Concept explainers
With regard to pedigree analysis, make a list of observations that distinguish recessive, dominant, and X-linked patterns of inheritance.
To review:
The difference between recessive, X-linked, and dominant patterns of inheritance in accordance with the Pedigree analysis.
Introduction:
Pedigree analysis is the method used to determine the inheritance of genetic disorders. It is an important tool for studying the inherited disorders in the generations. The pedigree chart helps to visualize the relations between the large extended families.
Explanation of Solution
Differentiation between X-linked, dominant, and recessivepatterns of inheritance, according to the pedigree analysis are shown below:
Recessive inheritance | X-linked inheritance | Dominant inheritance |
Affected offspring has unaffected parents. | Both, parents and offspring are affected. | Unaffected offspring have affected parents. |
It is associated with autosomal genes. | Based on the X-chromosome genes. | It associated with the gene on the autosome. |
Recessive traits affect females and males equally. | Traits skip generations to appear and males are more affected than females. Females are the main carriers of the disease. | Dominant traits affect both male and female offspring in each generation. Dominant X-linked is always passed on from father to daughter. |
Therefore, it can be concluded thatX linked disease affects males, while in dominant inheritance, the disease affects the daughter. In recessive inheritance, both, the males and females have an equal chance of disease inheritance.
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Chapter 25 Solutions
Genetics: Analysis and Principles
- In a testcross, the parent that is homozygous recessive for the genes being studied is called the testcross parent. The parent that has the dominant phenotype of the genes being studied is called the non-testcross parent.Which of the following is NOT a reason that a testcross is a useful technique when studying the inheritance of a trait? a. A testcross can determine if an individual with the dominant phenotype is homozygous or heterozygous. b. The relative frequencies of the different phenotypes among the testcross progeny can be used to map linked genes. c. Because the testcross parent can contribute only recessive alleles, the alleles contributed by the other parent will be expressed in the offspring of the testcross. d. The gametes produced by the testcross parent are determined from the testcross progeny.arrow_forwardA biotechnology company offers a direct-to-consumer test called the Carrier Status report that generates various calculations about an individual’s genetic risk for certain diseases. Write one paragraph that addresses the following two issues: Why would this be most useful for disorders following an autosomal recessive pattern of inheritance? Provide evidence from your textbook (e.g., Section 10.7, Inheritance Patterns in Humans). Explain how this information might be useful for people during their reproductive years.arrow_forwardDiscuss how polygenic inheritance makes possible manyvariations of a trait.arrow_forward
- Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you want to know the results of the cancer, heart disease, and TSD tests if you were Sarah and Adam? Is it their responsibility as potential parents to gather this type of information before they decide to have a child?arrow_forwardPedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you decide to have a child if the test results said that you carry the mutation for breast and ovarian cancer? The heart disease mutation? The TSD mutation? The heart disease and the mutant alleles?arrow_forwardPedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. If Sarah carries the mutant cancer allele and Adam carries the mutant heart disease allele, what is the chance that they would have a child who is free of both diseases? Are these good odds?arrow_forward
- Pedigree Analysis Is a Basic Method in Human Genetics Using the pedigree provided, answer the following questions. a. Is the proband male or female? b. Is the grandfather of the proband affected? c. How many siblings does the proband have, and where is he or she in the birth order?arrow_forwardA 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?arrow_forwardWhat is the pattern of inheritance? Please Provide a specific reason that justifies your selection of this pattern of inheritance as the correct one, and also explain why each of the other two alternatives are not correct. As part of your answer, you must include the phenotypic ratio, including the sex of the offspring, that you would expect to find in each of the three possible scenarios. Please specify whether this pattren of inheritance is (i) rare X-linked recessive, (ii) sex-influenced, or (iii) sex-limited.arrow_forward
- Discuss how genomic imprinting can be inferred from inheritance patterns in human pedigrees.arrow_forwardLook at the pedigree below and answer the following questions related to the human genetic trait depicted in this pedigree. 1. Indicate whether the pattern of inheritance associated with this human trait is most likely to be (i) rare X-linked recessive, (ii) sex-influenced, or (iii) sex-limited. You may assume that the gene is fully penetrant. Then, provide a specific reason that justifies your selection of this pattern of inheritance as the correct one, and also explain why each of the other two alternatives are not correct. As part of your answer, include the phenotypic ratio, including the sex of the offspring, that you would expect to find in each of the three possible scenarios.arrow_forwardDescribe the concept of the extended phenotype. Can you think of a trait that you consider to be your own that could perhaps be due to the genetics of another organism you’ve interacted with in your life?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning