<prompt> Mental retardation is not seen in -Downs syndromeCretinismHypopituitarismBirth asphyxia  <response>: Prenatal factors1. Metabolici Aminoaciduria-phenylketonuria, homocystinemia, histidinemia, organic aciduriaii Galactosemiaiii MucopolysaccharidosisivInherited degenerative disorders of the central nervous system2. Chromosomal disorders. Downs syndrome, Fragile X syndrome, Klinefelter3. Environment and nutrition gaps, iodine deficiency4. Neuroectodermal dysplasia. Tuberous sclerosis.5. Developmental defects. Microcephaly, craniostenosis, cretinism, porencephaly.6. Maternal factorsi Use of teratogenic drugs in the first trimesters of pregnancyii Infections such as rubella, toxoplasmosis, cytomegalic inclusion disease, herpes syphilis and HIV.iii Placental insufficiencyivToxemia of pregnancyv Antepartum hemorrhageviRadiation during pregnancyNatal factorsBirth injuries 3. Intracerebral hemorrhageHypoxic, ischemic encephalopathyPostnatal factorsInfections of central nervous system. Meningoencephalitis2. Head injuries3. Hypoxia4. Cerebrovascular. Thrombosis of cerebral vessels5. Post-vaccinal encephalopathies6. Kemicterus7. Hypoglycemia8. Malnutrition9. Child abuse 10. Autism 