- Type 2 muscle fiber atrophy (HP:0003554): Atrophy (wasting) affecting primary type 2 muscle fibers. This feature in general can only be observed on muscle biopsy. Evidence: IEA. (OMIM:159400)
- Neoplasm (HP:0002664): An organ or organ-system abnormality that consists of uncontrolled autonomous cell-proliferation which can occur in any part of the body as a benign or malignant neoplasm (tumor). Evidence: IEA. (OMIM:159400)
- Fatigable weakness (HP:0003473): 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. Evidence: IEA. (OMIM:159400)
- Adult onset (HP:0003581): Onset of disease manifestations in adulthood, defined here as at the age of 16 years or later. Evidence: IEA. (OMIM:159400)
- Mildly elevated creatine kinase (HP:0008180). Evidence: IEA. (OMIM:159400)
- Thymoma (HP:0100522): A tumor originating from the epithelial cells of the thymus. Evidence: TAS. (OMIM:159400)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: IEA. (OMIM:159400)
- Proximal amyotrophy (HP:0007126): Amyotrophy (muscular atrophy) affecting the proximal musculature. Evidence: IEA. (OMIM:159400)
- Systemic lupus erythematosus (HP:0002725): A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys, and serosal membranes. Evidence: IEA. (OMIM:159400)
- Sporadic (HP:0003745): Cases of the disease in question occur without a previous family history, i.e., as isolated cases without being transmitted from a parent and without other siblings being affected. Evidence: IEA. (OMIM:159400)
- Ophthalmoparesis (HP:0000597): Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement. Evidence: IEA. (OMIM:159400)
- Hashimoto thyroiditis (HP:0000872): A chronic, autoimmune type of thyroiditis associated with hypothyroidism. Evidence: IEA. (OMIM:159400)
- EMG: decremental response of compound muscle action potential to repetitive nerve stimulation (HP:0003403): A compound muscle action potential (CMAP) is a type of electromyography (EMG). CMAP refers to a group of almost simultaneous action potentials from several muscle fibers in the same area evoked by stimulation of the supplying motor nerve and are recorded as one multipeaked summated action potential. This abnormality refers to a greater than normal decrease in the amplitude during the course of the investigation. Evidence: IEA. (OMIM:159400)
These phenotypes are associated with the disease myasthenia, limb-girdle, autoimmune (OMIM:159400).