What is Huntington's disease?

What is Huntington's disease?

• A. Caused by repeated DNA sequence; affects the nervous system
• B. Caused by a single nucleotide substitution; affects blood
• C. Caused by a chromosomal deletion; affects lungs
• D. Caused by a viral infection; affects immune system

Answer: (A)

Huntington's disease is a hereditary neurodegenerative disorder caused by an expansion of a trinucleotide repeat in the HTT gene. Specifically, extra repeats of a DNA sequence (CAG) lead to an abnormal huntingtin protein that damages neurons, producing the characteristic motor, cognitive, and psychiatric symptoms. This disease is inherited in an autosomal dominant pattern and shows anticipation, with earlier onset as the repeat length increases across generations. Because the root cause is a repeated DNA sequence that affects the nervous system, the described mechanism fits Huntington's disease. The other options describe different kinds of mutations or infections that would affect other tissues, which is not how Huntington's presents.

Huntington's disease is a hereditary neurodegenerative disorder caused by an expansion of a trinucleotide repeat in the HTT gene. Specifically, extra repeats of a DNA sequence (CAG) lead to an abnormal huntingtin protein that damages neurons, producing the characteristic motor, cognitive, and psychiatric symptoms. This disease is inherited in an autosomal dominant pattern and shows anticipation, with earlier onset as the repeat length increases across generations. Because the root cause is a repeated DNA sequence that affects the nervous system, the described mechanism fits Huntington's disease. The other options describe different kinds of mutations or infections that would affect other tissues, which is not how Huntington's presents.