Exam 15: Gene Mutation and Molecular Medicine

Refer to the figure. In Huntington's disease (HD) triplicate repeats of CAG in the huntingtin gene (HTT) cause a neurodegenerative disease that has a typical age of onset of between 30 and 50 years.A 38-year-old father has been diagnosed with HD.He and his wife are concerned that their four children may develop the disease, so they have the entire family undergo genetic testing.The HTT allele from each family member's DNA sample is amplified using PCR, and the products are then separated using gel electrophoresis.In the figure, the markers on the left side indicate how many triplicate repeats of CAG are in the HTT allele control samples.A person with >40 CAG repeats has a strong possibility of developing HD.When a parent has enough CAG repeats to cause HD, the disease is inherited in an autosomal dominant pattern.According to the results shown, which two of the children have a strong possibility of developing HD?

Gel electrophoresis is able to separate DNA fragments strictly by relative size assuming

Excess numbers of the CGG triplets in the FMR1 gene lead to clinical symptoms, including mental retardation, because _______, which in turn contributes to death of nerve cells.

A chromosomal mutation that results in a change of gene order on the same chromosome is a(n)

Which of the following nucleotide changes is a transversion?

In allele-specific oligonucleotide hybridization assays, the probe

Which therapeutic scenario does not illustrate the concept of treating a genetic disease by modifying its full phenotype?

Which method of treating disease would most likely make use of adeno-associated virus?

A child complains of dizziness and sporadic pain in his joints.Because sickle-cell anemia runs in the family, his doctor tests for the _______ of the disorder via a blood smear, which reveals a low red blood cell count and fragmented red blood cells.To confirm the _______ of the disorder, the doctor orders a DNA sequencing test of hemoglobin.

Individuals with maple syrup urine disease have urine with a sweet odor due to an enzyme defect that leads to a buildup of leucine and other branched-chain amino acids in their tissues.Such individuals are usually treated with a diet that is low in these amino acids.This form of treatment is an example of

The phenomenon of expanding triplet repeats plays a role in

Which statement comparing ex vivo and in vivo gene therapies is true?

Which disease is due to a mutation in a gene whose product transports gases?

A child is diagnosed with a novel metabolic disease.In an interview with the parents, the clinician learns that the symptoms exhibited by the child are commonly found within the extended family.The clinician is able to obtain blood samples from all of the afflicted members of the extended family, as well as multiple unafflicted members.Which technique would be most appropriate to identify the gene of interest?

Refer to the following image. Given the codon UCA in the first exon of a gene, which change is most likely to result in a nonsense mutation?

Refer to the figure. The figure shows a fragment of DNA that has been cut into two fragments by restriction enzyme EcoRI, and into three fragments by restriction enzyme HindIII.Lane A shows the results of digestion with EcoRI, Lane B shows the results of digestion with HindIII, and Lane C shows DNA of known lengths, specifically 1, 2, 5, and 10 kilobases (1 kilobase = 1,000 bp).How long is the original fragment of DNA?

Benzopyrene, a component of cigarette smoke, can induce DNA mutations by

Human hemoglobin contains _______ alpha chain(s) and _______ beta chain(s).

If a disease is due to a completely dominant mutation, the DNA of individuals that hybridize both normal and disease probes in allele-specific oligonucleotide hybridization should _______.If a disease is due to a completely recessive mutation, the DNA samples of individuals that hybridize both normal and disease probes in this test should _______.

Individuals with PKU have _______ levels of phenylalanine before birth and _______ levels of phenylalanine shortly after birth if provided normal breast milk.