Congenital lactic acidosis occur due to the deficiency of which of the following enzyme?
**Core Concept**
Congenital lactic acidosis, also known as pyruvate dehydrogenase complex (PDH) deficiency, is a rare genetic disorder that leads to an accumulation of lactic acid in the body due to impaired pyruvate metabolism. This condition is characterized by recurrent episodes of lactic acidosis, often triggered by fasting, illness, or stress.
**Why the Correct Answer is Right**
The correct answer is **C. Pyruvate Dehydrogenase Complex (PDH)**. Pyruvate dehydrogenase complex is a crucial enzyme that catalyzes the conversion of pyruvate to acetyl-CoA, a key step in the Krebs cycle. In the absence of PDH, pyruvate accumulates and is converted to lactic acid, leading to lactic acidosis. This enzyme deficiency is caused by mutations in the PDHA1 or PDHB genes, which code for the E1α and E2 components of the PDH complex, respectively.
**Why Each Wrong Option is Incorrect**
**Option A:** **Alpha-Ketoglutarate Dehydrogenase Complex (KGDHC)** is another enzyme involved in the Krebs cycle, but its deficiency is not associated with congenital lactic acidosis.
**Option B:** **Isocitrate Dehydrogenase (IDH)** is an enzyme involved in the Krebs cycle, but its deficiency is not directly related to lactic acidosis.
**Option D:** **Malate Dehydrogenase (MDH)** is an enzyme involved in the Krebs cycle, but its deficiency is not associated with congenital lactic acidosis.
**Clinical Pearl / High-Yield Fact**
Pyruvate dehydrogenase complex deficiency can be treated with thiamine supplementation, as thiamine is a cofactor for the PDH complex. However, this treatment may not always be effective, and other interventions, such as dietary restrictions and medication, may be necessary to manage the condition.
**Correct Answer: C. Pyruvate Dehydrogenase Complex (PDH)**