A retrospective journal-based case study of an infant with autism and his twin.

This report describes the development of an infant who was later diagnosed with autism, and a direct comparison of his development to that of his twin, from a prenatal period through the age of 4 years, through the examination of personal journals and medical records kept by the mother of the twins. Examination of these journals revealed several differences in development between the twins, some as early as 6 months of age. In the first year of life, the infants already differed in language development, social development, sleep patterns, and sensitivity to pain. This rare opportunity to view early autistic development gives direction to developmental theories of autism and clinically useful cues to early signs of autism.