Illinois Statutes Chapter 755. Estates § 5/11a-1. “Developmental disability”, “intellectual disability”, and “related condition” defined

(1) is attributable to cerebral palsy, epilepsy, or any other condition, other than mental illness, found to be closely related to an intellectual disability because that condition results in impairment of general intellectual functioning or adaptive behavior similar to that of individuals with an intellectual disability, and requires treatment or services similar to those required for those individuals. For purposes of this Act, autism is considered a related condition;

(2) is manifested before the individual reaches age 22;

(3) is likely to continue indefinitely; and

(4) results in substantial functional limitation in 3 or more of the following areas of major life activity: self-care, language, learning, mobility, self-direction, and capacity for independent living.