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)

Rigid spine syndrome (RSS) is clinically characterized by progressive limitation of flexion of the spine and contractures of other joints. We herein report a 27-year-old man with RSS, who underwent tracheotomy because of severe restrictive respiratory failure. He had limitation of neck flexion and proximal muscle weakness from early childhood and was diagnosed as having muscular dystrophy at 16 years old. He was suffered from dyspnea and his first tracheotomy was performed at 24 years old. Two years later, the second tracheotomy was done because his respiratory failure was aggravated. He had limitation of spine flexion, scoliosis, but no limited range of elbow and wrist joints movement except mild contracture of ankle joints. Serum CK level was elevated to 590 IU/L. Repeated ECG examinations showed negative T wave but no conduction block. In his family, his parents and brother had neither similar clinical symptoms nor heart block. Chest X-ray study showed elevated diaphragm and enlarged heart shadow (CTR = 65%). Percent VC and FEV1 in sitting position were 14.6% and 100%, respectively. Arterial blood gas analysis showed PaO2 of 34.2 mmHg and PaCO2 of 77.2 mmHg. The density of paraspinal muscle in CT scan was severely decreased. Needle EMG showed myogenic change. Muscle biopsy from left biceps brachii showed myopathic change with mild type 2 fiber grouping. After the second tracheotomy, he was on a respiratory during sleep but mostly off in the daytime. His clinical features are different from Emery-Dreifuss muscular dystrophy because he had no heart conduction block and no family history, but progressive respiratory failure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A case of rigid spine syndrome associated with severe respiratory failure]. 176 65

The original Virginia family with X-linked muscular dystrophy with early contractures and cardiomyopathy (Emery-Dreifuss type) has been reinvestigated 25 years later. The findings confirm that a cardiomyopathy, presenting most often as atrioventricular block, is a significant feature of the disease, which is characterized by the triad of: 1) slowly progressive muscle wasting and weakness with a humero-peroneal distribution in the early stages; 2) early contractures of the elbows, Achilles tendons, and post-cervical muscles; and 3) a cardiomyopathy usually presenting as heart block (some female carriers may also develop heart block). Other reported families with X-linked Emery-Dreifuss muscular dystrophy as well as a rare autosomal variant are reviewed, and differentiation from scapulo-peroneal muscular dystrophy and the rigid spine syndrome is discussed.
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PMID:X-linked muscular dystrophy with early contractures and cardiomyopathy (Emery-Dreifuss type). 331 95

We report on a patient with myotonic muscular dystrophy in whom mitral valve prolapse associated with prolonged PR interval and left anterior hemiblock was documented 3 years before any clinical evidence of myotonia, muscle weakness or wasting. One year after diagnosis had been established, he developed atrial flutter with 1:1 atrioventricular conduction, an arrhythmia that in addition to complete heart block and ventricular arrhythmias may account for the occurrence of syncope and sudden death in this group of patients.
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PMID:Unusual cardiac manifestations in a patient with myotonic muscular dystrophy. 372 33

While deficient exercise performance of sick children results from hypoactivity and detraining, it can also be caused by specific pathophysiological factors. These can affect one or more components of physical fitness. A low maximal aerobic power will result from a low maximal stroke volume, as in aortic stenosis or cardiomyopathy; a low maximal heart rate, as in congenital complete heart block or intake of beta-blockers; a low O2 content of the arterial blood, as in anemia or advanced cystic fibrosis; and a high O2 content of mixed-venous blood, as in muscle atrophy or severe malnutrition. A high O2 cost of locomotion, as in advanced obesity or cerebral palsy, will cause the patient to exert at a high percentage of his maximal aerobic power and thus fatigue easily. A subnormal muscle strength, as in progressive muscular dystrophy or juvenile rheumatoid arthritis, is sometimes the primary factor that limits the walking ability or other daily functions. Recent data suggest that local muscle endurance, as assessed by the Wingate anaerobic test, is particularly deficient in some neuromuscular diseases. Examples are muscular dystrophies and spastic cerebral palsy. The ratio of peak anaerobic power to peak aerobic power seems lower in such patients than in able-bodied controls.
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PMID:Pathophysiological factors which limit the exercise capacity of the sick child. 372 7

