Term
| What is the cause of Emery-Dreifuss Syndrome? |
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Definition
Mutations in genes that code for proteins involved in the nuclear membrane (some lamina, some inner membrane)
Most are X-linked recessive, some are autosomal dominant |
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Term
| What are the manifestations of Emery-Dreifuss Syndrome? |
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Definition
1. Slowly progressive muscle wasting
2. Contractures of elbows, neck, and Achilles
3. Abnormal heart rhythms, heart block, and cardiomyopathy |
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Term
| Define genetic anticipation |
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Definition
A disease in which symptoms get worse with each generation
(associated with myotonic dystrophy) |
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Term
| What is the most common muscular dystrophy in adults and what is its cause? |
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Definition
Myotonic Dystrophy
Caused by mutations in either DM1 or DM2 gene (CTG repeat) |
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Term
| What are the symptoms of DM1? |
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Definition
Myotonia - delayed relaxation
Myopathy - weakness of facial and limb muscles
Conduction problems of the heart
Cataracts
Daytime sleepiness
GI symptoms
low intelligence |
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Term
| Which of the myotonic dystrophies is typically more severe? |
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Definition
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Term
| Describe the gain-of-function effect |
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Definition
| CUG repeats in mRNA leads to abnormal splicing of the mRNA. This abnormal splicing can lead to unintended proteins with different function |
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Term
| Mutations in the dystrophin gene can cause what to diseases? |
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Definition
Duchenne's Muscular Dystrophy
Becker's Muscular Dystrophy |
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Term
| What are the symptoms of Duchenne's |
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Definition
| Myopathy, muscle weakness, cardiomyopathy, mental retardation, deterioration of pulmonary function (either this or heart failure usually lead to death) |
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Term
| What are the symptoms of BMD? |
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Definition
| Similar to DMD, but not as severe, and mental retardation is not typically a symptom |
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Term
| What role does Dystrophin associated protein complexes play in maintaining cell life? |
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Definition
1. Stabilization of the cell membrane under mechanical stress
2. Signal transduction |
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Term
| explain how the reading frame plays a role in dystrophin gene mutations |
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Definition
In BMD there is an in frame deletion that creates a smaller but still functional protein (deletion is a multiple of 3, so it deletes amino acids but still largely functional)
In DMD there is an out of frame (1 or 2 nucleotides) deletion that alter the mRNA completely and shift the reading frame leading to an early stop that leads to truncated, non functional protein |
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Term
| What are the symptoms of FSH |
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Definition
| Genetic anticipation, weakness in face and shoulders, loss of high frequency hearing and retinal telangiectasias |
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Term
| What are the symptoms of Limb girdle muscular dystrophy |
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Definition
| Weakness and wasting of muscles around the shoulder and hips |
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