After well-preparation of instruments, DNA collection procedure, and assessor's training in the first 6 months, we will recruit 40, 170, and 90 ASD families in the first, second, and third year of the project, respectively. The instruments include the ADI-R, ADOS, K-SADS-E, SCQ, SRS, and ABC for measuring autistic psychopathology; WISC-III, MSEL and PPVT for cognitive ability; CPT, CANTAB, and WCST for neuropsychological functioning, and MRI, MRS, and DSI for brain imaging study.