Werner syndrome is –
**Core Concept**
Werner syndrome, also known as adult progeria, is a rare genetic disorder characterized by premature aging and increased risk of cancer. It is an autosomal recessive disorder caused by mutations in the WRN gene, which encodes a RecQ DNA helicase involved in DNA repair and replication.
**Why the Correct Answer is Right**
Werner syndrome is caused by mutations in the WRN gene, leading to impaired DNA repair mechanisms. This results in increased genetic instability, premature aging, and a higher risk of developing cancer. The WRN protein plays a crucial role in maintaining genome stability by resolving DNA replication and repair intermediates, and its deficiency leads to accumulation of DNA damage.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might be a distractor related to another genetic disorder, such as Hutchinson-Gilford progeria syndrome, which is a different condition caused by mutations in the LMNA gene.
**Option B:** This option could be related to a different type of DNA repair disorder, such as Bloom syndrome, which is caused by mutations in the BLM gene but has distinct clinical and pathological features.
**Option C:** This option might be a distractor related to a non-genetic cause of premature aging, such as premature aging associated with HIV infection or other chronic diseases.
**Clinical Pearl / High-Yield Fact**
Werner syndrome is an autosomal recessive disorder, meaning that both parents are carriers of the mutated WRN gene, and each child has a 25% chance of inheriting two copies of the mutated gene, resulting in the condition.
**Correct Answer:** D.