Muscle weakness Abnormal synaptic transmission at the neuromuscular junction Fatigable weakness Proximal muscle weakness due to defect at the neuromuscular junction Fatigable weakness of limb muscles Generalised muscle weakness due to defect at the neuromuscular junction UMLS:C0947912 HP:0003428 HP:0100794 Myasthenic weakness A type of weakness that occurs after a muscle group is used and lessens if the muscle group has some rest. That is, there is diminution of strength with repetitive muscle actions. This type of weakness is pathognomonic for an abnormality of the neuromuscular junction such as myasthenia gravis. A characteristic form of muscular weakness that worsens after use of affected muscles. Myasthenia is caused by failure of neuromuscular transmission, which results from the binding of autoantibodies to proteins involved in signaling at the neuromuscular junction, including especially the nicotinic acetyl choline receptor (AChR) or, less frequently, a muscle-specific tyrosine kinase involved in AChR clustering. Myasthenia HP:0003473 Generalized muscle weakness due to defect at the neuromuscular junction HP:0003399