The multidiscipinary care of patients with intellectual disability requires a structured and systematic etiological process. Today, advances in technology make it possible to perform diagnostic genetic analyzes that are highly contributive in this process. The CGH-array (Comparative Genomic Hybridization array) makes it possible to search for chromosomal anomalies with a very high level of resolution; high throughput sequencing can detect gene abnormalities on the whole exome or on a panel of genes. For the patient the detection of genetic anomalies aims to improve the quality of care; for related parties, genetic counseling is systematically offered.