Huntington's disease is caused by

  1. an X-linked recessive allele
  2. a recessive allele of HBB
  3. a mutation in TYR
  4. a dominant allele of HTT with extra CAG repeats
Answer

D) a dominant allele of HTT with extra CAG repeats

Huntingtin with extra glutamines. AS & A Level Biology · Topic 16 Inheritance · 16.2 The roles of genes in determining the phenotype

Biology MCQ · More A Level Biology: Inheritance MCQs · Practise