1. an aminoacidopathy characterized by excess of propionic acid and glycine in the blood and urine, ketosis, acidosis, and often neurologic complications, due to deficiency of an enzyme involved in amino acid and fatty acid catabolism.
2. excess of propionic acid in the blood.
Etymology: Gk, pro + pion, fat; L, acidus, sour; Gk, haima, blood
a rare inherited metabolic defect caused by the failure of the body to metabolize the amino acids threonine, isoleucine, and methionine, characterized by lethargy and mental and physical retardation. Acidosis results from the accumulation of propionic acid in the body. A diet low in these amino acids is difficult to achieve but is the only treatment. propionicacidemic, adj.