Which inheritance pattern does Huntington disease follow?

Which inheritance pattern does Huntington disease follow?

• A. Autosomal recessive
• B. Autosomal dominant
• C. X-linked dominant
• D. Mitochondrial inheritance

Answer: (B)

Huntington disease is inherited in an autosomal dominant manner. That means a single mutated copy of the HTT gene on an autosome is enough to cause disease, and each child of an affected parent has a 50% chance of inheriting the condition, with no bias toward either sex. The disorder is due to a CAG trinucleotide repeat expansion in HTT on chromosome 4, and it often shows anticipation—earlier onset in subsequent generations, especially with paternal transmission. This pattern distinguishes it from autosomal recessive conditions (two mutated copies needed), X-linked dominant conditions (related to the X chromosome with different sex-specific patterns), or mitochondrial inheritance (maternal transmission to all children).

Huntington disease is inherited in an autosomal dominant manner. That means a single mutated copy of the HTT gene on an autosome is enough to cause disease, and each child of an affected parent has a 50% chance of inheriting the condition, with no bias toward either sex. The disorder is due to a CAG trinucleotide repeat expansion in HTT on chromosome 4, and it often shows anticipation—earlier onset in subsequent generations, especially with paternal transmission. This pattern distinguishes it from autosomal recessive conditions (two mutated copies needed), X-linked dominant conditions (related to the X chromosome with different sex-specific patterns), or mitochondrial inheritance (maternal transmission to all children).