Reduced penetrance vs. multifactorial?

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Reduced penetrance vs. multifactorial?

Post by Grumbot » Mon Apr 04, 2011 4:23 pm

Can anybody explain to me how you would be able to distinguish between a disease caused by a single-gene trait with low penetrance and a multifactorial trait?

Let's say you were presented with a disease that appeared to run in families but didn't exhibit an obvious pattern of Mendelian inheritence, how would you distinguish between the cause being a single gene disorder with low penetrance, and the disease being multifactorial?

Where is the cut off point between describing something as a single gene disorder with reduced penetrance and a polygenic disorder? (i.e. is it still meaningful to describe a disease as autosomal dominant with 1% penetrance?)

I understand that to an extent these phenomena are two ends of the same spectrum and perhaps the definition you'd adopt would be whichever has the most practical application, but surely one must be more appropriate than the other, as it would have implications for the calculation of recurrence risks and for genetic councelling?

Any help in clarifying this issue for me would be greatly appreciated.


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Post by DRT23 » Wed Apr 06, 2011 10:34 am

Penetrance is used as a statistical tool to determine the risk of getting ill when you have a particular well-known mutation. So, I don't think it's vital to distinguish if a disorder has reduced penetrance or multifactorial trait. Of course, this information would be helpful to combat with disorders and more genomic research will lead us to have that level of knowladge one day.

But, for now, I don't know any definite cut off point for this purpose.

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