- 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: PCS. Frequency: 1/2. (PMID:33772159)
- Poor head control (HP:0002421): Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months. Evidence: PCS. Frequency: 6/6. (PMID:33772159;PMID:28540413)
- Peripheral axonal neuropathy (HP:0003477): An abnormality characterized by disruption of the normal functioning of peripheral axons. Evidence: PCS. Frequency: 2/6. (PMID:33772159;PMID:28540413)
- 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:617519)
- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 2/5. (PMID:33772159)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: IEA. Frequency: Very rare (HP:0040284). (OMIM:617519)
- Distal amyotrophy (HP:0003693): Muscular atrophy affecting muscles in the distal portions of the extremities. Evidence: PCS. Frequency: 4/5. (PMID:33772159)
- Absent brainstem auditory responses (HP:0004463): Lack of measurable response to stimulation of auditory evoked potentials. Evidence: PCS. Frequency: 1/2. (PMID:33772159)
- 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:28540413)
- Gastroesophageal reflux (HP:0002020): A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter. Evidence: PCS. Frequency: 3/3. (PMID:33772159)
- Distal muscle weakness (HP:0002460): Reduced strength of the musculature of the distal extremities. Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- Ankle contracture (HP:0034677). Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- 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: 1/1. (PMID:28540413)
- Severe intellectual disability (HP:0010864): Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Abnormal circulating creatine kinase activity (HP:0040081): Any deviation from the normal activity of creatine kinase in the blood circulation. Evidence: PCS. Frequency: 0/1. (PMID:28540413)
- Cerebral visual impairment (HP:0100704): A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye. Evidence: IEA. (OMIM:617519)
- Demyelinating motor neuropathy (HP:0007220): Demyelination of peripheral motor nerves. Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- Motor axonal neuropathy (HP:0007002): Progressive impairment of function of motor axons with muscle weakness, atrophy, and cramps. The deficits are length-dependent, meaning that muscles innervated by the longest nerves are affected first, so that for instance the arms are affected at a later age than the onset of deficits involving the lower leg. Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- 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: PCS. Frequency: 5/6. (PMID:33772159;PMID:28540413)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 4/6. (PMID:33772159;PMID:28540413)
- Generalized amyotrophy (HP:0003700): Generalized (diffuse, unlocalized) amyotrophy (muscle atrophy) affecting multiple muscles. Evidence: PCS. Frequency: 5/6. (PMID:33772159;PMID:28540413)
- Demyelinating peripheral neuropathy (HP:0007108): Demyelinating neuropathy is characterized by slow nerve conduction velocities with reduced amplitudes of sensory/motor nerve conduction and prolonged distal latencies. Evidence: PCS. Frequency: 0/5. (PMID:33772159)
- Type 1 muscle fiber atrophy (HP:0011807): Atrophy (wasting) affecting primary type 1 muscle fibers. This feature in general can only be observed on muscle biopsy. Evidence: PCS. Frequency: 3/3. (PMID:33772159;PMID:28540413)
- Myopathic facies (HP:0002058): A facial appearance characteristic of myopathic conditions. The face appears expressionless with sunken cheeks, bilateral ptosis, and inability to elevate the corners of the mouth, due to muscle weakness. Evidence: PCS. Frequency: 6/6. (PMID:33772159;PMID:28540413)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 3/6. (PMID:33772159;PMID:28540413)
- EEG abnormality (HP:0002353): Abnormality observed by electroencephalogram (EEG), which is used to record of the brain's spontaneous electrical activity from multiple electrodes placed on the scalp. Evidence: PCS. Frequency: 2/2. (PMID:33772159)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Choreoathetosis (HP:0001266): Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements). Evidence: PCS. Frequency: 1/5. (PMID:33772159)
- 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: 6/6. (PMID:33772159;PMID:28540413)
- Poor suck (HP:0002033): An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed. Evidence: PCS. Frequency: 6/6. (PMID:33772159;PMID:28540413)
- Recurrent infections due to aspiration (HP:0004891): Increased susceptibility to infections due to aspiration, as manifested by recurrent episodes of infections due to aspiration. Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: IEA. (OMIM:617519)
- Areflexia (HP:0001284): Absence of neurologic reflexes such as the knee-jerk reaction. Evidence: PCS. Frequency: 5/6. (PMID:33772159;PMID:28540413)
- Delayed gross motor development (HP:0002194): A type of motor delay characterized by a delay in acquiring the ability to control the large muscles of the body for walking, running, sitting, and crawling. Evidence: PCS. Frequency: 5/5. (PMID:33772159)
- Severe global developmental delay (HP:0011344): A severe delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. Frequency: 1/1. (PMID:28540413)
- Gastrostomy tube feeding in infancy (HP:0011471): Feeding problem necessitating gastrostomy tube feeding. Evidence: PCS. Frequency: 4/5. Onset: Infantile onset (HP:0003593). (PMID:33772159)
- Sensorineural hearing impairment (HP:0000407): A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve. Evidence: PCS. Frequency: 2/5. (PMID:33772159)
- 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:33772159)
- Neonatal hypotonia (HP:0001319): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period. Evidence: PCS. Frequency: 5/5. Onset: Neonatal onset (HP:0003623). (PMID:33772159)
- Ankle flexion contracture (HP:0006466). Evidence: PCS. Frequency: 2/5. (PMID:33772159)
- Horizontal nystagmus (HP:0000666): Nystagmus consisting of horizontal to-and-fro eye movements. Evidence: PCS. Frequency: 2/5. (PMID:33772159)
- Abnormal cerebral white matter morphology (HP:0002500): An abnormality of the cerebral white matter. Evidence: PCS. Frequency: 1/3. (PMID:33772159)
These phenotypes are associated with the disease neurodevelopmental disorder with hypotonia, neuropathy, and deafness (OMIM:617519).