A 7-year-old boy with compulsive self mutilation, intellectual disability. He is always strapped to bed Serum uric acid level is elevated. What is the enzyme deficiency in this disorder?
**Core Concept**
The question is testing the student's knowledge of a specific enzyme deficiency that leads to an accumulation of a particular metabolite, resulting in a distinct clinical syndrome. This disorder is characterized by self-mutilation, intellectual disability, and elevated serum uric acid levels.
**Why the Correct Answer is Right**
The correct answer involves a deficiency in the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). This enzyme plays a crucial role in the purine salvage pathway, which recycles purine bases to form nucleotides. A deficiency in HGPRT leads to the accumulation of hypoxanthine and uric acid, resulting in elevated serum uric acid levels. This condition is known as Lesch-Nyhan syndrome, characterized by self-mutilation, intellectual disability, and other systemic complications.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not relate to the disorder described. The disorder is not related to the enzyme deficiency of galactose-1-phosphate uridyltransferase, which is associated with galactosemia.
* **Option B:** This option is incorrect because it refers to a different disorder. The enzyme deficiency of pyruvate dehydrogenase is associated with pyruvate dehydrogenase deficiency, which presents with different clinical features.
* **Option C:** This option is incorrect because it refers to a different enzyme. The enzyme deficiency of glucose-6-phosphate dehydrogenase is associated with glucose-6-phosphate dehydrogenase deficiency, which presents with different clinical features.
* **Option D:** This option is incorrect because it does not relate to the disorder described. The disorder is not related to the enzyme deficiency of succinate dehydrogenase, which is associated with different clinical features.
**Clinical Pearl / High-Yield Fact**
Lesch-Nyhan syndrome is an X-linked recessive disorder, which means it predominantly affects males. The elevated serum uric acid levels in this disorder can lead to kidney stones and other systemic complications. Early diagnosis and management are crucial to prevent these complications.
**Correct Answer:** C. HGPRT (Hypoxanthine-Guanine Phosphoribosyltransferase) deficiency.