Large-scale genomic analyses have identified genetic variants with a causal relationship to autism. These variants provide a starting point from which we can explore the etiological mechanisms between genotype and phenotype, including the neurological mechanisms, developmental changes, and cell types involved in autism. This panel describes several approaches to developing this genetic foundation and leveraging it to understand autism biology and phenotype. Parallel genetic approaches and consistent gene discovery methods in autism and developmental delay help distinguish genes shared between these disorders from those with more specific roles. Integrating new autism data into this gene discovery approach, alongside population-level allele frequencies, refines and expands the autism gene list. Whole genome sequencing data allows us to also investigate the role of rare noncoding variation in autism, potentially increasing the resolution to detect specific cell types, brain regions, and developmental stages involved in autism risk. Finally, integrating whole genome sequencing with RNA expression data in the developing human brain provides a complementary approach to identify the critical processes and genomic regions involved in brain development and assess how these intersect with known ASD risk factors such as disruptive variation, expression changes, and sex differences.