- Juvenile onset (HP:0003621, a Human Phenotype Ontology term): Onset of signs or symptoms of disease between the age of 5 and 15 years. Evidence: PCS. Frequency: 1/10. (PMID:25865495)
- Scoliosis (HP:0002650, a Human Phenotype Ontology term): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 1/10. (PMID:25865495)
- Delayed CNS myelination (HP:0002188, a Human Phenotype Ontology term): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 1/10. (PMID:25865495)
- Eyelid myoclonus (HP:0025097, a Human Phenotype Ontology term): Marked, involuntary jerking of the eyelids. Evidence: PCS. Frequency: 5/8. (PMID:25865495)
- Generalized non-motor (absence) seizure (HP:0002121, a Human Phenotype Ontology term): A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features. Evidence: PCS. Frequency: 8/9. (PMID:25865495)
- Atonic seizure (HP:0010819, a Human Phenotype Ontology term): Atonic seizure is a type of motor seizure characterized by a sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic event lasting about 1 to 2 seconds, involving head, trunk, jaw, or limb musculature. Evidence: PCS. Frequency: 5/8. (PMID:25865495)
- Global developmental delay (HP:0001263, a Human Phenotype Ontology term): 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: PCS. Frequency: 8/9. (PMID:25865495)
- Hypotonia (HP:0001252, a Human Phenotype Ontology term): 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: 1/10. (PMID:25865495)
- Ataxia (HP:0001251, a Human Phenotype Ontology term): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: PCS. Frequency: 1/10. (PMID:25865495)
- Myoclonic seizure (HP:0032794, a Human Phenotype Ontology term): A myoclonic seizure is a type of motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: PCS. Frequency: 2/9. (PMID:25865495)
- Childhood onset (HP:0011463, a Human Phenotype Ontology term): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 9/10. (PMID:25865495)
- Autistic behavior (HP:0000729, a Human Phenotype Ontology term): Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior. Evidence: PCS. Frequency: 7/10. (PMID:25865495)
- Generalized myoclonic-atonic seizure (HP:0011170, a Human Phenotype Ontology term): A generalized myoclonic-atonic seizure is a type of generalized motor seizure characterized by a myoclonic jerk followed by an atonic motor component. Evidence: PCS. Frequency: 8/8. (PMID:25865495)
- Attention deficit hyperactivity disorder (HP:0007018, a Human Phenotype Ontology term): Attention deficit hyperactivity disorder (ADHD) manifests at age 2-3 years or by first grade at the latest. The main symptoms are distractibility, impulsivity, hyperactivity, and often trouble organizing tasks and projects, difficulty going to sleep, and social problems from being aggressive, loud, or impatient. Evidence: PCS. Frequency: 2/10. (PMID:25865495)
- Tremor (HP:0001337, a Human Phenotype Ontology term): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: PCS. Frequency: 2/10. (PMID:25865495)
- Autosomal dominant inheritance (HP:0000006, a Human Phenotype Ontology term): 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 heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:25865495)
- Intellectual disability (HP:0001249, a Human Phenotype Ontology term): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: PCS. Frequency: 10/10. (PMID:25865495)
These phenotypes are associated with the disease epilepsy with myoclonic atonic seizures (OMIM:616421, an entry in Online Mendelian Inheritance in Man).