotide repeat in the 3'-UTR (3'-untranslated region) of the DMPK (myotonic dystrophy protein kinase) gene causes the attraction of RNA-binding proteins by the nuclear-located mutant transcripts. As a result of the occupation of the RNA-binding proteins, there is defective mis-splicing of several cellular transcripts. This is believed to be a major pathogenic mechanism of the disease and any attempt to repair the activities of the RNA-binding proteins or target the mutant transcripts should be beneficial for the patients. Certain approaches have been described in the literature and they demonstrate progress in various directions. The purpose of the present review is to summarize the successful attempts to tackle the pathogenesis caused by nuclear retention of mutant transcripts in myotonic dystrophy and to discuss the possible gains from such approaches.
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PMID:Tackling the pathogenesis of RNA nuclear retention in myotonic dystrophy. 2069 Sep 4

Facioscapulohumeral muscular dystrophy (FSHD) is the third most common inherited muscular dystrophy with markedly clinical variability and complex genetic cause. Several reports pertaining to the Caucasian population have confirmed that there are 4qA and 4qB variants of the 4qter subtelomere, and FSHD is uniquely associated with the 4qA variant. However, few data relevant to the Chinese population have been published. In present paper, detailed clinical and genetic re-evaluations were performed in members of four special families who had been initially diagnosed as atypical or asymptomatic FSHD based only on the D4Z4 repeat length analysis. The FSHD-sized D4Z4 repeats in the probands from families 1, 2 and 3 were identified as 4qB variants. These patients were further confirmed as limb-girdle muscular dystrophy (LGMD2) or myotonic dystrophy (DM1) by molecular analyses. Specifically, we identified a 4qB variant on chromosome 10 in the healthy members of the fourth FSHD family with complex D4Z4 rearrangements of two exchanged repeat arrays. For the first time, we demonstrated in the Chinese population that D4Z4 contractions on the 4qB variant do not cause FSHD and 4qB variant on chromosome 10 might also represent intermediate structures in the transition from 4q to 10q. Furthermore, our results emphasize that D4Z4 repeat length analysis alone is not sufficient for the diagnosis of FSHD, especially when used as an exclusion criterion. This analysis should be accompanied by 4qA/4qB variant determination and integrated chromosome assignments, especially in patients with obscure and unclassified myopathies similar to atypical forms of FSHD.
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PMID:Distinguishing the 4qA and 4qB variants is essential for the diagnosis of facioscapulohumeral muscular dystrophy in the Chinese population. 2073 73


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