- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 3/3. (PMID:10562302)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: PCS. Frequency: 3/3. (PMID:10562302)
- Myopathy (HP:0003198): A disorder of muscle unrelated to impairment of innervation or neuromuscular junction. Evidence: IEA. (OMIM:616314)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: TAS. Onset: Neonatal onset (HP:0003623). (OMIM:616314)
- Autosomal recessive inheritance (HP:0000007): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:10562302)
- Neonatal hypotonia (HP:0001319): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period. Evidence: TAS. (OMIM:616314)
- Respiratory insufficiency (HP:0002093). Evidence: PCS. Frequency: 3/3. (PMID:10562302)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. (OMIM:616314)
- Anti-neuromuscular Junction acetylcholine receptor antibody positivity (HP:0030208): The presence of autoantibodies (immunoglobulins) in the blood circulation that react against neuromuscular junction acetylcholine receptors. Evidence: PCS. Frequency: 0/1. (PMID:10562302)
- 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: PCS. Frequency: 1/1. (PMID:10562302)
These phenotypes are associated with the disease congenital myasthenic syndrome 2C (OMIM:616314).