Phenotypes associated with the disease congenital myasthenic syndrome 6 (OMIM:254210):
- 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:254210)
- Apneic episodes precipitated by illness, fatigue, stress (HP:0002872): Recurrent episodes of apnea that are precipitated by factors such as illness, fatigue, or stress. Evidence: IEA. (OMIM:254210)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: IEA. (OMIM:254210)
- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 20/20. (PMID:11172068;OMIM:254210)
- Strabismus (HP:0000486): A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error. Evidence: IEA. (OMIM:254210)
- Sudden episodic apnea (HP:0002882): Recurrent bouts of sudden, severe apnea that may be life-threatening. Evidence: IEA. (OMIM:254210)
- Respiratory distress (HP:0002098): Respiratory distress is objectively observable as the physical or emotional consequences from the experience of dyspnea. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea. Evidence: IEA. (OMIM:254210)
- 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: PCS. Frequency: 5/5. (PMID:11172068)
- Bulbar palsy (HP:0001283): Bulbar weakness (or bulbar palsy) refers to bilateral impairment of function of the lower cranial nerves IX, X, XI and XII, which occurs due to lower motor neuron lesion either at nuclear or fascicular level in the medulla or from bilateral lesions of the lower cranial nerves outside the brain-stem. Bulbar weakness is often associated with difficulty in chewing, weakness of the facial muscles, dysarthria, palatal weakness and regurgitation of fluids, dysphagia, and dysphonia. Evidence: PCS. Frequency: 5/5. (PMID:11172068)
- Poor suck (HP:0002033): An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed. Evidence: IEA. (OMIM:254210)
- Generalized hypotonia due to defect at the neuromuscular junction (HP:0003397). Evidence: IEA. (OMIM:254210)
- 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: 0/5. (PMID:11172068)
- 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:254210)
- 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:11172068)
- Arthrogryposis multiplex congenita (HP:0002804): Multiple congenital contractures in different body areas. Evidence: IEA. (OMIM:254210)
- Respiratory insufficiency due to muscle weakness (HP:0002747). Evidence: IEA. (OMIM:254210)
- Ophthalmoparesis (HP:0000597): Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement. Evidence: IEA. (OMIM:254210)
- Weak cry (HP:0001612). Evidence: IEA. (OMIM:254210)
- Decreased miniature endplate potentials (HP:0003402): An abnormal reduction in the amplitude of the miniature endplate potentials, i.e. the postsynaptic response to transmitter released from an individual vesicle at the neuromuscular junction. Evidence: PCS. Frequency: 2/2. (PMID:11172068)
- 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:254210)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. (PMID:11172068)