18 Questions
What is the overall population risk of carrying a fetus with a neural tube defect (NTD) in the United States?
1 in 1,000 (0.1 percent)
How does the number of affected family members affect the empiric risk?
The more affected family members, the higher the empiric risk.
What is the difference between empiric risk and heritability?
Empiric risk includes both genetic and nongenetic influences, while heritability focuses on the genetic component of the variation in a trait.
What is the increased risk of recurrence if a sibling has an NTD?
3 percent
Why is heritability important in understanding the variation of a trait?
It estimates the degree of variation in a trait due to genetics.
Why is the closeness of relationship between individuals important in predicting the likelihood of a trait?
The closer the relationship, the greater the probability that the second individual has the trait, because they share more genes.
What is meant by a heritability of 1.0 for a trait?
It means that the variability of the trait is completely due to gene action, with no environmental influence.
Why is heritability not 1.0 for most traits?
It is because the variability of most traits is due to differences among both genes and environmental components.
How do researchers estimate heritability?
One way is to compare the proportion of people sharing a trait to the proportion predicted to share the trait, based on their blood relationships.
What does a high heritability of a trait indicate?
It indicates that a large proportion of the variation in the trait is due to genetic differences.
How is the heritability of a trait like height calculated?
It is calculated by dividing the observed phenotypic variation by the expected phenotypic variation if environment had no influence.
What does the heritability of a trait like height reflect?
It reflects the environmental influence of factors such as nutrition, in addition to genetic differences.
What is the primary distinction between single-gene and polygenic traits?
Single-gene traits are influenced by a single gene, whereas polygenic traits are influenced by multiple genes.
In the context of multifactorial traits, what is empiric risk?
Empiric risk is the probability that an individual will develop a certain trait or condition based on their family history.
How do studies on adopted individuals and twins contribute to our understanding of multifactorial traits?
These studies help scientists distinguish between genetic and environmental influences on trait development.
What can a genome-wide association study (GWAS) reveal about multifactorial traits?
A GWAS can identify specific genetic variants associated with a trait, which can help determine its heritability.
How is heritability defined in the context of multifactorial traits?
Heritability is the proportion of variation in a trait that can be attributed to genetic factors.
What is an example of a multifactorial trait influenced by both genetic and environmental factors?
Athletic ability is a multifactorial trait influenced by multiple genes and environmental factors.
Test your understanding of heritability, a concept in genetics that measures the contribution of genetic variation to the variation of a trait. Learn how to calculate heritability and its significance in determining the expression of traits in a population.
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