Why is predictive testing for Huntington disease avoided for a 4-year-old child who has one grandparent with the disorder?

Question

Quizplus · Accepted Answer

The Huntington disease mutation has a high penetrance, which means that a person who inherits the mutation will eventually express the disease. It also means that if a person is negative for this mutation, he or she will never develop this disease. At the present time, there is no way to prevent the disorder in a person who has the mutation. Identifying the child at this age as having the mutation provides no benefit. Although it is true that a child of this age could not understand or participate in the genetic counseling, if treatment was possible, it would be worth performing the test anyway.

Why Is Predictive Testing for Huntington Disease Avoided for a 4-Year-Old