Flattening of the superior part of the acetabulum, which is a cup-shaped cavity at the base of the hipbone into which the ball-shaped head of the femur fits. The acetabular roof thereby appears horizontal rather than arched, as it normally does.

Disproportionately long fibulae.

Underdevelopment of one or more carpal bones.

An abnormality of the pinna, which is also referred to as the auricle or external ear.

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 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.

Severe mental retardation is defined as an intelligence quotient (IQ) in the range of 20-34.

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

Underdevelopment of the corpus callosum.

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

Subnormal intellectual functioning which originates during the developmental period. Intellectual disability, previously referred to as mental retardation, has been defined as an IQ score below 70.

Decreased size of the basal ganglia.

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.

Lack of stability of a joint.

An abnormality of skull shape characterized by a decreased anterior-posterior diameter. That is, a cephalic index greater than 81%. Alternatively, an apparently shortened anteroposterior dimension (length) of the head compared to width.

An osteochondrodysplasia that results in abnormalities of bone growth in the vertebral column, epiphysis, and metaphysis.

An abnormally short femoral neck (which is the process of bone, connecting the femoral head with the femoral shaft).

Decreased width of the wing (or ala) of the ilium (which is the large expanded portion which bounds the greater pelvis laterally).

Irregularity of the normally smooth surface of the metaphyses.

An irregular surface of the vertebral end plates, which are normally relatively smooth.

A flattened vertebral body shape with reduced distance between the vertebral endplates.

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

Reduction in the size or volume of epiphyses.

The presence of a splayed (i.e.,flared) metaphyseal segment of one or more long bones.

An excessive concavity of the posterior surface of one or more vertebral bodies.

Generalized muscular hypotonia (abnormally low muscle tone).

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

Interalar distance more than two standard deviations above the mean for age, i.e., an apparently increased width of the nasal base and alae.

Diminished length of the neck.

Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).

Forward prominence of the entire forehead, due to protrusion of the frontal bone.

Increased thickness of the lower lip, leading to a prominent appearance of the lower lip. The height of the vermilion of the lower lip in the midline is more than 2 SD above the mean. Alternatively, an apparently increased height of the vermilion of the lower lip in the frontal view (subjective).

Distance between the hairline (trichion) and the glabella (the most prominent point on the frontal bone above the root of the nose), in the midline, more than two SD below the mean. Alternatively, an apparently decreased distance between the hairline and the glabella.

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.

Hair on the neck extends more inferiorly than usual.

Abnormally increased hair growth referring to a male pattern of body hair (androgenic hair).

An abnormality of the skin.

Meeting of the medial eyebrows in the midline.

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

A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.