- Epicanthus (HP:0000286): A fold of skin starting above the medial aspect of the upper eyelid and arching downward to cover, pass in front of and lateral to the medial canthus. Evidence: PCS. Frequency: 2/6. (PMID:40455867)
- Mild intellectual disability (HP:0001256): Mild intellectual disability (ID) is defined as a type of ID characterized by mildly sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 50-69. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- Hearing impairment (HP:0000365): A decreased magnitude of the sensory perception of sound. Evidence: PCS. Frequency: 1/3. (PMID:40455867)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- 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: 1/5. (PMID:40455867)
- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: PCS. Frequency: 0/5. (PMID:40455867)
- 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: 5/5. (PMID:40455867)
- Ataxia (HP:0001251): 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: 0/5. (PMID:40455867)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 6/6. (PMID:40455867)
- Multifocal epileptiform discharges (HP:0010841): An abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG) and being identified at multiple locations (foci). Evidence: PCS. Frequency: 3/5. (PMID:40455867;PMID:41000458)
- Caesarean section (HP:0011410): Delivery of a fetus through surgical incisions made through the abdominal wall (laparotomy) and the uterine wall (hysterotomy). Evidence: PCS. Frequency: 1/4. (PMID:40455867)
- Appendicular hypotonia (HP:0012389): Muscular hypotonia of one or more limbs. Evidence: PCS. Frequency: 1/1. (PMID:41000458)
- Sparse eyebrow (HP:0045075): Decreased density/number of eyebrow hairs. Evidence: PCS. Frequency: 1/3. (PMID:40455867)
- Thin corpus callosum (HP:0033725): An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration). Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- EEG with focal epileptiform discharges (HP:0011185): EEG discharges recorded in particular areas of a localized (focal) abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG). Evidence: PCS. Frequency: 2/2. (PMID:40455867)
- Allergy (HP:0012393): An allergy is an immune response or reaction to substances that are usually not harmful. Evidence: PCS. Frequency: 0/3. (PMID:40455867)
- Autism (HP:0000717): Autism is a neurodevelopmental disorder characterized by impaired social interaction and communication, and by restricted and repetitive behavior. Autism begins in childhood. It is marked by the presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activity and interest. Manifestations of the disorder vary greatly depending on the developmental level and chronological age of the individual (DSM-IV). Evidence: PCS. Frequency: 0/6. (PMID:40455867)
- CNS hypomyelination (HP:0003429): Reduced amount of myelin in the central nervous system resulting from defective myelinogenesis. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- Delayed ability to sit (HP:0025336): A failure to achieve the ability to sit at an appropriate developmental stage. Most children sit with support at 6 months of age and sit steadily without support at 9 months of age. Evidence: PCS. Frequency: 5/5. (PMID:40455867)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: PCS. Frequency: 4/5. (PMID:40455867)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 1/1. (PMID:41000458)
- Bruxism (HP:0003763): Bruxism is characterized by the grinding of the teeth including the clenching of the jaw and typically occur during sleep. Evidence: PCS. Frequency: 1/5. (PMID:40455867)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: PCS. Frequency: 3/5. (PMID:40455867)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 0/1. (PMID:41000458)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 5/5. (PMID:40455867)
- Abnormality of eye movement (HP:0000496): An abnormality in voluntary or involuntary eye movements or their control. Evidence: PCS. Frequency: 0/5. (PMID:40455867)
- 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: 2/3. (PMID:40455867)
- Contractures of the large joints (HP:0005781). Evidence: PCS. Frequency: 0/3. (PMID:40455867)
- EEG with abnormally slow frequencies (HP:0011203): EEG with abnormally slow frequencies. Evidence: PCS. Frequency: 1/4. (PMID:40455867)
- Generalized clonic seizure (HP:0011169): Generalized clonic seizure is a type of generalized motor seizure characterized by sustained bilateral jerking, either symmetric or asymmetric, that is regularly repetitive and involves the same muscle groups. Evidence: PCS. Frequency: 1/1. (PMID:41000458)
- Dyskinesia (HP:0100660): A movement disorder which consists of effects including diminished voluntary movements and the presence of involuntary movements. Evidence: PCS. Frequency: 0/5. (PMID:40455867)
- Primary microcephaly (HP:0011451): Head circumference below 2 standard deviations below the mean for age and gender at birth. Evidence: PCS. Frequency: 1/1. (PMID:40455867)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 1/1. (PMID:40455867)
- 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:40455867)
- Macrotia (HP:0000400): Median longitudinal ear length greater than two standard deviations above the mean and median ear width greater than two standard deviations above the mean (objective); or, apparent increase in length and width of the pinna (subjective). Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- 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: 1/6. (PMID:40455867)
- Spasticity (HP:0001257): A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes. Evidence: PCS. Frequency: 4/4. (PMID:40455867)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: PCS. Frequency: 0/5. (PMID:40455867)
- Sudden death (HP:0001699): Rapid and unexpected death. Evidence: PCS. Frequency: 1/1. (PMID:40455867)
- Hypertonia (HP:0001276): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: PCS. Frequency: 0/1. (PMID:40455867)
- Glabellar hemangioma (HP:0001076). Evidence: PCS. Frequency: 1/3. (PMID:40455867)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. Frequency: 1/1. (PMID:40455867)
- Recurrent infections (HP:0002719): Increased susceptibility to infections as manifested by repeated bouts of infection. Evidence: PCS. Frequency: 0/3. (PMID:40455867)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: PCS. Frequency: 2/5. (PMID:40455867)
- Reduced eye contact (HP:0000817): A reduced frequency or duration of eye contact. Evidence: PCS. Frequency: 1/1. (PMID:41000458)
- Respiratory failure (HP:0002878): A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits. Evidence: PCS. Frequency: 3/3. (PMID:40455867)
- Ventriculomegaly (HP:0002119): An increase in size of the ventricular system of the brain. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 4/5. (PMID:40455867)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 2/6. (PMID:40455867;PMID:41000458)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 2/6. (PMID:40455867)
- Wide nasal bridge (HP:0000431): Increased breadth of the nasal bridge (and with it, the nasal root). Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- 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: 1/1. (PMID:40455867)
- Status epilepticus (HP:0002133): Status epilepticus is a type of prolonged seizure resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms which lead to abnormally prolonged seizures (after time point t1). It is a condition that can have long-term consequences (after time point t2), including neuronal death, neuronal injury, and alteration of neuronal networks, depending on the type and duration of seizures. Evidence: PCS. Frequency: 5/6. (PMID:40455867)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 0/3. (PMID:40455867)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 0/5. (PMID:40455867)
- Delayed ability to walk (HP:0031936): A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months. Evidence: PCS. Frequency: 1/1. (PMID:40455867)
- Inability to walk by childhood/adolescence (HP:0006915). Evidence: PCS. Frequency: 4/4. (PMID:40455867)
- Prominent metopic ridge (HP:0005487): Vertical bony ridge positioned in the midline of the forehead. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- Secondary microcephaly (HP:0005484): Head circumference which falls below 2 standard deviations below the mean for age and gender because of insufficient head growth after birth. Evidence: PCS. Frequency: 0/4. (PMID:40455867)
- Bilateral tonic-clonic seizure with generalized onset (HP:0025190): A bilateral tonic-clonic seizure with generalized onset is a type of bilateral tonic-clonic seizure characterized by generalized onset; these seizures rapidly engage networks in both hemispheres at the start of the seizure. Evidence: PCS. Frequency: 6/7. (PMID:40455867;PMID:41000458)
- Impairment of activities of daily living (HP:0031058): Difficulty in performing one or more activities normally performed every day, such as eating, bathing, dressing, grooming, work, homemaking, and leisure. Evidence: PCS. Frequency: 6/6. (PMID:40455867)
- 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:41000458)
- EEG with generalized epileptiform discharges (HP:0011198): EEG discharges recorded on the entire scalp typically seen in persons with epilepsy. Evidence: PCS. Frequency: 1/4. (PMID:40455867)
- 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: 1/1. (PMID:41000458)
- Dolichocephaly (HP:0000268): An abnormality of skull shape characterized by a increased anterior-posterior diameter, i.e., an increased antero-posterior dimension of the skull. Cephalic index less than 76%. Alternatively, an apparently increased antero-posterior length of the head compared to width. Often due to premature closure of the sagittal suture. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- Abnormal nerve conduction velocity (HP:0040129). Evidence: PCS. Frequency: 0/2. (PMID:40455867;PMID:41000458)
- Micrognathia (HP:0000347): Developmental hypoplasia of the mandible. Evidence: PCS. Frequency: 1/6. (PMID:40455867)
- EMG abnormality (HP:0003457): Abnormal results of investigations using electromyography (EMG). Evidence: PCS. Frequency: 0/1. (PMID:40455867)
These phenotypes are associated with the disease developmental and epileptic encephalopathy 121 (OMIM:621475).