Intellectual disability consists of incomplete mental development, which entails a limitation in general mental abilities, intellectual functioning, adaptive behavior and functional skills, compared to individuals of the same age, sex and sociocultural environment. These limitations can be observed in many areas, such as communication, self-care, self-governance, and functional academic skills, among others.
Intellectual disability may appear as an isolated trait (non-syndromic intellectual disability), or associated with facial dysmorphic features, other morphological anomalies, multisystem disorders, multiple neuropsychiatric and/or neurobehavioral problems, such as autism or epilepsy, or neuromuscular features, for example: ataxia, spastic paraplegia, sensory or motor neuropathy and muscular dystrophy (syndromic intellectual disability).