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).

A deficiency or slowing down of growth pre- and postnatally.

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

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).

A movement disorder which consists of effects including diminished voluntary movements and the presence of involuntary movements.

Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum.

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.

This term describes abnormality of the white matter of the cerebrum resulting from damage to the myelin sheaths of nerve cells.

Weakness of all four limbs.

Underdevelopment of the corpus callosum.

An abnormality of the auditory evoked potentials, which are used to trace the signal generated by a sound, from the cochlear nerve, through the lateral lemniscus, to the medial geniculate nucleus, and to the cortex.

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.

Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.

Delayed myelination in the central nervous system.

An increase in size of the anatomic space between the arachnoid membrane and pia mater in the region surrounding the cerebellum.

Reduced amount of myelin in the central nervous system resulting from defective myelinogenesis.

Partial or complete wasting (loss) of brain tissue that was once present.

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.

The presence of an abnormal lateral curvature of the spine.

A disorder of bone growth affecting the vertebrae and the ends of the long bones (epiphyses).

A decreased rate of skeletal maturation. Delayed skeletal maturation can be diagnosed on the basis of an estimation of the bone age from radiographs of specific bones in the human body.

An alteration of the normally smooth contour of the epiphysis leading to an irregular appearance.

Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.

Exaggerated concavity of the anterior or posterior surface of the vertebral body, i.e., the upper and lower vertebral endplates are hollowed inward.

Separation of the odontoid process from the body of the axis.

Distance between the oral commissures more than 2 SD above the mean. Alternatively, an apparently increased width of the oral aperture (subjective).

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Absence of fine and sharp appearance of brows, nose, lips, mouth, and chin, usually because of rounded and heavy features or thickened skin with or without thickening of subcutaneous and bony tissues.

Meeting of the medial eyebrows in the midline.

A form of strabismus with one or both eyes deviated outward.

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

A nonspecific term denoting degeneration of the retinal pigment epithelium and/or retinal photoreceptor cells.

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

A severe form of myopia with greater than -6.00 diopters.

Well-demarcated area(s) of partial or complete depigmentation in the macula, reflecting atrophy of the retinal pigment epithelium with associated retinal photoreceptor loss.

A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression.

Sharply demarcated area of partial or complete depigmentation of the fundus reflecting atrophy of the retinal pigment epithelium with associated retinal photoreceptor loss. The margins of the de-pigmented area are usually scalloped and the large choroidal vessels are visible through the atrophic retinal pigment epithelium.

A macular coloboma is an area of 2-6 disk diameters in which there is total or considerable chorioretinal maldevelopment, often with extasia of the underlying sclera which produces the white appearance visible ophthalmoscopically (summary by Phillips, 1970).

Lack of any response to stimulation upon electroretinography.

A severe form of hypermetropia with over +5.00 diopters.

Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.