Final answer:
The most common diagnostic test for Huntington's Disease is a genetic test that looks for mutations in the HTT gene. It involves a blood sample where the number of CAG repeats in the gene is analyzed. This test can diagnose HD or reveal carrier status, guiding family planning and treatment decisions.
Step-by-step explanation:
Description of Diagnostic Test for Huntington's Disease (HD)
The most common diagnostic test for Huntington's Disease (HD) is a genetic test. This test identifies mutations in the HTT gene, which is responsible for HD. A blood sample is typically used to conduct this test. During the laboratory analysis, the blood is examined to determine the number of CAG repeats in the HTT gene. An increased number of CAG repeats is indicative of Huntington's Disease. Today, this test is widely available and can confirm the diagnosis of HD in both symptomatic and asymptomatic individuals. It can also be used as a predictive test for individuals who have a family history of Huntington's Disease but are currently asymptomatic.
Moreover, genetic testing for hereditary diseases has become a pivotal method for carrier diagnosis, especially for conditions like cystic fibrosis, Tay-Sachs disease, Duchenne muscular dystrophy, and Huntington's Disease itself. Knowing one's carrier status can be crucial for making informed decisions regarding family planning and early treatment options.