Question

A 15-year-old child with difficulty in exercise, affected oxidation of long-chain fatty acids, and biopsy of muscle shows fat vacuoles. Which of the following is the diagnosis?

• A. Carnitine deficiency
• B. FA synthase defect
• C. LPL defect
• D. LDL defect

Hint:

Carnitine deficiency prevents the proper oxidation of long-chain fatty acids, leading to the accumulation of fat in muscle tissue and exercise intolerance.

Answer 1

The Correct Option is A

The presented case involves a 15-year-old child experiencing difficulty during exercise due to impaired oxidation of long-chain fatty acids, with a muscle biopsy revealing fat vacuoles. This set of symptoms and findings points towards a diagnosis of Carnitine deficiency. Let's explore why:

1. Difficulty in exercise: This indicates a problem where energy from fatty acid metabolism is not being efficiently used, often due to a defect in transporting fatty acids into the mitochondria for β-oxidation.
2. Oxidation of long-chain fatty acids: In normal physiology, long-chain fatty acids are transported into the mitochondria by carnitine. A deficiency in carnitine results in impaired fatty acid oxidation, hence the symptoms.
3. Muscle biopsy showing fat vacuoles: The accumulation of fat in muscle cells indicates that fatty acids are not being metabolized properly, typical of a disorder affecting fatty acid transport or oxidation.

Given these points, carnitine deficiency is consistent with all symptoms described, as it is responsible for the transport of long-chain fatty acids into the mitochondria, essential for their oxidation and subsequent energy production. Other options involve different pathways and do not align with the symptomatology or metabolic finding in this scenario.