Podcast
Questions and Answers
What is the primary difference between muscular dystrophies and congenital myopathies?
What is the typical effect of myopathy on skeletal muscles?
What is the characteristic feature of hereditary myopathies?
What is the genetic basis of Duchenne and Becker muscular dystrophy?
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How many genes are responsible for the development of muscular dystrophies?
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What is the characteristic of muscle weakness in Polymyositis?
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Which type of myopathies results from defects in cellular energy metabolism?
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What is the characteristic skin symptom of Dermatomyositis?
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What is the primary cause of Mitochondrial myopathies?
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What is the age range in which Dermatomyositis most commonly develops?
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Study Notes
Myopathy Definition
- Myopathy is a muscle disease unrelated to innervation or neuromuscular junction disorders, with various etiologies.
General Characteristics
- Most types of myopathy result in weakening and atrophy of skeletal muscles, specifically proximal muscles (thigh and shoulder muscles).
Hereditary Myopathies
- Hereditary myopathies are inherited disorders primarily affecting skeletal muscle tissue, caused by mutations in genes encoding proteins crucial for muscle structure and function.
Muscular Dystrophies
- Muscular dystrophies are a heterogeneous group of hereditary illnesses affecting both children and adults, with at least 30 different genes responsible for the disease development.
- The most common muscular dystrophies are Duchenne and Becker muscular dystrophy, resulting from a genetic defect on the X chromosome.
- These diseases are characterized by muscle wasting and weakness, with elevated levels of creatine phosphokinase (CPK).
Congenital Myopathies
- Congenital myopathies are present at birth, with no necrotic or degenerative changes, and CPK levels are often normal.
- This group includes conditions such as nemaline myopathy, central core disease, X-linked myotubular myopathy, and centronuclear myopathy.
Metabolic Myopathies
- Metabolic myopathies comprise a diverse group of disorders arising from defects in cellular energy metabolism, including the breakdown of fatty acids and carbohydrates to generate ATP.
- Reduction of ATP is a key feature of these disorders.
Mitochondrial Myopathies
- Mitochondrial myopathies result from primary dysfunction of the mitochondrial respiratory chain, causing muscle disease.
- These disorders have genetic etiologies and can frequently present with multi-system dysfunction.
Genetic Defects
- Genetic defects in calcium, sodium, potassium, and chloride channels in skeletal muscles result in periodic paralyses and nondystrophic myotonias.
- This group of diseases includes myotonia congenita, paramyotonia congenita, hyper and hypokalemic periodic paralysis, and potassium-aggravated myotonia.
Idiopathic Inflammatory Myopathies
- Polymyositis (PM) causes muscle aches, cramping, and tenderness, with severe muscle weakness that may fluctuate over weeks to months.
- Dermatomyositis (DM) is characterized by a skin rash, in addition to muscle symptoms of PM, and often affects children between the ages of 5 and 14 years.
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Description
Learn about the different types of myopathy, a muscle disease that affects skeletal muscles. Explore hereditary myopathies and their causes.
