- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Low-set ears (HP:0000369): Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Chorioretinal coloboma (HP:0000567): Absence of a region of the retina, retinal pigment epithelium, and choroid. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Cerebellar vermis hypoplasia (HP:0001320): Underdevelopment of the vermis of cerebellum. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Ventriculomegaly (HP:0002119): An increase in size of the ventricular system of the brain. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Abnormal brainstem morphology (HP:0002363): An anomaly of the brainstem. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Abnormal cerebral cortex morphology (HP:0002538): Any structural abnormality of the cerebral cortex. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Episodic tachypnea (HP:0002876): Episodes of very rapid breathing. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Apneic episodes in infancy (HP:0005949): Recurrent episodes of apnea occurring during infancy. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Floppy infant (HP:0008947): Floppiness/hypotonia is defined as reduced resistance to passive movement of joints. Physical examination of floppy/hypotonic infants shows head lag, lack of shoulder and elbow muscle contraction on traction response, inability to tighten the shoulder girdle muscles (or slipping through) when held under the axillae, scarf sign (when the arm is pulled to the opposite side, the arm wraps around the neck with the elbow crossing midline), hyperdorsiflexion of the feet, easy apposition of the thumb against the forearm, feet touching the cheek with ease and without discomfort, frog leg position, and inverted U sign on ventral suspension (head, arms, and legs hanging down without elbow or knee flexion and the trunk rounded in a dome shape). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Nasogastric tube feeding (HP:0040288): The condition of inability to eat normally treated by placement of a thin tube through the nose into the stomach that is then used to carry food. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:163961)
- Retrognathia (HP:0000278): An abnormality in which the mandible is mislocalised posteriorly. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Hypertelorism (HP:0000316): Interpupillary distance more than 2 SD above the mean (alternatively, the appearance of an increased interpupillary distance or widely spaced eyes). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Micrognathia (HP:0000347): Developmental hypoplasia of the mandible. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Posteriorly rotated ears (HP:0000358): A type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Areflexia (HP:0001284): Absence of neurologic reflexes such as the knee-jerk reaction. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Dandy-Walker malformation (HP:0001305): A congenital brain malformation typically characterized by incomplete formation of the cerebellar vermis, dilation of the fourth ventricle, and enlargement of the posterior fossa. In layman's terms, Dandy Walker malformation is a cyst in the cerebellum (typically symmetrical) that is involved with the fourth ventricle. This may interfere with the ability to drain cerebrospinal fluid from the brain, resulting in hydrocephalus. Dandy Walker cysts are formed during early embryonic development, while the brain forms. The cyst in the cerebellum typically has several blood vessels running through it connecting to the brain, thereby prohibiting surgical removal. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Frontal bossing (HP:0002007): Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Poor suck (HP:0002033): An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Meckel diverticulum (HP:0002245): Meckel's diverticulum is a congenital diverticulum located in the distal ileum. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Agenesis of cerebellar vermis (HP:0002335): Congenital absence of the vermis of cerebellum. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Supernumerary ribs (HP:0005815): The presence of more than 12 rib pairs. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Uncontrolled eye movements (HP:0007738). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Undetectable visual evoked potentials (HP:0007965). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
- Thick nasal alae (HP:0009928): Increase in bulk of the ala nasi. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:163961)
These phenotypes are associated with the disease X-linked cerebral-cerebellar-coloboma syndrome (ORPHA:163961).