Congenital vertical talus (CVT), also known as 'rocker-bottom foot' deformity, is a dislocation of the talonavicular joint characterized by vertical orientation of the talus with a rigid dorsal dislocation of the navicular, equinus deformity of the calcaneus, abduction deformity of the forefoot, and contracture of the soft tissues of the hind- and mid-foot. This condition is usually associated with multiple other congenital deformities and only rarely is an isolated deformity with familial occurrence (summary by Levinsohn et al., 2004). The condition is transmitted in an autosomal dominant pattern of inheritance, and sometimes shows incomplete penetrance and variable expressivity. There may be a broad spectrum of deformities, including flatfoot, talipes equinovarus (TEV or clubfoot), cavus foot, metatarsus adductus, and even hypoplasia of the tibia (summary by Dobbs et al., 2006).

An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.

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).

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

Chorea (Greek for 'dance') refers to widespread arrhythmic involuntary movements of a forcible, jerky and restless fashion. It is a random-appearing sequence of one or more discrete involuntary movements or movement fragments. Movements appear random because of variability in timing, duration or location. Each movement may have a distinct start and end. However, movements may be strung together and thus may appear to flow randomly from one muscle group to another. Chorea can involve the trunk, neck, face, tongue, and extremities.

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

Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.

Syndromes which feature dyskinesias as a cardinal manifestation of the disease process. Included in this category are degenerative, hereditary, post-infectious, medication-induced, post-inflammatory, and post-traumatic conditions.

Absence of neurologic reflexes such as the knee-jerk reaction.

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

A condition in which epileptiform abnormalities are believed to contribute to the progressive disturbance in cerebral function. Epileptic encephalaopathy is characterized by (1) electrographic EEG paroxysmal activity that is often aggressive, (2) seizures that are usually multiform and intractable, (3) cognitive, behavioral and neurological deficits that may be relentless, and (4) sometimes early death.

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.

A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs.

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

A myoclonic seizure is a type of motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus.

Displacement of the femur from its normal location in the hip joint.

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

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

A focal dystonia that affects the muscles of the eyelids and brow, associated with involuntary recurrent spasm of both eyelids.

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