Autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting up to 1% of the population. Over the past few years, large-scale genomic studies have identified hundreds of genetic loci associated with liability to ASD. It is now time to translate these genetic discoveries into functional studies that can help us understand convergences and divergences across risk genes, and build pre-clinical cell and animal models. In this seminar, I will discuss some of the most recent findings on the genetic risk architecture of ASD. I will then expand on our work on biomarkers discovery and neurodevelopmental analyses in two rare genetic conditions associated with ASD: ADNP and DDX3X syndrome.