Propionic Acidemia [E71.1]
Dipl.-Biol. Birgit Busse
Propionic acidemia is a rare autosomal recessive inherited metabolic disorder belonging to the group of organic acidurias. The disorder is caused by a deficiency in the enzyme propionyl-CoA carboxylase as a result of mutations in the genes of the alpha and beta subunit (PCCA and PCCB) of the enzyme. Thus the conversion of propionyl-CoA to methylmalonyl-CoA is disrupted and the accumulation of propionyl-CoA and its metabolites, which are partially detectable in blood and urine. An increased concentration of propionyl-CoA results in excessive binding of coenzyme A, whereby various metabolic pathways in the mitochondria are disturbed.
Symptoms are similar to methylmalonic aciduria (ketoacidotic coma, hyperammonemia, seizures) and usually appear soon after birth. A later onset is associated with, among other symptoms, hyptonia, digestive disorders, recurrent comatose states and mental retardation. Furthermore, in addition to acute metabolic disorders, neurological symptoms, cardiomyopathy and acute pancreatitis are additional complications of the enzyme deficiency. The symptom spectrum is extensive and can affect various organ systems. A diagnosis is made primarily by laboratory tests. A genetic test is used to confirm a suspected diagnosis.