A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.

A type of Developmental delay characterized by a delay in acquiring motor skills.

A structural abnormality of the myelinated axons (white matter) located near the cerebral ventricles.

A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features.

A failure to achieve the ability to stand up at an appropriate developmental stage. Most children begin to walk alone at 11 to 15 months of age. On average, children can stand while holding on at the age of 9 to 10 months, can pull up to stand and walk with one hand being held at 12 months, and can stand alone and walk well at 18 months.

A disorder of muscle unrelated to impairment of innervation or neuromuscular junction.

An abnormality in which the nuclei of sarcomeres take on an abnormally central localization (or in which this feature is found in an increased proportion of muscle cells).

An abnormally high degree of muscle fiber size variation. This phenotypic feature can be observed upon muscle biopsy.

An increased CPK level between 4X and 50X above the upper normal level.