2-Oxoadipic acid is produced from lysine in the cytosol of cells via the saccharopine and the pipecolic acid pathways. Catabolites of hydroxylysine and tryptophan enter these pathways as 2-aminoadipic-semialdehyde and 2-oxoadipate, respectively. In the mitochondrial matrix, 2-oxoadipate is decarboxylated to glutaryl-CoA by the 2-oxoadipate dehydrogenase complex and then converted into acetyl-CoA. Chronically high levels of oxoadipic acid are associated with at least two inborn errors of metabolism, including 2-aminoadipic aciduria and 2-oxoadipic aciduria. 2-Oxoadipic aciduria is an inborn error of metabolism involving lysine, tryptophan, and hydroxylysine, in which abnormal quantities of 2-aminoadipic acid are found in body fluids along with 2-oxoadipic acid. Patients with 2-oxoadipic acidemias are mentally retarded with hypotonia or seizures. 2-Oxoadipic aciduria can occur in patients with Kearns-Sayre syndrome, a progressive disorder with onset prior to 20 years of age in which multiple organ systems are affected. Affected individuals have progressive external ophthalmoplegia (PEO) and retinopathy, both of which are classically associated with abnormalities in cardiac conduction, cerebellar signs, and elevated cerebrospinal fluid protein (PMID: 10655159, 16183823, 11083877). When present in sufficiently high levels, oxoadipic acid can act as an acidogen and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Oxoadipic acid is an organic acid. Abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart abnormalities, kidney abnormalities, liver damage, seizures, coma, and possibly death. These are also the characteristic symptoms of the untreated IEMs mentioned above. Many affected children with organic acidemias experience intellectual disability or delayed development. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures.