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16 Cards in this Set
- Front
- Back
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what is a polygenic trait?
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multiple genes working together to exhibit an effect on a trait
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what does multifactorial mean?
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a polygenetic trait that has environmental factors that contribute to its expression.
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what is the additive polygenetic model?
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a simple model that represents polygenetic inheritance in the form of a bell curve without taking environmental factors into consideration.
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what is the threshold model?
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a model that takes genetic and environmental factors into play and sets a risk threshold for the development of a disease. you have it or you dont
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What causes a threshold to change?
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if you change the population you are looking at or a new environment exists
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is pyloric stenosis more prevalent in males or females?
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4 times more likely to occur in males
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what is a proband?
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the first individual in a family to exhibit a disease
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can you calculate the occurence risk of a multifactorial disease?
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no. we have little to no idea what genes are playing a part in the disease and how to calculate risk from all of the variables
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how do we determine the recurrence risk of multifactorial diseases?
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observed data from the given population
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what are the two factors considered when predicting the recurrence risk.
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the degree of relatedness
the severity of the disease in the proband |
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which has a faster rate of decline in recurrence risk as the degree of relationship increases, single gene traits or polygenetic traits?
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Polygenetic traits.
so many factors have to accumulate to create the disease. it is unlikely that those factors would be present in more distantly related individuals |
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what increases the recurrence risk for those closely related to the proband?
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the severity of the disease in the proband
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what are the 4 criteria used to define multifactorial inheritance?
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1. recurrence risk increases when more than one sibling is affected by the disorder
2. risk increases if the proband is of the less commonly affected sex 3. risk increases with the severity of disease in the proband 4. risk drastically decreases as the degree of relatedness increases |
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what does concordance mean?
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if both twins share a trait
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what is heritability?
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the amount of genetic influence for a given trait
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what is the equation for estimating heritability?
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h= 2(Cmz - Cdz)
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