The muscular dystrophies are a clinically and genetically heterogeneous group of skeletal muscle-wasting diseases that differ widely in their frequency and pattern of cardiac involvement. Myocardial disease manifesting predominantly as cardiomyopathy and congestive heart failure is characteristic of Duchenne and Becker muscular dystrophies and X-linked dilated cardiomyopathy, whereas conduction system abnormalities that cause heart block, arrhythmias, and sudden death are more commonly seen in limb-girdle type 1B, myotonic, and Emery-Dreifuss muscular dystrophies. Primary defects in the mechanical stabilization of the plasma membrane and signal transduction may underlie these two groups of muscular dystrophies. The identification of several new disease genes has yielded additional insights into the pathophysiology of muscular dystrophy. Molecular genetic and biochemical analyses of patient samples now permit accurate diagnosis and genotype-phenotype correlations. Ultimately, this knowledge will provide the foundation for etiology-specific gene therapy.
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PMID:Dystrophies and heart disease. 924 91

Myotonic dystrophy (DM) is the most common form of muscular dystrophy and is caused by expansion of a CTG trinucleotide repeat on human chromosome 19. Patients with DM develop atrioventricular conduction disturbances, the principal cardiac manifestation of this disease. The etiology of the pathophysiological changes observed in DM has yet to be resolved. Haploinsufficiency of myotonic dystrophy protein kinase (DMPK), DM locus-associated homeodomain protein (DMAHP) and/or titration of RNA-binding proteins by expanded CUG sequences have been hypothesized to underlie the multi-system defects observed in DM. Using an in vivo murine electrophysiology study, we show that cardiac conduction is exquisitely sensitive to DMPK gene dosage. DMPK-/- mice develop cardiac conduction defects which include first-, second-, and third-degree atrioventricular (A-V) block. Our results demonstrate that the A-V node and the His-Purkinje regions of the conduction system are specifically compromised by DMPK loss. Importantly, DMPK+/- mice develop first-degree heart block, a conduction defect strikingly similar to that observed in DM patients. These results demonstrate that DMPK dosage is a critical element modulating cardiac conduction integrity and conclusively link haploinsufficiency of DMPK with cardiac disease in myotonic dystrophy.
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PMID:DMPK dosage alterations result in atrioventricular conduction abnormalities in a mouse myotonic dystrophy model. 1002 68

DMPK is a serine/threonine kinase implicated in the human disease myotonic muscular dystrophy (DM). Skeletal muscle Na channels exhibit late reopenings in Dmpk-deficient mice and peak current density is reduced, implicating DMPK in regulation of membrane excitability. Since complete heart block and sudden cardiac death occur in the disease, we tested the hypothesis that cardiac Na channels also exhibit abnormal gating in Dmpk-deficient mice. We made whole cell and cell-attached patch clamp recordings of ventricular cardiomyocytes enzymatically isolated from wild-type, Dmpk+/-, and Dmpk-/- mice. Recordings from membrane patches containing one or a few Na channels revealed multiple Na channel reopenings occurring after the macroscopic Na current had subsided in both Dmpk+/- and Dmpk-/- muscle, but only rare reopenings in wild-type muscle (>3-fold difference, P < 0.05). This resulted in a plateau of non-inactivating Na current in Dmpk-deficient muscle. The magnitude of this plateau current was independent on the magnitude of the test potential from -40 to 0 mV and was also independent of gene dose. Macroscopic Na current density was similar in wild-type and Dmpk-deficient muscle, as was steady-state Na channel gating. Decay of macroscopic currents was slowed in Dmpk-/- muscle, but not in Dmpk+/- or wild-type muscle. Entry into, and recovery from, inactivation were similar at multiple test potentials in wild-type and Dmpk-deficient muscle. Resting membrane potential was depolarized, and action potential duration was significantly prolonged in Dmpk-deficient muscle. Thus in cardiac muscle, Dmpk deficiency results in multiple late reopenings of Na channels similar to those seen in Dmpk-deficient skeletal muscle. This is reflected in a plateau of non-inactivating macroscopic Na current and prolongation of cardiac action potentials.
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PMID:Abnormal Na channel gating in murine cardiac myocytes deficient in myotonic dystrophy protein kinase. 1245 5