- Conductive hearing impairment (HP:0000405): An abnormality of vibrational conductance of sound to the inner ear leading to impairment of sensory perception of sound. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1861)
- Depressed nasal ridge (HP:0000457): Lack of prominence of the nose resulting from a posteriorly-placed nasal ridge. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1861)
- Narrow chest (HP:0000774): Reduced width of the chest from side to side, associated with a reduced distance from the sternal notch to the tip of the shoulder. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1861)
- Abnormal metaphysis morphology (HP:0000944): An abnormality of one or more metaphysis, i.e., of the somewhat wider portion of a long bone that is adjacent to the epiphyseal growth plate and grows during childhood. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1861)
- 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:1861)
- 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:1861)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1861)
- 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: Frequent (HP:0040282). (ORPHA:1861)
- 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:1861)
- Communicating hydrocephalus (HP:0001334): A form of hydrocephalus in which there is no visible obstruction to the flow of the cerebrospinal fluid between the ventricles and subarachnoid space. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1861)
- Respiratory failure (HP:0002878): A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1861)
- 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:1861)
- Limb undergrowth (HP:0009826): Limb shortening because of underdevelopment of one or more bones of the extremities. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1861)
These phenotypes are associated with the disease Thoracic dysplasia-hydrocephalus syndrome (ORPHA:1861).