Which enzyme deficiency is primarily responsible for Methylmalonic Acidemia?

Methylmalonic Acidemia is primarily caused by a deficiency in Methylmalonyl CoA mutase, which is an enzyme critical for the metabolism of certain amino acids and fatty acids. This enzyme converts methylmalonyl-CoA to succinyl-CoA, a necessary step in the pathway that leads to the energy production from these nutrients. When there is a deficiency in Methylmalonyl CoA mutase, it leads to a buildup of methylmalonic acid in the bloodstream, which can cause a range of metabolic disturbances.

While other enzymes mentioned are associated with different metabolic disorders, they do not play a role in the specific pathology of Methylmalonic Acidemia. Propionyl-CoA carboxylase is involved in the metabolism of fatty acids and amino acids but is not the direct cause of this condition. Ornithine transcarbamylase is involved in the urea cycle and causes a different metabolic disorder. Alpha-galactosidase A is related to Fabry disease, which is unrelated to the metabolism impacted in Methylmalonic Acidemia. Thus, understanding the role of Methylmalonyl CoA mutase in the metabolic pathway is crucial to recognizing why its deficiency