Genetic Variations

Research during the 1930s led to the discovery of an important region in human chromosomes known as the telomere. The enzyme telomerase enables the replacement of the telomere region in a chromosome. Assure Jane Marlow that gene testing or DNA testing has become a widely used tool to identify many disorders and can be a valuable tool for diagnosing conditions early on so that appropriate steps can be taken to prevent further risks of developing diseases. Ensure you cover the following areas:

What is the function of telomeres with regard to cell division?

If a patient has an abnormality in telomerase activity, how might this contribute to cancer?

Additionally, answer the following questions:

Duchenne muscular dystrophy (DMD) is an X-linked disease for which prenatal diagnostic testing can be performed. Has prenatal genetic testing increased the detection rate of this disease, compared to prior diagnostic methods? If so, how? If not, why? In case the fetus is diagnosed with DMD and parents decide to terminate the pregnancy, are there chances that the next child will also be a carrier of the disease?

Jane Hill's husband, Charlie Marlow, has hemophilia A when he marries Hill, who does not have the disorder. Jane's parents also do not have hemophilia, but her brother Steve Hill does. What is the probability that the Marlows' son will have the disorder? What is the probability that their daughter will have hemophilia? Are there chances that their daughter will be a carrier of this disorder?