Certified Neuroscience Registered Nurse (CNRN) Practice Exam

If a person has one parent with Huntington's disease, what is the chance of that individual also inheriting the disease?

1. 25%

2. 50%

3. 75%

4. 100%

The correct answer is: 50%

A person with one parent who has Huntington's disease has a 50% chance of inheriting the disorder due to the autosomal dominant nature of the disease. In autosomal dominant inheritance, a single copy of the mutated gene is sufficient to cause the disorder. Each child of a parent with Huntington's disease has a 50% chance of inheriting the mutated gene responsible for the condition. This is because the affected parent can pass on either the mutated gene or a normal gene with equal probability. Therefore, if the individual inherits the mutated gene, they will develop Huntington's disease; if they inherit the normal gene, they will not. This understanding highlights the clear genetic transmission pattern of Huntington's disease, distinguishing it from other types of inheritance patterns that might exhibit different probabilities, such as autosomal recessive or X-linked traits.