AChR (Acetylcholine Receptor) Binding Antibody Test

This test measures the Acetylcholine receptor (AChR) Binding antibodies in the blood to screen for Myasthenia Gravis (MG). This test also helps to determine if an individual may have MG or another condition with similar symptoms.

Individuals can move their muscles when an impulse is transferred to the nerve endings and prompts the release of acetylcholine. Acetylcholine is a chemical substance (neurotransmitter) that transmits messages between specific types of cells. The neurotransmitter passes through a tiny gap between the nerve end and muscle fibers (known as the “neuromuscular junction”). So, when acetylcholine makes it to the muscle fiber, it binds to one of many acetylcholine receptors and triggers it, prompting muscle movement.

However, AChR antibodies are autoantibodies created by the immune system that incorrectly targets the skeletal muscles. An example is when the AChR antibodies obstruct communication between nerves and skeletal muscles, which hinders muscle movement and causes rapid muscle fatigue by preventing activation of the acetylcholine receptors.

Acetylcholine receptors are obstructed in three significant ways, including:

• AChR Binding antibodies attach to nerve cell receptors and may prompt inflammation that destroys the receptors.
• AChR Blocking antibodies may sit on the receptors, preventing acetylcholine from binding.
• AChR Modulating antibodies cross-link the receptors, which causes them to be absorbed into the muscle cell and removed from the neuromuscular junction.

These interferences cause the development of Myasthenia Gravis (MG), a chronic autoimmune disorder associated with the presence of these antibodies and their effects on muscle movement.

This specific test measures the “binding” antibodies and is the most performed test to screen for potential MG development. Common symptoms of Myasthenia Gravis include:

• weak eye movement
• drooping eyelids
• blurred or double vision
• a change in facial expression
• difficulty swallowing
• shortness of breath
• impaired speech
• weakness in the arms, hands, fingers, legs, and neck