mash
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It has been observed that missense mutations in the fibrillin-1 gene on chromosome 15 often produce more severe presentations of Marfan syndrome than do nonsense mutations in the same gene. Explain this .
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| mjl1717
Forum Hero
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I think the main point is that a missense mutation is when a new codon
specifies a different amino acid-it causes decrease in function and "Variable effects."
Compared to nonsense mutation which Stops translation prematurely producing too short a polypeptide. {The missense mutation appears more profound}
And can cause the variable expressivity and incomplete penetrance
for example:
cystic medial necrosis[elastic tissue fragmentation],"double barrel aorta".
tearing retrosternal chest pain, Eunuchoid proportions,arachnodactyly,
*dissecting aortic aneurysms, lens dislocations, etc.
{In so many words the protein fibrillin causes alters metabolism in their connective tissue} Hope this helps.
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| Malaysian
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A nonsense mutation may not be a bad thing all the time.Though agreed it abruptly stops translation.However assume if the nonsense mutation happened at the end of the last exons....meaning close to the terminal codon....in this case it may have some physiological function and so may be more efficient than a missense mutation
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