18. Molecular Genetic Tools

Methods for Analyzing DNA

Open Question
Using the genomic libraries in Problem 4, you wish to clone the human gene encoding myostatin, which is expressed only in muscle cells.How frequently will a clone representing myostatin be found in the cDNA library made from muscle?
Open Question
Using the genomic libraries in Problem 4, you wish to clone the human gene encoding myostatin, which is expressed only in muscle cells.How frequently will a clone representing myostatin be found in the cDNA library made from brain?
Open Question
A victim of murder is found to have scrapings containing skin cells under several of her fingernails. Genetic analysis confirms that the DNA isolated from these cells came from the same individual and does not match the DNA of the victim. The results shown below are for six CODIS STR markers from the crime scene DNA (from under the victim's fingernails and presumed to be the murderer's), and from three suspects (A, B, and C) who have been detained for questioning about the murder.Is there a failure to exclude any of the suspects? Explain.
Open Question
A victim of murder is found to have scrapings containing skin cells under several of her fingernails. Genetic analysis confirms that the DNA isolated from these cells came from the same individual and does not match the DNA of the victim. The results shown below are for six CODIS STR markers from the crime scene DNA (from under the victim's fingernails and presumed to be the murderer's), and from three suspects (A, B, and C) who have been detained for questioning about the murder.Do the STR results exclude any of the three suspects? Explain.
Open Question
The results shown are from a DNA test for four genes used in a paternity identification case. DNA for the mother (M) and her child (C) are shown along with DNA from two possible fathers, F1 and F2.What can you conclude based on the DNA results available?
Open Question
The results shown are from a DNA test for four genes used in a paternity identification case. DNA for the mother (M) and her child (C) are shown along with DNA from two possible fathers, F1 and F2.Based on the exclusion principle, is either man excluded as the possible father? Explain.
Open Question
The results shown are from a DNA test for four genes used in a paternity identification case. DNA for the mother (M) and her child (C) are shown along with DNA from two possible fathers, F1 and F2.In the 'C' column, label the DNA bands contributed by the mother with 'M' and the DNA bands contributed by the father with 'F.'
Open Question
As genetic testing becomes widespread, medical records will contain the results of such testing. Who should have access to this information? Should employers, potential employers, or insurance companies be allowed to have this information? Would you favor or oppose having the government establish and maintain a central database containing the results of individuals' genome scans?
Open 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.
Open Question
Might it make sense someday to sequence every newborn's genome at the time of birth? What are the potential advantages and concerns of this approach?
Open 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.
Open Question
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?

DNA sequencing of a breast tumor reveals mutations in the BRCA1 gene.
Open Question
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?

ASO testing determines that an individual is a carrier for the mutant β-globin allele (βˢ) found in sickle-cell anemia.
Open Question
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?

Individual sequencing (personal genomics) identifies a mutation associated with Alzheimer's disease.
Open Question
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?

An adult diagnosed with Asperger syndrome (AS) has a genetic test that reveals a SNP in the GABRB3 gene that is significantly more common in people with AS than the general population.