Excessive postnatal growth which may comprise increased weight, increased length, and/or increased head circumference.

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.

A decreased magnitude of the sensory perception of sound.

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.

Underdevelopment of the corpus callosum.

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.

Arnold-Chiari type I malformation refers to a relatively mild degree of herniation of the posteroinferior region of the cerebellum (the cerebellar tonsils) into the cervical canal with little or no displacement of the fourth ventricle. It is characterized by one or both pointed (not rounded) cerebellar tonsils that project 5 mm below the foramen magnum, measured by a line drawn from the basion to the opisthion (McRae Line)

Underdevelopment of the pons.

Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.

Developmental hypoplasia of the mandible.

An abnormality in which the mandible is mislocalised posteriorly.

Abnormally small dimension of the Maxilla. Usually creating a malocclusion or malalignment between the upper and lower teeth or resulting in a deficient amount of projection of the base of the nose and lower midface region.

The postnatal development of an abnormally large skull (macrocephaly).

Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation.

Head circumference below 2 standard deviations below the mean for age and gender.

An abnormally decreased sodium concentration in the blood.

Abnormal prominence of the chin related to increased length of the mandible.

The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.

The palpebral fissure inclination is more than two standard deviations below the mean.

Distance between the medial and lateral canthi is more than 2 SD below the mean for age (objective); or, apparently reduced length of the palpebral fissures.

Increase in width of the nasal tip.

Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective).

A marked tapering of the lower face to the chin.

Increased breadth of the nasal bridge (and with it, the nasal root).

Columella extending inferior to the level of the nasal base, when viewed from the side.

Increased height of the central portion of the eyebrow, forming a crescent, semicircular, or inverted U shape.

Increase in periorbital soft tissue.

Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).

Primary or spontaneous detachment of the retina occurs due to underlying ocular disease and often involves the vitreous as well as the retina. The precipitating event is formation of a retinal tear or hole, which permits fluid to accumulate under the sensory layers of the retina and creates an intraretinal cleavage that destroys the neurosensory process of visual reception. Vitreoretinal degeneration and tear formation are painless phenomena, and in most cases, significant vitreoretinal pathology is found only after detachment of the retina starts to cause loss of vision or visual field. Without surgical intervention, retinal detachment will almost inevitably lead to total blindness (summary by McNiel and McPherson, 1971).

A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule.

Dilatation of small blood vessels of the retina.

Underdevelopment of the optic nerve.