Quantitative Traits: Risk assessment

by Georgina Cornwall, PhD

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    Those two ways of measuring and assessing relative risk are something that you should keep in mind and be able to calculate lambdas. If we are looking to now calculate the risk of a quantitative trait, we have to use a little bit different of a study. Generally, correlation and heritability studies will be used to determine risk of these sorts of factors. First of all, correlation studies. You've all probably seen a graph very much like this, the scatter plot and the average slope is determined by Y. When we’re considering genetics, we call this the coefficient of correlation or r. I mean I guess we do it any time we’re graphing it. The coefficient of correlation is a measure of similarities among relatives. We could have a positive correlation where there is a similarity or a negative correlation by a straight line or downward slope where we do not see perhaps any correlation between family members. Heritability studies are the other measure we can do, we call heritability H2 or H squared, how much variation in a phenotypic trait is actually attributable to genetic variation among individuals as opposed to environmental regulation. How do you think we calculate this one? Well, let’s take a quick look. If we have heritability equaling one then all, so 100% of the variation is attributable to genetics or we can have zero where none of it is attributable to genetics or anywhere in between. We can use twin studies to offer insight. We have monozygotic, dizygotic twins. I’m sure you are very familiar with the difference between identical and fraternal twins but here is just a reminder. But the point here is that identical twins share 100% of their genetic information. I have in parenthesis here theoretically because as you know,...

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    The lecture Quantitative Traits: Risk assessment by Georgina Cornwall, PhD is from the course Multifactorial Inheritance.

    Author of lecture Quantitative Traits: Risk assessment

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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