Phenotypes associated with the disease congenital myasthenic syndrome 9 (OMIM:616325):
- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 1/1. (PMID:20371544)
- 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: 1/1. (PMID:15496425)
- Flexion contracture (HP:0001371): A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints. Evidence: PCS. Frequency: 0/1. (PMID:23326516)
- Anti-muscle-specific tyrosine kinase antibody (HP:0030210): The presence of autoantibodies (immunoglobulins) in the serum that react against muscle specific kinase (anti-MuSK Ab). Evidence: PCS. Frequency: 0/2. (PMID:15496425;PMID:20371544)
- 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:616325)
- 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: PCS. Frequency: 1/1. (PMID:20371544)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: TAS. (OMIM:616325)
- Fasciculations (HP:0002380): Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units. Evidence: PCS. Frequency: 0/1. (PMID:23326516)
- 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: PCS. Frequency: 5/6. (PMID:23326516;PMID:19949040)
- Weakness of facial musculature (HP:0030319): Reduced strength of one or more muscles innervated by the facial nerve (the seventh cranial nerve). Evidence: PCS. Frequency: 6/6. (PMID:19949040;PMID:20371544)
- Tongue atrophy (HP:0012473): Wasting of the tongue. Evidence: PCS. Frequency: 1/1. (PMID:23326516)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 6/6. (PMID:23326516;PMID:19949040)
- Hyperlordosis (HP:0003307): Abnormally increased curvature (anterior concavity) of the lumbar or cervical spine. Evidence: PCS. Frequency: 2/5. (PMID:19949040)
- Waddling gait (HP:0002515): Weakness of the hip girdle and upper thigh muscles, for instance in myopathies, leads to an instability of the pelvis on standing and walking. If the muscles extending the hip joint are affected, the posture in that joint becomes flexed and lumbar lordosis increases. The patients usually have difficulties standing up from a sitting position. Due to weakness in the gluteus medius muscle, the hip on the side of the swinging leg drops with each step (referred to as Trendelenburg sign). The gait appears waddling. The patients frequently attempt to counteract the dropping of the hip on the swinging side by bending the trunk towards the side which is in the stance phase (in the German language literature this is referred to as Duchenne sign). Similar gait patterns can be caused by orthopedic conditions when the origin and the insertion site of the gluteus medius muscle are closer to each other than normal, for instance due to a posttraumatic elevation of the trochanter or pseudarthrosis of the femoral neck. Evidence: PCS. Frequency: 2/6. (PMID:23326516;PMID:19949040)
- Axial muscle weakness (HP:0003327): Reduced strength of the axial musculature (i.e., of the muscles of the head and neck, spine, and ribs). Evidence: PCS. Frequency: 1/1. (PMID:23326516)
- Shoulder girdle muscle weakness (HP:0003547): The shoulder, or pectoral, girdle is composed of the clavicles and the scapulae. Shoulder-girdle weakness refers to lack of strength of the muscles attaching to these bones, that is, lack of strength of the muscles around the shoulders. Evidence: PCS. Frequency: 2/5. (PMID:19949040)
- Proximal upper limb muscle weakness (HP:0008997): A lack of strength of the proximal muscles of the arms. Evidence: PCS. Frequency: 3/8. (PMID:23326516;PMID:19949040;PMID:15496425;PMID:20371544)
- 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: 2/3. (PMID:23326516;PMID:15496425;PMID:20371544)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 1/1. (PMID:15496425)
- Upgaze palsy (HP:0025331): A limitation of the ability to direct one's gaze above the horizontal meridian. Evidence: PCS. Frequency: 2/2. (PMID:23326516;PMID:20371544)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: PCS. Frequency: 1/3. (PMID:23326516;PMID:15496425;PMID:20371544)
- Generalized muscle weakness (HP:0003324): Generalized weakness or decreased strength of the muscles, affecting both distal and proximal musculature. Evidence: PCS. Frequency: 1/1. (PMID:15496425)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 1/2. (PMID:23326516;PMID:20371544)
- Easy fatigability (HP:0003388): Increased susceptibility to fatigue. Evidence: PCS. Frequency: 7/7. (PMID:23326516;PMID:15496425;PMID:19949040)
- Respiratory insufficiency (HP:0002093). Evidence: PCS. Frequency: 3/7. (PMID:19949040;PMID:15496425;PMID:20371544)
- 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: 0/3. (PMID:23326516;PMID:15496425;PMID:20371544)
- Sleep apnea (HP:0010535): An intermittent cessation of airflow at the mouth and nose during sleep is known as sleep apnea. Apneas that last at least 10 seconds are considered significant, but individuals with sleep apnea may experience apneas lasting from 20 seconds up to 2 or 3 minutes. Patients may have up to 15 events per hour of sleep. Evidence: PCS. Frequency: 1/1. (PMID:23326516)
- 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: 8/8. (PMID:23326516;PMID:19949040;PMID:15496425;PMID:20371544)
- Ophthalmoplegia (HP:0000602): Paralysis of one or more extraocular muscles that are responsible for eye movements. Evidence: PCS. Frequency: 6/6. (PMID:19949040;PMID:15496425)
- 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:15496425)
- Neonatal hypotonia (HP:0001319): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period. Evidence: TAS. (OMIM:616325)
- Distal lower limb amyotrophy (HP:0008944): Muscular atrophy of distal leg muscles. Evidence: PCS. Frequency: 1/1. (PMID:23326516)
- Hypernasal speech (HP:0001611): A type of speech characterized by the presence of an abnormally increased nasal airflow during speech associated with structural abnormality of the nasal passages. Evidence: PCS. Frequency: 2/7. (PMID:15496425;PMID:19949040;PMID:20371544)
- Neck muscle weakness (HP:0000467): Decreased strength of the neck musculature. Evidence: PCS. Frequency: 13/17. (OMIM:616325;PMID:19949040;PMID:15496425;PMID:20371544)