Epistasis vs Polygenic Inheritance

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amolvaidya06
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Epistasis vs Polygenic Inheritance

Post by amolvaidya06 » Thu Apr 05, 2007 7:23 am

Could anyone please briefly explain the difference between epistasis and polygenic inheritance? My biology book makes these two seem fairly close to one another, as multiple genes affect the same phenotype. The only difference I can really tell between the two is that polygenic inheritance seems to be a cumulative phenomenon whereas epistasis affects the phenotype of a particular gene via a completely different mechanism (such as not producing pigments, making a mouse an albino regardless of whether it should have a black or brown coat).

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LilKim
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Post by LilKim » Thu Apr 05, 2007 3:27 pm

You definition of epistatis Vs. poygenetic inheritence is essentially correct.

Polygeneic inheritence involves many genes producing a phenotype.

Epistasis is another gene (in the pathway or in another pathway) that changes the phenotype regardless of the genotype.

Epistatis has always been one of those really difficult terms for me to understand... and at the moment i am at a loss for a good example. (but the example you gave about mouse coat colors is a good one)

Try this link... see if it helps http://en.wikipedia.org/wiki/Epistasis


but.. based on what you've said you seem to have a good grasp of what you're talking about


good luck!
- kim

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Post by Darby » Thu Apr 05, 2007 5:49 pm

It may help to think of ALL phenotypes as being essentially polygenic, with all sorts of "background processors" that usually work fine but which can affect multiple systems if they don't work.

For instance, an albino has a problem with the gene for a protein involved in a lot of pigment processing, so pigmentation is affected in several systems.

amolvaidya06
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Post by amolvaidya06 » Fri Apr 06, 2007 9:33 pm

Thank you both for your responses! This really helps clear thing up for me.

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