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).

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

A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.

A seizure is an intermittent abnormality of nervous system physiology characterised by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

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.

An exaggerated startle reaction in response to a sudden unexpected visual or acoustic stimulus, or a quick movement near the face.

An increase in size of the ventricular system of the brain.

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

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

A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.