A metabolic disorder involving an enzyme (butyrylcholinesterase) deficiency. It results in prolonged recovery from the effects of certain anesthetics such as succinylcholine and mivacurium which are muscle relaxants. The severity of the deficiency will determine the length of time taken to recover from anesthetic. In severe cases, patients can take more than 8 hours to recover. See also Butyrylcholinesterase deficiency