Cal. Prob. Code § 1420

“Developmental disability” means a disability which originates before an individual attains age 18, continues, or can be expected to continue, indefinitely, and constitutes a substantial handicap for such individual. As defined by the Director of Developmental Services, in consultation with the Superintendent of Public Instruction, this term includes mental retardation, cerebral palsy, epilepsy, and autism. This term also includes handicapping conditions found to be closely related to mental retardation or to require treatment similar to that required for mentally retarded individuals, but does not include other handicapping conditions that are solely physical in nature.