- Bilateral tonic-clonic seizure (HP:0002069): A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase. Evidence: PCS. Frequency: 4/33. (PMID:23933820)
- Delayed speech and language development (HP:0000750): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: PCS. Frequency: 18/36. (PMID:23933820)
- Short stature (HP:0004322): A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms). Evidence: PCS. Frequency: 3/7. (PMID:20890276)
- Pes cavus (HP:0001761): An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight). Evidence: PCS. Frequency: 1/8. (PMID:20890276)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 19/35. (PMID:23933820)
- 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: PCS. Frequency: 7/8. (PMID:20890276)
- Focal impaired awareness seizure (HP:0002384): Focal impaired awareness seizure (or focal seizure with impaired or lost awareness) is a type of focal-onset seizure characterized by some degree (which may be partial) of impairment of the person's awareness of themselves or their surroundings at any point during the seizure. Evidence: PCS. Frequency: 4/33. (PMID:23933820)
- Atonic seizure (HP:0010819): 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: 1/33. (PMID:23933820)
- 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: PCS. Frequency: 4/8. (PMID:20890276)
- Short nose (HP:0003196): Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip. Evidence: PCS. Frequency: 1/8. (PMID:20890276)
- 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: 4/6. (PMID:20890276)
- Aphasia (HP:0002381): An acquired language impairment of some or all of the abilities to produce or comprehend speech and to read or write. Evidence: PCS. Frequency: 9/72. (PMID:23933820)
- EEG with centrotemporal focal spike waves (HP:0012557): EEG with focal sharp transient waves in the centrotemporal region of the brain (also known as the central sulcus), i.e., focal sharp waves of a duration less than 80 msec followed by a slow wave. Evidence: PCS. Frequency: 21/39. (PMID:20890276;PMID:23933820)
- Continuous spike and waves during slow sleep (HP:0031491): Diffuse, bilateral and recently also unilateral or focal localization spike-wave occurring in slow sleep or non-rapid eye movement sleep. Evidence: PCS. Frequency: 33/69. (PMID:23933820)
- Small for gestational age (HP:0001518): Smaller than normal size according to sex and gestational age related norms, defined as a weight below the 10th percentile for the gestational age. Evidence: PCS. Frequency: 1/4. Onset: Congenital onset (HP:0003577). (PMID:20890276)
- Primary microcephaly (HP:0011451): Head circumference below 2 standard deviations below the mean for age and gender at birth. Evidence: PCS. Frequency: 1/3. Onset: Congenital onset (HP:0003577). (PMID:20890276)
- Autistic behavior (HP:0000729): 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: 1/36. (PMID:23933820)
- Typified by incomplete penetrance (HP:0003829): Description of conditions in which not all individuals with a given genotype exhibit the disease. Penetrance is the proportion that develop disease given a lifespan of 80 years. Evidence: PCS. (PMID:23933820)
- Speech apraxia (HP:0011098): A type of apraxia that is characterized by difficulty or inability to execute speech movements because of problems with coordination and motor problems, leading to incorrect articulation. An increase of errors with increasing word and phrase length may occur. Evidence: PCS. Frequency: 8/36. (PMID:23933820)
- Bilateral tonic-clonic seizure with focal onset (HP:0007334): A bilateral tonic-clonic seizure with focal onset is a focal-onset seizure which progresses into a bilateral tonic-clonic phase. Evidence: PCS. Frequency: 3/33. (PMID:23933820)
- Attention deficit hyperactivity disorder (HP:0007018): 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: 6/36. (PMID:23933820)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: PCS. Frequency: 1/8. Onset: Infantile onset (HP:0003593). (PMID:20890276)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: PCS. Frequency: 14/33. (PMID:23933820)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: PCS. Frequency: 4/33. (PMID:23933820)
- Autosomal dominant inheritance (HP:0000006): 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:20890276)
- Intellectual disability (HP:0001249): 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: 9/44. (PMID:20890276;PMID:23933820)
These phenotypes are associated with the disease early-onset epileptic encephalopathy and intellectual disability due to GRIN2A mutation (OMIM:245570).