(developmental disorder) A disorder diagnosed in childhood that is marked by either physical or mental impairment or both, which in turn affects the child from achieving age related developmental milestones.

Developmental disabilities are severe, long-term problems. They may be physical, such as blindness. They may affect mental ability, such as learning disabilities. Or the problem can be both physical and mental, such as Down syndrome. The problems are usually life-long, and can affect everyday living. There are many causes of developmental disabilities, including Genetic or chromosome abnormalities. These cause conditions such as Down syndrome and Rett syndrome.; Prenatal exposure to substances. For example, drinking alcohol when pregnant can cause fetal alcohol spectrum disorders.; Certain infections in pregnancy; Preterm birth. Often there is no cure, but treatment can help the symptoms. Treatments include physical, speech, and occupational therapy. Special education classes and psychological counseling can also help. NIH: National Institute of Child Health and Human Development

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)

Developmental disability, any of multiple conditions that emerge from anomalies in human development. The essential feature of a developmental disability is onset prior to adulthood and the need for lifelong support. Examples of conditions commonly encompassed under the term developmental...