"Autism (OMIM 209850) and attention deficit/hyperactivity disorder (ADHD) (OMIM 143465) are severe neurodevelopmental disorders with a complex etiology, caused by the interaction of multiple susceptibility genes, environmental and epigenetic factors. Autism and ADHD are the most common developmental disabilities after mental retardation. Different genetic approaches have been used so far to identify the genetic factors underlying complex disorders including linkage studies, association studies, search for cytogenetic abnormalities or Copy Number Variants (CNVs) analysis. The results obtained through these methodologies in recent years indicate that complex diseases such as Autism or ADHD are likely to be caused by a combination of common variants and multiple rare variants at different loci. However, these efforts have resulted in a limited number of significant and replicated findings, that explain only a small part of the genetic contribution to these disorders. The GEVAD proposal (Rare and Common Genetic Variants analysis in ASD and ADHD) aim to identify the genetic factors involved in the susceptibility to Autism and ADHD. The proposal will take advantage of modern high-throughput DNA technologies and expert collaborations to carry out three main studies: 1) Case/Control association studies of SNPs located in miRNA genes and in miRNA-binding motifs of selected candidate genes for Autism and ADHD 2) Replication of rare Copy Number Variants (NRXN1, CNTNAP2,SHANK3, IMMP2L-DOCK4) in autism and exploration of these structural variants as susceptibility factors for ADHD 3) Exome mutation analysis of autistic patients. To our knowledge, this will be the first exome analysis performed in a complex disease. The results emerging from GEVAD will provide new insights into the genetic basis of ASD and ADHD and may point to potential therapeutic targets for these common neuropsychiatric disorders."