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Muscle 2
8/29/11 Second Lecture
14
Medical
Graduate
08/30/2011

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Cards

Term
What is the cause of Emery-Dreifuss Syndrome?
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
Term
What are the manifestations of Emery-Dreifuss Syndrome?
Definition
1. Slowly progressive muscle wasting
2. Contractures of elbows, neck, and Achilles
3. Abnormal heart rhythms, heart block, and cardiomyopathy
Term
Define genetic anticipation
Definition
A disease in which symptoms get worse with each generation

(associated with myotonic dystrophy)
Term
What is the most common muscular dystrophy in adults and what is its cause?
Definition
Myotonic Dystrophy

Caused by mutations in either DM1 or DM2 gene (CTG repeat)
Term
What are the symptoms of DM1?
Definition
Myotonia - delayed relaxation
Myopathy - weakness of facial and limb muscles
Conduction problems of the heart
Cataracts
Daytime sleepiness
GI symptoms
low intelligence
Term
Which of the myotonic dystrophies is typically more severe?
Definition
DM1
Term
Describe the gain-of-function effect
Definition
CUG repeats in mRNA leads to abnormal splicing of the mRNA. This abnormal splicing can lead to unintended proteins with different function
Term
Mutations in the dystrophin gene can cause what to diseases?
Definition
Duchenne's Muscular Dystrophy

Becker's Muscular Dystrophy
Term
What are the symptoms of Duchenne's
Definition
Myopathy, muscle weakness, cardiomyopathy, mental retardation, deterioration of pulmonary function (either this or heart failure usually lead to death)
Term
What are the symptoms of BMD?
Definition
Similar to DMD, but not as severe, and mental retardation is not typically a symptom
Term
What role does Dystrophin associated protein complexes play in maintaining cell life?
Definition
1. Stabilization of the cell membrane under mechanical stress

2. Signal transduction
Term
explain how the reading frame plays a role in dystrophin gene mutations
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
Term
What are the symptoms of FSH
Definition
Genetic anticipation, weakness in face and shoulders, loss of high frequency hearing and retinal telangiectasias
Term
What are the symptoms of Limb girdle muscular dystrophy
Definition
Weakness and wasting of muscles around the shoulder and hips
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