Abstract
Pervasive Developmental Disorders (PDD) including autism spectrum disorders (ASD) are neurodevelopemntal disorders characterized by delays in the development of multiple basic functions including socialization, communication and repetitive behaviors. Twin and family studies have demonstrated that ASD is highly heritable neurodevelopmental disorders. There are several genetic methods to find the genes for ASD, such as ASD-related genetic syndrome, linkage study, association study, chromosomal abnormality, copy number variation, gene expression study and intermediate phenotype study. Recent advances in the genetics of ASD emphasize its etiological heterogeneity, with each genetic susceptibility locus accounting for only a small fraction of cases or having a small effect. More recently, several causal genes for ASD such as NLGN3/4, SHANK3, NRXN1, etc., has been identified by the application of achievement of recent scientific technology in genetics to ASD genetics. NRXN-NLGN-SHANK pathway is associated with synaptogenesis and imbalance between excitatory and inhibitory currents. Therefore, abnormal synaptic homeostasis is strongly suggested as a risk factor to ASD.
