Causes

If you have pseudocholinesterase deficiency, your body lacks or has a reduced amount of the enzyme needed to break down (metabolize) drugs known as choline esters. These drugs, succinylcholine and mivacurium, are used as part of anesthesia to relax the muscles during medical procedures.

Pseudocholinesterase deficiency causes the muscles to stay relaxed for too long, which prevents you from moving or breathing on your own for a few hours after receiving the drug. How long it takes your body to metabolize the medication depends on how much pseudocholinesterase enzyme is produced and how well it functions.

Pseudocholinesterase deficiency can be inherited or acquired.

Inherited pseudocholinesterase deficiency

Inherited pseudocholinesterase deficiency is caused by a defect in the butyrylcholinesterase (BCHE) gene. This gene provides the instructions to make the pseudocholinesterase enzyme that's needed to break down choline esters. This genetic defect results in a poorly functioning enzyme or lack of enzyme production.

Genetic testing can reveal whether you have this abnormal gene. To have the condition, you must inherit two abnormal genes ? one from each of your parents (autosomal recessive inheritance). If you inherit only one abnormal gene, you won't have the condition. However, you may process choline esters at a slower rate than those without an abnormal gene.

With one abnormal gene, you are a carrier and you can pass the abnormal gene to your children. But they won't develop the condition unless they also inherit an abnormal gene from the other parent.

Acquired pseudocholinesterase deficiency

Pseudocholinesterase deficiency can be acquired as a result of conditions that reduce production of the pseudocholinesterase enzyme, such as chronic infections, kidney or liver disease, malnutrition, severe burns, cancer, or pregnancy. Certain drugs also can reduce production of the enzyme, causing a deficiency.