Textbook Question
What is CODIS? Describe the four most important features of genetic markers used in this system.
Ch. 15 - Recombinant DNA Technology and Its Applications
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
Chapter 15, Problem E.4
What is the statistical principle underlying genetic health risk assessment? Why are these assessments not predictive of disease occurrence?
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Understand that genetic health risk assessment is based on the principle of probability and statistics, which estimate the likelihood of developing a disease based on the presence of certain genetic variants in a population.
Recognize that these assessments use data from population studies, such as genome-wide association studies (GWAS), to calculate risk scores by comparing the frequency of genetic markers in affected versus unaffected individuals.
Note that the risk provided is a statistical probability, not a certainty, because it reflects increased or decreased chances rather than a definitive outcome for an individual.
Consider that genetic risk assessments do not account for environmental factors, lifestyle, gene-gene interactions, and epigenetic modifications, all of which can influence whether a disease actually develops.
Conclude that because of the complex interplay between genes and other factors, genetic health risk assessments are useful for estimating risk but cannot predict with certainty if or when a disease will occur.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Statistical Probability in Genetic Risk Assessment
Genetic health risk assessments use statistical probability to estimate the likelihood that an individual will develop a certain disease based on genetic variants. These probabilities are derived from population studies and reflect risk, not certainty, indicating how often a genetic variant is associated with disease occurrence.
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Multifactorial Nature of Disease
Most common diseases result from complex interactions between multiple genes and environmental factors. Because genetic variants are only one part of this interplay, genetic risk assessments cannot definitively predict disease but rather indicate increased or decreased risk.
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Penetrance and Expressivity
Penetrance refers to the proportion of individuals with a particular genetic variant who actually express the associated trait or disease, while expressivity describes the variability in symptoms. Incomplete penetrance and variable expressivity limit the predictive power of genetic risk assessments.
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Related Practice
Textbook Question
Compare and contrast the terms Paternity Index (PI) and Combined Paternity Index (CPI). How does each contribute to paternity determination?
Textbook Question
What is the exclusion principle? How is it used in forensic genetic analysis and in paternity determination?
Textbook Question
Explain the meaning of 'identity by descent' in the context of identifying genealogical relationship between individuals. In these analyses, why are segments of chromosomes (haplotypes) rather than individual STRs used to identify genetic relationships?
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Textbook Question
Figure E.1 illustrates the results of an electrophoretic analysis of 13 CODIS STR markers on a DNA sample and identifies the alleles for each gene. Table E.2 lists the frequencies for alleles of three of the STRs shown in the figure. Use this information to calculate the frequency of the genotype for STR genes FGA, vWA, and D3S1358 given in Figure E.1.
Textbook Question
Additional STR allele frequency information can be added to improve the analysis in Problem 8. The frequency of D8S1179₁₂ = 0.12. The frequency of D16S539₁₈ = 0.08 and of D16S539₂₀ = 0.21. Lastly, D18S51₁₉ = 0.13 and D18S51₂₀ = 0.10. Combine the allele frequency information for these three STR genes with the information used in Problem 8 to calculate the frequency of the genotype for six of the STR genes.