Question

For very large number of repeats in Huntington’s disease, the phenotype can appear at 20 years of age.

(a) True

(b) False

This question was posed to me during an online exam.

Query is from Dynamic Mutation and Anticipation topic in section Nuclear Export & Post Mendelian Genetics of Cytogenetics

Answer 1

Right option is (a) True

Easiest explanation: Huntigton’s is an X linked dominant disease that is expressed in an individual beyond 30 years of age if they have more than 36 CAG repeats. If the number of repeats of CAG is much more the gene can find its expression at 20 years of age as well.