A Genetics Student Recently Learned of the Connection Between Telomerase

question 70

Multiple Choice

A genetics student recently learned of the connection between telomerase and cancer. Curious as to whether he is at risk for developing cancer, he sneaks into a lab at night to analyze his DNA. He isolates DNA from his skin cells and applies PCR using primers specific to the telomerase gene. He runs a gel on his PCR reaction and sees that he has a PCR product on the gel. He is terrified because he knows this means he has the telomerase gene in his skin cells and thinks he will develop skin cancer. He takes his findings to his genetics professor. What does she tell him (besides he shouldn't be sneaking into a lab!) ?

• A) The telomerase gene should not be present in somatic cells; thus, he is at an increased risk of developing skin cancer and should take the results to his physician.
• B) His results are normal because the telomerase gene should be present in all cells, including somatic cells. However, its expression should only be found in stem cells and germ cells. He should have looked at the expression levels of the gene, not the presence of the gene itself (and he should study more!).
• C) His results are inconclusive because they cannot determine if the telomerase gene he amplified has a mutation in its coding sequence, which is what leads to cancer.
• D) Telomerase mutations that result in cancer behave in a dominant manner. Therefore, rather than going through the effort of a genetic analysis, the student should have constructed a family pedigree to determine if members of his family had skin cancer, which could then determine his risk.
• E) He should not be concerned about his cancer risk because transcriptionally active telomerase should be present in somatic cells to maintain the length of the chromosomes and thus prevent cancer.