Activity Huntington’s disease and sickle cell anemia are both hereditary gene mutations. Huntington’s disease is eventually fatal because it causes a breakdown of the nervous tissue in the brain. Sickle cell anemia is a mutation that causes an alteration in the shape of red blood cells, which affect delivery of oxygen to the body. Review the images, and then answer the questions.
Part A
Based on the pattern of inheritance, do you think the mutated Huntington’s and sickle cell genes are dominant or recessive?
Part B
The first signs of Huntington’s disease often appear when a person is in his or her 30s and 40s, but it can appear later in life. The earliest symptoms are often subtle, such as mood changes. Do you think the subtle presence of symptoms plays a role in this harmful gene persisting in our population? Why or why not?
Part C
In about 90% of cases, Huntington’s disease is inherited. But in 10% of cases, there is no evidence that a parent has the disease. Why do you think this is the case?
Part D
For both conditions, explain how protein synthesis contributes to the symptoms of the disease.
Part E
Gene therapy—altering the genetic code to repair or replace damaged genes—is a promising field for genetic conditions such as sickle cell anemia and Huntington’s disease. List one scientific question for each condition that could help guide gene therapy research for those diseases.
Part F
Explain how these mutated genes contribute to genetic variation in our species.