Final answer:
The age range of onset of clinical features of HD is typically between 30 to 50 years old, but can vary from 20s to 60s. HD is a genetic disorder caused by a dominant allele.
Step-by-step explanation:
The age range of onset of clinical features of Huntington's disease (HD) is typically between 30 to 50 years old. However, in some cases, the onset may occur as early as the 20s or as late as the 60s. HD is a genetic disorder caused by a dominant allele, and individuals who inherit this allele have a high likelihood of developing the disease at some point in their life.