Phenotypes associated with the disease congenital myasthenic syndrome 4C (OMIM:608931):
- 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:608931)
- Facial palsy (HP:0010628): Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form. Evidence: IEA. (OMIM:608931)
- 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:608931)
- 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: TAS. Frequency: 20/20. (OMIM:608931)
- Decreased muscle mass (HP:0003199). Evidence: IEA. (OMIM:608931)
- 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. (OMIM:608931)
- Muscle spasm (HP:0003394): Sudden and involuntary contractions of one or more muscles. Evidence: IEA. (OMIM:608931)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: IEA. (OMIM:608931)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:608931)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: IEA. (OMIM:608931)
- Gowers sign (HP:0003391): A phenomenon whereby patients are not able to stand up without the use of the hands owing to weakness of the proximal muscles of the lower limbs. Evidence: IEA. (OMIM:608931)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/1. (PMID:8957026)
- Variable expressivity (HP:0003828): A variable severity of phenotypic features. Evidence: IEA. (OMIM:608931)
- High palate (HP:0000218): Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective). Evidence: IEA. (OMIM:608931)
- Ophthalmoparesis (HP:0000597): Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement. Evidence: PCS. Frequency: 1/1. (PMID:8957026)
- 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:8957026)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: TAS. (OMIM:608931)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: IEA. (OMIM:608931)
- Long face (HP:0000276): Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective). Evidence: IEA. (OMIM:608931)
- Easy fatigability (HP:0003388): Increased susceptibility to fatigue. Evidence: IEA. (OMIM:608931)
- Decreased size of nerve terminals (HP:0003443): A reduction in the size of nerve terminals. Evidence: IEA. (OMIM:608931)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: TAS. (OMIM:608931)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: IEA. (OMIM:608931)
- Nonprogressive (HP:0003680): Applies to a disease manifestation that does not increase in scope or severity over the course of time, i.e., that does not worsen with age. Evidence: IEA. (OMIM:608931)
- 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: PCS. Frequency: 1/1. (PMID:8957026)
- 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:8957026)
- Dental malocclusion (HP:0000689): Dental malocclusion refers to an abnormality of the occlusion, or alignment, of the teeth and the way the upper and lower teeth fit together, resulting in overcrowding of teeth or in abnormal bite patterns. Evidence: IEA. (OMIM:608931)
- Decreased fetal movement (HP:0001558): An abnormal reduction in quantity or strength of fetal movements. Evidence: IEA. (OMIM:608931)
- Arthrogryposis multiplex congenita (HP:0002804): Multiple congenital contractures in different body areas. Evidence: IEA. (OMIM:608931)
- Respiratory insufficiency due to muscle weakness (HP:0002747). Evidence: IEA. (OMIM:608931)
- Mandibular prognathia (HP:0000303): Abnormal prominence of the chin related to increased length of the mandible. Evidence: IEA. (OMIM:608931)
- Weak cry (HP:0001612). Evidence: IEA. (OMIM:608931)