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).

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.

An atypical absence seizure is a type of generalized non-motor (absence) seizure characterized by interruption of ongoing activities and reduced responsiveness. In comparison to a typical absence seizure, changes in tone may be more pronounced, onset and/or cessation may be less abrupt, and the duration of the ictus and post-ictal recovery may be longer. Although not always available, an EEG often demonstrates slow (<3 Hz), irregular, generalized spike-wave activity.

Episodic bouts of involuntary movements with dystonic, choreic, ballistic movements, or a combination thereof. There is no loss of consciousness during the attacks.

An abnormality of the cerebral white matter.

An abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG) and being identified at multiple locations (foci).

Myoclonic absence seizure is a type of generalized non-motor (absence) seizure characterized by an interruption of ongoing activities, a blank stare and rhythmic three-per-second myoclonic movements, causing ratcheting abduction of the upper limbs leading to progressive arm elevation, and associated with 3 Hz generalized spike-wave discharges on the electroencephalogram. Duration is typically 10-60 s. Whilst impairment of consciousness may not be obvious the ILAE classified this seizure as a generalized non-motor seizure in 2017.

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.

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