Genetic screening to determine an etiologic diagnosis in children with mental retardation]

Background: Mental retardation or intellectual disability affects 2% of the general population, but in 60% to 70% of cases the renal cause of this retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak areas and providing a genetic counseling to the family. Aim: To search genetic diseases underlying intellectual disabilities of children attending a special education school. Material and methods: A clinical geneticist performed the history and physical examination in one hundred and three students aged between 5 and 24 years (51 males). A blood fragile X molecular genetic testing, and search for inborn errors of metabolism by tandem mass spectrometry. Results: This approach yielded an etiological diagnosis in as much as 29 patients. Three percent of them had a fragile X syndrome. Inborn errors of metabolism were not detected. Conclusions: This type of screening should be done always in children with intellectual disability to establish an etiological diagnosis (Rev Med Chile 2008; 136: 1542-51).