Question

Which one of the following is an autosomal dominant disorder?

• A. Sickle cell anaemia
• B. Cystic fibrosis
• C. Tay-Sachs disease
• D. Huntington's disease

Hint:

Most "famous" genetic diseases are recessive; Huntington's is a notable dominant exception.

Answer 1

The Correct Option is D

Step 1: Concept
Autosomal dominant disorders occur when only one copy of an altered gene in each cell is sufficient to cause the disorder.

Step 2: Meaning
Autosomal recessive disorders (like Sickle cell, Cystic fibrosis, and Tay-Sachs) require two copies of the mutated gene.

Step 3: Analysis
Huntington's disease is caused by a CAG repeat expansion in the HTT gene. It follows a dominant inheritance pattern, meaning an affected parent has a 50% chance of passing it to their offspring.

Step 4: Conclusion
Therefore, Huntington's disease is the correct autosomal dominant example. Final Answer: (D)