developmental disorder of mental health developmental disability true MONDO:0005287 https://www.ncbi.nlm.nih.gov/pubmed/20161538 Disorders in which there is a delay in development based on that expected for a given age level or stage of development. These impairments or disabilities originate before age 18, may be expected to continue indefinitely, and constitute a substantial impairment. Biological and nonbiological factors are involved in these disorders. (From American Psychiatric Glossary, 6th ed) EFO:0003852 MESH:D002658