M. T. Tsuang and colleagues studied drug dependence in male twin pairs (M. T. Tsuang et al. 1996. American Journal of Medical Genetics 67:473–477). They found that 82 out of 313 monozygotic twin pairs were concordant for abuse of one or more illicit drugs, whereas 40 out of 243 dizygotic twin pairs were concordant for the same trait. Calculate the concordances for drug abuse in these monozygotic and dizygotic twins. On the basis of these data, what conclusion can you draw concerning the roles of genetic and environmental factors in drug abuse?

M. T. Tsuang and colleagues studied drug dependence in male twin pairs (M. T. Tsuang et al. 1996. American Journal of Medical Genetics 67:473–477). They found that 82 out of 313 monozygotic twin pairs were concordant for abuse of one or more illicit drugs, whereas 40 out of 243 dizygotic twin pairs were concordant for the same trait. Calculate the concordances for drug abuse in these monozygotic and dizygotic twins. On the basis of these data, what conclusion can you draw concerning the roles of genetic and environmental factors in drug abuse?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter18: Genetics Of Behavior

Section: Chapter Questions

Problem 14QP: A pedigree analysis was performed on the family of a man with schizophrenia. Based on the known...

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Many researchers have estimated the heritability of human traits by comparing the correlation coefficients of monozygotic and dizygotic twins (see pp. 731–732). One of the assumptions made in using this method is that monozygotic twin pairs experience environments that are no more similar to each other than those experienced by dizygotic twin pairs. How might this assumption be violated? Give some specific examples of how the environments of two monozygotic twins might be more similar than the environments of two dizygotic twins.
In one twin study investigating the genetics of addiction, 41% of monozygotic twins both exhibited substance dependence while 24% of dizygotic twins both exhibited substance dependence. Does this twin study suggest that there is or is not a genetic component to addiction? What evidence in model organisms supports a genetic component to addiction?
A pedigree analysis was performed on the family of a man with schizophrenia. Based on the known concordance statistics, would his MZ twin be at high risk for the disease? Would the twins risk decrease if he were raised in an environment different from that of his schizophrenic brother?
Why are monozygotic twins who are reared apart so useful in the calculation of heritability?
What is concordance? For a polygenic or multifactorial trait such as behavior, why are identical (monozygous) twins studied? What is the advantage of studying identical twins reared apart? What should be the concordance in identical twins raised apart if a trait is purely genetic with no environmental influence? What are some genetic conditions or chromosomal abnormalities that cause changes in behavior?For example, Huntington disease; Fragile X syndrome. What is schizophrenia and why is it considered multifactorial? What is autism? Major depression? Bipolar disorder? What is: the purpose of our immune system? Our first line of defense against infection? • What are some differences between our innate immune system, and our adaptive immune system? What is an antigen? An antibody? Which cells make antibodies? What is a memory B cell? How do vaccines work? Why must HLA be matched for a successful organ transplant? Why is it difficult to find a good match?
What does a heritability score tell us about HOW genes and environment interact in an individual to produce a trait?
Pairs of genetically related people were examined with regard to the rate at which they metabolize glucose. For 25 pairs of individuals that had each of the following relationships, correlation coefficients for glucose metabolism were determined: Mother-daughter: 0.36 Mother-granddaughter: 0.17e Sister-sister: 0.39 Sister-sister (fraternal twins): 0.40 Sister-sister (identical twins): 0.77 What is the average heritability for the rate of glucose metabolism in this group of females?
Why are monozygotic twins who are reared apart so useful in the calculation of heritability? What assumption is being made about their respective environment?
For each of the following relationships, correlation coefficients forheight were determined for 15 pairs of individuals:Father-daughter: 0.41Father-granddaughter: 0.18Sister-sister: 0.40Sister-sister (fraternal twins): 0.41Sister-sister (identical twins): 0.83What is the average heritability for height in this group?
For each of the following relationships, correlation coefficients forheight were determined for 15 pairs of individuals: Mother-daughter: 0.36Mother-granddaughter: 0.17Sister-sister: 0.39Sister-sister (fraternal twins): 0.40Sister-sister (identical twins): 0.77What is the average heritability for height in this group of females?
A characteristic has a narrow-sense heritability of 0.6. a. If the dominance variance (VD) increases and all other variance components remain the same, what will happen to narrow-sense heritability? Will it increase, decrease, or remain the same? Explain. b. What will happen to broad-sense heritability? Explain. c. If the environmental variance (VE) increases and all other variance components remain the same, what will happen to narrow-sense heritability? Explain.
A given autosomal locus has three possible alleles (A1, A2, and A3). Assuming that the numbers of individuals with the six possible genotypes are as follows, what would be the frequency of the A1 allele in the population? A1A1 = 30 A1A2 = 27 A2A2 = 12 A1A3 = 17 A2A3 = 10 A3A3 = 4 What would be the frequency of the A3A3 genotype? Assume the population is under Hardy-Weinberg equilibrium. A. 0.182 B. 0.27 C. 0.03 D. 0.317 E. 0.107 F. 0.09