Question

Genetic

Genetic Variations

Research during the 1930s led to the discovery of an importantregion in human chromosomes known as the telomere. The enzymetelomerase enables the replacement of the telomere region in achromosome. Assure Jane Marlow that gene testing or DNA testing hasbecome a widely used tool to identify many disorders and can be avaluable tool for diagnosing conditions early on so thatappropriate steps can be taken to prevent further risks ofdeveloping diseases. Addresss the following:

• What is the function of telomeres with regard to celldivision?
• If a patient has an abnormality in telomerase activity, howmight this contribute to cancer?

Duchenne muscular dystrophy (DMD) is an X-linked disease forwhich prenatal diagnostic testing can be performed.

• Has prenatal genetic testing increased the detection rate ofthis disease, compared to prior diagnostic methods?
• If so, how? If not, why?
• In case the fetus is diagnosed with DMD and parents decide toterminate the pregnancy, are there chances that the next child willalso be a carrier of the disease?

Jane Hill's husband, Charlie Marlow, has hemophilia A when hemarries Hill, who does not have the disorder. Jane's parents alsodo not have hemophilia, but her brother Steve Hill does.

• What is the probability that the Marlows' son will have thedisorder?
• What is the probability that their daughter will havehemophilia?
• Are there chances that their daughter will be a carrier of thisdisorder?