Which of the Following Statements About Huntington Disease (HD)is True

Question

Which of the following statements about Huntington disease (HD)is true ?
A) The disease is caused by a high number of repeated DNA triplets.
B) The gene responsible for the disease has not been located yet.
C) As the number of repeated triplets decreases, the severity of the symptoms increases.
D) People living around Lake Maracaibo in Venezuela show a very low frequency of HD.
E) Normal copies of the HD gene only have one copy of the DNA triplet.

Accepted Answer

Huntington disease (HD) is caused by an abnormally high number of CAG triplet repeats in the huntingtin (HTT) gene. The higher the number of repeats, the earlier the onset and more severe the symptoms of the disease. This is known as anticipation, where the disease gets progressively worse over generations as more repeats are passed down from affected parents to their offspring.