- Strabismus (HP:0000486): A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error. Evidence: PCS. Frequency: 3/7. (PMID:29267967)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 1/10. (PMID:29267967)
- Trigonocephaly (HP:0000243): Wedge-shaped, or triangular head, with the apex of the triangle at the midline of the forehead and the base of the triangle at the occiput. Evidence: PCS. Frequency: 1/10. (PMID:29267967)
- 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: 3/10. (PMID:29267967)
- Cerebral cortical atrophy (HP:0002120): Atrophy of the cortex of the cerebrum. Evidence: PCS. Frequency: 2/10. (PMID:29267967)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. (PMID:29267967)
- 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: 2/4. (PMID:29267967)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: PCS. Frequency: 2/9. (PMID:29267967)
- Reduced eye contact (HP:0000817): A reduced frequency or duration of eye contact. Evidence: PCS. Frequency: 2/9. (PMID:29267967)
- Aggressive behavior (HP:0000718): Behavior or an act aimed at harming a person, animal, or physical property (e.g., acts of physical violence; shouting, swearing, and using harsh language; slashing someone's tires). Evidence: PCS. Frequency: 3/7. (PMID:29267967)
- High palate (HP:0000218): Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective). Evidence: PCS. Frequency: 1/8. (PMID:29267967)
- Hyperactivity (HP:0000752): Hyperactivity is a condition characterized by constant and unusually high levels of activity, even in situations where it is deemed inappropriate. Evidence: PCS. Frequency: 3/7. (PMID:29267967)
- Retrognathia (HP:0000278): An abnormality in which the mandible is mislocalised posteriorly. Evidence: PCS. Frequency: 2/8. (PMID:29267967)
- Abnormal pinna morphology (HP:0000377): An abnormality of the pinna, which is also referred to as the auricle or external ear. Evidence: PCS. Frequency: 1/8. (PMID:29267967)
- 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: 10/10. (PMID:29267967)
- Frontal upsweep of hair (HP:0002236): Upward and/or sideward growth of anterior hair. Evidence: PCS. Frequency: 1/8. (PMID:29267967)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 3/4. (PMID:29267967)
- Bifid nasal tip (HP:0000456): A splitting of the nasal tip. Visually assessable vertical indentation, cleft, or depression of the nasal tip. Evidence: PCS. Frequency: 1/8. (PMID:29267967)
- Wide nasal bridge (HP:0000431): Increased breadth of the nasal bridge (and with it, the nasal root). Evidence: PCS. Frequency: 1/8. (PMID:29267967)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 3/10. (PMID:29267967)
- 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: 10/10. (PMID:29267967)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 1/10. (PMID:29267967)
- 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: 4/10. (PMID:29267967)
- 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: 10/10. (PMID:29267967)
- Delayed gross motor development (HP:0002194): A type of motor delay characterized by a delay in acquiring the ability to control the large muscles of the body for walking, running, sitting, and crawling. Evidence: PCS. Frequency: 6/6. (PMID:29267967)
- X-linked recessive inheritance (HP:0001419): A mode of inheritance that is observed for recessive traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked recessive disorders manifest in males (who have one copy of the X chromosome and are thus hemizygotes), but generally not in female heterozygotes who have one mutant and one normal allele. Evidence: PCS. (PMID:29267967)
- 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: 4/7. (PMID:29267967)
- High forehead (HP:0000348): An abnormally increased height of the forehead. Evidence: PCS. Frequency: 2/8. (PMID:29267967)
- Optic atrophy (HP:0000648): Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy. Evidence: PCS. Frequency: 1/9. (PMID:29267967)
- 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: 2/4. (PMID:29267967)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: PCS. Frequency: 2/4. (PMID:29267967)
These phenotypes are associated with the disease intellectual disability, X-linked 104 (OMIM:300983).