Differential development of autistic symptoms in a pair of fraternal twins.

The following case study reports the differential development of autistic symptoms over a 9-year period in a pair of fraternal twins. Neither of the twins developed normally. Evaluations revealed that although the older (male) twin showed some early signs of pathology and suffered from frequent illnesses, he ultimately has developed more normally than his sister, who likely sustained brain damage as a result of perinatal anoxia. Significant improvements has occurred in both cases. Diagnostic, etiological, and treatment implications are discussed.