Turcot syndrome (TS) is characterized by the association of colonic polyps and central nervous system tumors. The relative risk of cerebral tumor in patients with ...AtlasofGeneticsandCytogeneticsinOncologyandHaematologyHome  Genes  Leukemias  SolidTumors  Cancer-Prone  DeepInsight  CaseReports  Journals  Portal  Teaching  XY12345678910111213141516171819202122NATurcotsyndromeWritten2005-08MariaCristinaDigilioMedicalGenetics,BambinoGesùHospital,PiazzaS.Onofrio4,00165ùRome,Italy(Note:forLinksprovidedbyAtlas:click) IdentityOthernamesMalignanttumorsofthecentralnervoussystemassociatedwithfamilialpolyposisofthecolonAtlas_Id10026GenesimplicatedinAPC  MLH1  MHS6  MSH2  PMS2  NoteTurcotsyndrome(TS)ischaracterizedbytheassociationofcolonicpolypsandcentralnervoussystemtumors.Therelativeriskofcerebraltumorinpatientswithfamilialadenomatouspolyposisisconsidered92timesmorethatfoundinthegeneralpopulation.Thepredominantbraintumorsaremedulloblastomaandgliomas.InheritanceBothautosomaldominantandautosomalrecessivemodesofinheritancehavebeendescribed,basedontheanalysisoffamilialsegregationofthediseaseandtheresultsofmolecularstudies.Nevertheless,consideringthelowpenetranceandrarityofTS,theinvolvementofamajorgeneinassociationwithasecondlocuscontainingamodifiergeneorofenvironmenmtalfactorshasbeensuggested.ClinicsNeoplasticriskCardinalfindingsinTSarecolonicpolypswithtendencytocolorectalcancerandmalignantcentralnervoussystemtumors.Colonicpolyps:ThreetypesofpolyposiscoliaredescribedtooccurinTS:1)Type1ischaracterizedbymultiplecolonicpolypsnumberingbetween20and100,someofwhichmayexceed3cmindiameter;2)Type2ischaracterizdbyasmallnumberofcolonicpolyps,usuallylessthan10;3)Type3ischaracterizedbynumeroussmallcolonicpolypssimilartothoseofclassicalfamilialpolyposyscoli.Basedonmolecularentities,twogroupscandifferentiated:theoneduetomutationintheAPCgene(seebelow),characterizedbycolonicpolyps,thesecondoneduetomutationsintheDNAmismatchrepair(MMR)genes(seebelow)andcharacterizedbycolorectaladenomaswithoutpolypo