Question

Werner syndrome associated with premature aging is caused due to a defect in which of the following ?

• A. Telomerase
• B. Caspase
• C. DNA topoisomerase
• D. DNA helicase

Answer 1

The Correct Option is D

Tie the name to the gene: Werner syndrome equals the WRN gene, and WRN encodes a RecQ DNA helicase. That single link answers the question, option 4.
The clinical picture is one of accelerated aging, premature graying, thin hair, taut wrinkled skin, leg ulcers, early cataracts, atherosclerosis, osteoporosis, plus a raised risk of type 2 diabetes and cancers. All of this stems from a faulty helicase that cannot properly unwind DNA for repair and replication, leaving the genome unstable.
Rule out the rest: telomerase mutations underlie dyskeratosis congenita, caspases drive apoptosis, and topoisomerases relieve supercoiling, none of which produce the Werner phenotype. So DNA helicase is correct.
Ref: WRN gene, RecQ helicase family.