The article reviews the recent advances in autism genetics, highlighting the identification of several autism susceptibility genes and the increased understanding of the role of de novo and inherited copy number variations. It discusses the use of systems biology approaches, such as array-based expression profiling, to gain insights into the genetic and phenotypic heterogeneity of autism spectrum disorders (ASDs). The authors emphasize the importance of multiple parallel approaches, including whole-genome and pathway-based association studies, dense resequencing, and large well-characterized patient cohorts, to advance the understanding of the genetic factors underlying ASDs. They also explore the complex genetic architecture of ASDs, where rare and common variants may contribute to disease risk and phenotypic presentation. The article further examines the neurobiological hypotheses and the role of synaptic dysfunction, abnormal brain connectivity, and other biological themes in ASDs. Finally, it discusses the challenges and future directions in ASD genetics, emphasizing the need for larger cohorts and the integration of genetic and phenotypic data to better understand the genetic and biological mechanisms underlying ASDs.The article reviews the recent advances in autism genetics, highlighting the identification of several autism susceptibility genes and the increased understanding of the role of de novo and inherited copy number variations. It discusses the use of systems biology approaches, such as array-based expression profiling, to gain insights into the genetic and phenotypic heterogeneity of autism spectrum disorders (ASDs). The authors emphasize the importance of multiple parallel approaches, including whole-genome and pathway-based association studies, dense resequencing, and large well-characterized patient cohorts, to advance the understanding of the genetic factors underlying ASDs. They also explore the complex genetic architecture of ASDs, where rare and common variants may contribute to disease risk and phenotypic presentation. The article further examines the neurobiological hypotheses and the role of synaptic dysfunction, abnormal brain connectivity, and other biological themes in ASDs. Finally, it discusses the challenges and future directions in ASD genetics, emphasizing the need for larger cohorts and the integration of genetic and phenotypic data to better understand the genetic and biological mechanisms underlying ASDs.