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Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 6 - Genetic Analysis and Mapping in Bacteria and BacteriophagesProblem A.3
Chapter 6, Problem A.3

A couple comes into your genetic counseling practice with a question about the chance a future child of theirs might have a genetic disease. Three or four men in the woman's family, including her father, had a condition that might be genetic. Although her father is still alive, she has had little contact with him for much of her life and cannot describe or name the condition. Her partner is a healthy man whose family has no history indicating the presence of a genetic condition. To provide more information about this possible genetic condition for the couple, what is the first step you recommend?

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Begin by gathering detailed information about the genetic condition in the woman's family. This includes identifying affected individuals, their relationship to the woman, and any medical records or diagnoses available for her father or other family members.
Determine the inheritance pattern of the condition. Based on the information provided, assess whether the condition might follow an autosomal dominant, autosomal recessive, X-linked, or mitochondrial inheritance pattern. This can be inferred from the number of affected males and the family structure.
Recommend genetic testing for the woman's father, as he is a living affected individual. Testing can help identify the specific genetic mutation or condition, which is crucial for understanding the risk to future offspring.
If the genetic condition is identified in the father, consider testing the woman to determine whether she is a carrier or affected by the same genetic mutation. This step is essential for assessing her risk of passing the condition to her children.
Once the genetic information is obtained, calculate the probability of the couple's future child inheriting the condition based on the inheritance pattern and the woman's carrier or affected status. Provide counseling to the couple about their reproductive options, including prenatal testing or assisted reproductive technologies if necessary.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Family History Assessment

Understanding the family history is crucial in genetic counseling, as it helps identify potential hereditary conditions. By gathering detailed information about the health of relatives, particularly those with known genetic disorders, counselors can assess the risk of passing on genetic diseases to future children. This step often involves constructing a pedigree to visualize inheritance patterns.
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Autosomal Dominant and Recessive Inheritance

Genetic conditions can be inherited in various patterns, with autosomal dominant and recessive being the most common. In autosomal dominant inheritance, only one copy of the mutated gene from an affected parent can cause the condition, while in autosomal recessive inheritance, two copies (one from each parent) are necessary. Understanding these patterns helps predict the likelihood of a child inheriting a genetic condition.
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Genetic Testing Options

Genetic testing can provide valuable information about the risk of inherited conditions. In this scenario, testing the woman for known mutations associated with her family's condition, if identified, can clarify her risk of being a carrier. Additionally, carrier screening for her partner may also be recommended to assess the combined risk for their future children.
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Related Practice
Textbook Question

Go online to the Online Mendelian Inheritance of Man (OMIM) website. Look up the following genetic conditions and answer the questions posed about them.

Go to the 'Molecular Genetics' section and describe the most common mutation of the CF gene.

Textbook Question

Go online to the Online Mendelian Inheritance of Man (OMIM) website. Look up the following genetic conditions and answer the questions posed about them.

Look up cystic fibrosis (CF), OMIM 602421, and give the gene name and abbreviation and the chromosome location of the gene.

Textbook Question

Conjugation between an Hfr cell and an F⁻ cell does not usually result in conversion of exconjugants to the donor state. Occasionally, however, the result of this conjugation is two Hfr cells. Explain how this occurs.

Textbook Question
Bacteria transfer genes by conjugation, transduction, and transformation. Compare and contrast these mechanisms. In your answer, identify which if any processes involve homologous recombination and which if any do not.
Textbook Question

Explain the importance of the following features in conjugating donor bacteria:

the origin of transfer

Textbook Question

Explain the importance of the following features in conjugating donor bacteria:

the conjugation pilus