Anti-neuromuscular Junction acetylcholine receptor antibody positivity

What it means

The presence of autoantibodies (immunoglobulins) in the blood circulation that react against neuromuscular junction acetylcholine receptors.

The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle. Acetylcholine (ACh) is synthesized in the pre-synaptic terminal using choline and acetyl-CoA and the enzyme choline acetyltransferase. The released ACh subsequently binds to nicotinic ACh receptors on the junctional folds of the motor endplate. The binding of ACh to receptors triggers the opening of ACh gated ion channels that allow the influx of sodium ions into the muscle. Myasthenia Gravis is an auto-immune condition (type II hypersensitivity reaction), resulting in the production of auto-antibodies against ACh receptors, at the neuromuscular junction.

Rare diseases that can present with this3

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 3 diseases where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Acetylcholine receptor antibody positivity · Anti-AChR antibody positivity