De novo mutations in protein-coding genes are a well-established cause of developmental disorders(1). However, genes known to be associated with developmental disorders account for only a minority of the observed excess of such de novo mutations(1,2). Here, to identify previously undescribed genes associated with developmental disorders, we integrate healthcare and research exome-sequence data from 31,058 parent-offspring trios of individuals with developmental disorders, and develop a simulation-based statistical test to identify gene-specific enrichment of de novo mutations. We identified 285 genes that were significantly associated with developmental disorders, including 28 that had not previously been robustly associated with developmen...