[The genetic diagnosis of children with mental retardation]

Progress in cytogenetics and in molecular genetics has made it possible to apply these techniques to many aspects of medicine, to discover the pathogenesis of illnesses previously of unknown aetiology and to improve diagnosis, prognosis and prevention. They are also used in the preclinical diagnosis of individuals at risk, to identify the carriers of many genetic conditions and in prenatal diagnosis. In the analysis of mental retardation in children they are extremely useful, since they permit very early diagnosis.