Which type of inheritance is Huntington disease classified under?

• A. Autosomal Dominant
• B. Autosomal Recessive
• C. X-linked Dominant
• D. X-linked Recessive

Answer: (A)

Huntington disease is classified as autosomal dominant inheritance because it is caused by a mutation in a single gene located on one of the non-sex chromosomes (autosomes). In the case of Huntington disease, if an individual inherits the mutated gene from just one parent, they will typically develop the disease. This pattern of inheritance means that the condition can be passed down through generations with a 50% chance of an affected parent transmitting the mutated allele to their offspring.

The autosomal dominant nature of Huntington disease also explains why it tends to manifest in mid-adulthood, as symptoms often do not appear until later in life, allowing individuals to pass the gene to the next generation before they are aware of having the condition. This mode of inheritance contrasts with autosomal recessive disorders, which require two copies of the mutated gene for the disease to manifest, or with X-linked conditions, where the gene is located on the X chromosome and typically exhibits different patterns of inheritance based on gender.