Intense feelings of nervousness, tension, or panic often arise in response to interpersonal stresses. There is worry about the negative effects of past unpleasant experiences and future negative possibilities. Individuals may feel fearful, apprehensive, or threatened by uncertainty, and they may also have fears of falling apart or losing control.

Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will.

Moderate mental retardation is defined as an intelligence quotient (IQ) in the range of 35-49.

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.

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.

The presence of one or more obsessive-compulsive personality traits. Obsessions refer to persistent intrusive thoughts, and compulsions to intrusive behaviors, which the affected person experiences as involuntary, senseless, or repugnant.

Generalized muscular hypotonia (abnormally low muscle tone).

The palpebral fissure inclination is more than two standard deviations below the mean.

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).

Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border.

Facial contour, as viewed from the front, triangular in shape, with breadth at the temples and tapering to a narrow chin.

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

Increased height of the central portion of the eyebrow, forming a crescent, semicircular, or inverted U shape.

Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).