Intellectual disability (ID) moderate or severe affects about one child in 250, with 3000 to 4000 new cases each year. Chromosomal or molecular pathology causes are not identified in half of the cases by current techniques. Studies show that de novo mutations are common in many different genes. The "exome" approach by high-throughput sequencing (NGS) has emerged as the technique of choice for identifying and comparing the exome of the child to the parent. We wish to evaluate this approach and its contribution in the diagnostic management of 50 patients with DI seen in genetics in 6 CHU Great West. Genomics platform IBISA / Biogenouest will provide technological and bioinformatics support this project.