Asperger syndrome Rediscovered as a diagnosis in the 1980's, Asperger is at the high end of the autism spectrum. Individuals with Asperger syndrome may be very bright and capable, but may also have serious difficulties with social interaction, or have unusually low tolerance for loud noise, bright lights, crowds, etc.
Pervasive Developmental Disorder--Not Otherwise Specified (PDD-NOS).This term is used for children who meet most, but not all, of the criteria for autism. Children with this disorder have basically the same pattern of strengths and weaknesses as children with autism, and benefit from the same interventions. It's important to note that PDD-NOS does NOT mean high or low functioning -- so individuals with this diagnosis may be very different from one another.
Childhood disintegrative disorder.Some time after their second birthdays, children with this very rare disorder begin to lose many of their abilities.
Rett disorder (also called Rett syndrome).This rare disorder only affects girls. Like childhood disintegrative disorder, it leads to profound disability and is extremely rare.