b-hydroxybutyric aciduria is associated with deficiency of
**Core Concept**
Beta-hydroxybutyric aciduria is a rare disorder characterized by the accumulation of beta-hydroxybutyrate in the urine due to a defect in the metabolism of fatty acids. This condition is related to the deficiency of an enzyme involved in the breakdown of fatty acids.
**Why the Correct Answer is Right**
The correct answer is related to the enzyme D-bifunctional protein, which is a key player in the beta-oxidation of fatty acids. D-bifunctional protein is responsible for the conversion of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) to 3-hydroxy-3-methylglutarate, a step that is crucial for the breakdown of fatty acids. A deficiency in D-bifunctional protein leads to the accumulation of beta-hydroxybutyrate, resulting in beta-hydroxybutyric aciduria.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because succinyl-CoA synthetase is an enzyme involved in the citric acid cycle, not in the breakdown of fatty acids.
* **Option B:** This option is incorrect because 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase is an enzyme involved in the synthesis of HMG-CoA from acetyl-CoA and acetoacetyl-CoA, not in its breakdown.
* **Option C:** This option is incorrect because alpha-ketoglutarate dehydrogenase is an enzyme involved in the citric acid cycle, not in the breakdown of fatty acids.
**Clinical Pearl / High-Yield Fact**
D-bifunctional protein deficiency should be suspected in patients with beta-hydroxybutyric aciduria, particularly those with a history of seizures, developmental delay, and failure to thrive. Early diagnosis and treatment are crucial to prevent the progression of the disease.
**Correct Answer: D. D-bifunctional protein**