- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 2/4. (PMID:28250456)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 3/4. (PMID:28250456)
- 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: 3/4. (PMID:28250456)
- Abnormality of the anterior commissure (HP:0030301): An anomaly of the anterior commissure, a bundle of nerve fibers that connect the two cerebral hemispheres across the midline. The anterior commissure plays a role in pain sensation and contains decussating fibers from the olfactory tracts. Evidence: PCS. Frequency: 3/3. (PMID:28250456)
- Horizontal supranuclear gaze palsy (HP:0007817): A supranuclear gaze palsy is an inability to look in a horizontal direction as a result of cerebral impairment. There is a loss of the voluntary aspect of eye movements, but, as the brainstem is still intact, all the reflex conjugate eye movements are normal. Evidence: PCS. Frequency: 3/4. (PMID:28250456)
- 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: 1/4. (PMID:28250456)
- Agenesis of corpus callosum (HP:0001274): Absence of the corpus callosum as a result of the failure of the corpus callosum to develop, which can be the result of a failure in any one of the multiple steps of callosal development including cellular proliferation and migration, axonal growth or glial patterning at the midline. Evidence: PCS. Frequency: 4/4. (PMID:28250456)
- 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: 4/4. (PMID:28250456)
- 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: 2/4. (PMID:28250456)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/4. (PMID:28250456)
- Fusion of the left and right thalami (HP:0010664): A developmental defect characterized by fusion of the left and right halves of the thalamus. Evidence: PCS. Frequency: 2/3. (PMID:28250456)
- Absent hippocampal commissure (HP:0033646): Absence of the fibers that connect the contralateral hippocampi via the crura of the fornix and run beneath the posterior portion of the corpus callosum. Evidence: PCS. Frequency: 3/3. (PMID:28250456)
- Midline brainstem cleft (HP:0033645): A developmental defect characterized by an abnormal cleft (V-shaped indentation of the stalklike part of the brain consisting of the medulla oblongata, the midbrain, and the pons. Evidence: PCS. Frequency: 3/3. (PMID:28250456)
- Interhemispheric cyst (HP:0032327): Cystic collection (sac-like, fluid containing pocket of membranous tissue) located in the interhemispheric fissure, with or without communication with the ventricular system. Evidence: PCS. Frequency: 2/4. (PMID:28250456)
- Hypoplasia of the pons (HP:0012110): Underdevelopment of the pons. Evidence: PCS. Frequency: 3/3. (PMID:28250456)
- Fetal onset (HP:0011461): Onset prior to birth but after 8 weeks of embryonic development (corresponding to a gestational age of 10 weeks). Evidence: PCS. Frequency: 1/4. (PMID:28250456)
- 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:28250456)
- Hydrocephalus (HP:0000238): Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation. Evidence: PCS. Frequency: 1/4. (PMID:28250456)
- Unsteady gait (HP:0002317). Evidence: PCS. Frequency: 1/4. (PMID:28250456)
- Bimanual synkinesia (HP:0001335): Involuntary movements of one hand that accompany and mirror intentional movements of the opposite hand. Evidence: PCS. Frequency: 2/3. (PMID:28250456)
- Hemiparesis (HP:0001269): Loss of strength in the arm, leg, and sometimes face on one side of the body. Hemiplegia refers to a complete loss of strength, whereas hemiparesis refers to an incomplete loss of strength. Evidence: PCS. Frequency: 1/4. (PMID:28250456)
- 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: 3/4. (PMID:28250456)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 1/4. (PMID:28250456)
These phenotypes are associated with the disease gaze palsy, familial horizontal, with progressive scoliosis, 2 (OMIM:617542).