Question

Carnitine, a natural substance acquired mostly through the diet, is used by cells to process fats and produce energy. Carnitine transporter deficiency (CTD) is an inborn error of fatty acid transport, resulting in reduced free carnitine and increased plasma acylcarnitine within hepatocytes (liver cells). Additionally, those affected by CTD are often in a state of hypoglycemia. Using your biochemical knowledge, briefly explain:

(i) How the aforementioned symptoms of CTD prevent fatty acid metabolism?

(ii) Why is hypoglycemia observed within diseased individuals?

Answer 1

i) The main function of carnitine is the transfer of long chain fatty acids to mitochondria for subsequent beta oxidation. mitochondrial membrane is impermeable to acyl CoA and fatty acid must be conjugated with carnitine to enter into mitochondria. Carnitine deficiency impairs entry of fatty acid into mitochondria and fatty acid will not be available for beta oxidation. Hence there will not be any production of energy and ketone bodies.

ii) Genetic carnitine palmitoyl transferase 1 deficiency effects liver which results in decreased or inability of liver to synthezise glucoe during fasting. This results in hypoglycemeia.