Conjoined twins or Siamese twins are identical twins joined in utero. A very rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births ...ConjoinedtwinsFromWikipedia,thefreeencyclopediaJumptonavigationJumptosearch"Siamesetwins"redirectshere.Forotheruses,seeSiamesetwins(disambiguation).MedicalconditionConjoinedtwinsOthernamesSiamesetwinsX-rayofconjoinedtwins,Cephalothoracopagus.SpecialtyMedicalgenetics ConjoinedtwinsorSiamesetwinsareidenticaltwins[1]joinedinutero.Averyrarephenomenon,theoccurrenceisestimatedtorangefrom1in49,000birthsto1in189,000births,withasomewhathigherincidenceinSouthwestAsiaandAfrica.[2]Approximatelyhalfarestillborn,andanadditionalone-thirddiewithin24hours.Mostlivebirthsarefemale,witharatioof3:1.[2][3]Twocontradictingtheoriesexisttoexplaintheoriginsofconjoinedtwins.Themoregenerallyacceptedtheoryisfission,inwhichthefertilizedeggsplitspartially.[4]Theothertheory,nolongerbelievedtobethebasisofconjoinedtwinning,[4]isfusion,inwhichafertilizedeggcompletelyseparates,butstemcells(whichsearchforsimilarcells)findsimilarstemcellsontheothertwinandfusethetwinstogether.Conjoinedtwinsshareasinglecommonchorion,placenta,andamnioticsac,althoughthesecharacteristicsarenotexclusivetoconjoinedtwins,astherearesomemonozygoticbutnon-conjoinedtwinswhoalsosharethesestructuresinutero.[5]ChangandEngBunker(1811–1874)werebrothersborninSiamwhotraveledwidelyformanyyearsandwerelabeledasTheSiameseTwins.ChangandEngwerejoinedatthetorsobyabandofflesh,cartilage,andtheirfusedlivers.Inmoderntimes,theycouldhavebeeneasilyseparated.[6]Duetothebrothers'fameandtherarityofthecondition,theterm"Siamesetwins"cametobeusedasasynonymforconjoinedtwins.Contents1Causes2Types3Management3.1Separation4History5Notablepeople5.1Born19thcenturyandearlier5.2Born20thcentury5.3Born21stcentury6Infiction7Seealso8References9ExternallinksCauses[edit]Therearetwotheoriesaboutthedevelopmentofconjoinedtwins.Thefirstisthatasinglefertilizedeggdoesnotfullysplitduringtheprocessofformingidenticaltwins.Ifth