Final answer:
Presymptomatic testing for Huntington's Disease is commonly conducted during adolescence or early adulthood, especially when there is a known family history of the disorder.
Step-by-step explanation:
Presymptomatic testing for Huntington's Disease (HD) is usually performed during adolescence or early adulthood. This type of testing is done prior to the onset of symptoms and is usually considered when an individual has a known family history of HD, which is a neurodegenerative genetic disorder. In HD, individuals who are heterozygous for the dominant Huntington allele (Hh) are at risk of developing the disease, often around the age of 40. Therefore, the correct answer to when presymptomatic testing for HD is performed is C) Adolescence or early adulthood. However, the symptoms may not appear until later in life, usually around the age of 40.
Therefore, presymptomatic testing is done during adolescence or early adulthood to determine if someone carries the HD allele before symptoms emerge. This allows individuals to make informed decisions about their health and future.