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

Abnormally increased size of the liver.

A chronic disorder of the liver in which liver tissue becomes scarred and is partially replaced by regenerative nodules and fibrotic tissue resulting in loss of liver function.

A disorder characterized by the inability of the liver to metabolize chemicals in the body. Causes include cirrhosis and drug-induced hepatotoxicity. Signs and symptoms include jaundice and encephalopathy. Laboratory test results reveal abnormal plasma levels of ammonia, bilirubin, lactic dehydrogenase, and alkaline phosphatase.

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

The presence of chronic diarrhea, which is usually taken to mean diarrhea that has persisted for over 4 weeks.

Recurrent infection of the gastrointestinal tract.

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 characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.

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

Underdevelopment of the corpus callosum.

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.

Complete lack of development of speech and language abilities.

A proneness to anger, i.e., a tendency to become easily bothered or annoyed.

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

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.

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

Abnormal increased size of the spleen.

Elevations of the levels of SGOT and SGPT in the serum. SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) are transaminases primarily found in the liver and heart and are released into the bloodstream as the result of liver or heart damage. SGOT and SGPT are used clinically mainly as markers of liver damage.

Abnormally increased serum levels of alkaline phosphatase activity.

Abnormal transferrin isoform profile consistent with a type II congenital disorder of glycosylation.

An abnormal morphology (form) of the face or its components.

Increased density of hairs, i.e., and elevated number of hairs per unit area.

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