- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- 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: 1/2. (PMID:25845469)
- Profound intellectual disability (HP:0002187): Profound intellectual disability (ID) is defined as a type of ID characterized by profoundly sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) below 20. Evidence: PCS. Frequency: 3/3. (PMID:30847200;PMID:25845469)
- Sleep disturbance (HP:0002360): An abnormal pattern in the quality, quantity, or characteristics of sleep. Evidence: PCS. Frequency: 2/2. Onset: Infantile onset (HP:0003593). (PMID:25845469)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- 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: 1/2. (PMID:25845469)
- Hypoplasia of the pons (HP:0012110): Underdevelopment of the pons. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- Ventricular septal defect (HP:0001629): A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum. Evidence: PCS. Frequency: 1/2. Onset: Congenital onset (HP:0003577). (PMID:25845469)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/1. (PMID:30847200)
- Irritability (HP:0000737): An emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Evidence: PCS. Frequency: 2/2. Onset: Infantile onset (HP:0003593). (PMID:25845469)
- 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: 5/5. (PMID:21868677)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 1/6. (PMID:30847200;PMID:21868677)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- 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:30847200)
- 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:25845469)
- Expressive language delay (HP:0002474): A delay in the acquisition of the ability to use language to communicate needs, wishes, or thoughts. Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- 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: 1/2. (PMID:25845469)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: PCS. Frequency: 1/1. (PMID:30847200)
- 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: 2/2. Onset: Infantile onset (HP:0003593). (PMID:25845469)
- 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: 3/3. (PMID:30847200;PMID:25845469)
- Cerebral palsy (HP:0100021): Cerebral palsy describes a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to nonprogressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication, and behavior, by epilepsy, and by secondary musculoskeletal problems. Evidence: PCS. Frequency: 1/3. (PMID:30847200;PMID:25845469)
- Nonprogressive encephalopathy (HP:0007030). Evidence: PCS. Frequency: 2/2. (PMID:25845469)
- 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. Frequency: 20/20. (PMID:21868677;PMID:25845469)
- Atrial septal defect (HP:0001631): Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum. Evidence: PCS. Frequency: 1/2. Onset: Congenital onset (HP:0003577). (PMID:25845469)
- 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: 3/3. (PMID:30847200;PMID:25845469)
These phenotypes are associated with the disease intellectual disability, autosomal recessive 18 (OMIM:614249).