The presence of abnormally small extremities.

A slower than normal heart rate (in adults, slower than 60 beats per minute).

Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.

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

Encephalopathy is a term that means brain disease, damage, or malfunction. In general, encephalopathy is manifested by an altered mental state.

Underdevelopment of the corpus callosum.

Cerebral cysts, usually located in the wall of the caudate nucleus or in the caudothalamic groove. They are found in up to 5.2% of all neonates, using transfontanellar ultrasound in the first days of life.

A severe delay in the achievement of motor or mental milestones in the domains of development of a child.

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.

Abnormally decreased levels of glutamine in cerebrospinal fluid.

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.

A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.

The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers or toes cannot be extended to 180 degrees by either active or passive extension.

Generalized muscular hypotonia (abnormally low muscle tone).

Lack of breathing with no movement of the respiratory muscles and no exchange of air in the lungs. This term refers to a disposition to have recurrent episodes of apnea rather than to a single event.

An increased susceptibility to respiratory infections as manifested by a history of recurrent respiratory infections.

Respiratory difficulty as newborn.

Decreased amount of glutamine in the blood.

An increased concentration of ammonia in the blood.

Height of the vermilion of the medial part of the lip more than 2 SD below the mean, or apparently reduced height of the vermilion of the lip in the frontal view. The vermilion is the red part of the lips (and confusingly, the vermilion itself is also often referred to as being equivalent the lips).

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

Anteriorly-facing nostrils viewed with the head in the Frankfurt horizontal and the eyes of the observer level with the eyes of the subject. This gives the appearance of an upturned nose (upturned nasal tip).

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

Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.

Redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin.