This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
All of the following are characterized by trinucleotide repeat affecting the job coding regions except 
Select and explain. 
A. Friedrich ataxia, B. Fragile X syndrome, C. Huntington disease, D. Myotonic dystrophy
C: Huntington disease
Answer: C: Huntington disease 
Explanation: ref Robbins 9/e p168 Huntington disease is characterized by trinucleotide repeat affecting the coding region.rest all conditions mentioned in the options affects the non coding regions