- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- 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: Very frequent (HP:0040281). (ORPHA:3207)
- Micrognathia (HP:0000347): Developmental hypoplasia of the mandible. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Wide nasal bridge (HP:0000431): Increased breadth of the nasal bridge (and with it, the nasal root). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Downslanted palpebral fissures (HP:0000494): The palpebral fissure inclination is more than two standard deviations below the mean. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3207)
- Synophrys (HP:0000664): Meeting of the medial eyebrows in the midline. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3207)
- Adducted thumb (HP:0001181): In the resting position, the tip of the thumb is on, or near, the palm, close to the base of the fourth or fifth finger. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3207)
- 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: Very frequent (HP:0040281). (ORPHA:3207)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Frontal bossing (HP:0002007): Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Ventriculomegaly (HP:0002119): An increase in size of the ventricular system of the brain. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3207)
- Cerebral cortical atrophy (HP:0002120): Atrophy of the cortex of the cerebrum. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Aplasia/Hypoplasia of the cerebellum (HP:0007360). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3207)
- Aplasia/Hypoplasia of the corpus callosum (HP:0007370): Absence or underdevelopment of the corpus callosum. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
- Cerebral white matter hypoplasia (HP:0012430): Underdevelopment of the cerebral white matter. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:3207)
These phenotypes are associated with the disease White matter hypoplasia-corpus callosum agenesis-intellectual disability syndrome (ORPHA:3207).