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18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease18疾病的產(chǎn)前診斷PrenatalDiagnosisofDiFurthermore,thepsychologicalstressonfamilieswithchildrenwithseriousgeneticdisordersisincalculable.Untilgenetherapybecomesapracticalreality,theonlyoptionavailableforthecontrolofgeneticdiseaseisprenataldiagnosis.Furthermore,thepsyc1.Indicationsforprenataldiagnosis

Theuseofprenataldiagnosisisdeterminedbybalancingtheriskofthebirthofanabnormalchildagainsttheriskofaninvestigativeprocedure.1.Indicationsforprenataldi

Thegeneralindicationsofprenataldiagnosisincludematernalageandtheresultsofnoninvasiveserumbiochemicalscreening.Thegeneralindicationsof

Specificindicationsincludeapositivefamilyhistoryandthebirthofapreviouschildaffectedbyaparticulargeneticdisease.Specificindicationsinclud2.Methodsforobtainingfetaltissuesforprenataldiagnosis

Toperformprenataldiagnosis,fetal-derivedtissuesmustfirstbeobtained.Allofthecommonlyusedmethodsthatyieldfetaltissuesareinvasive.

2.MethodsforobtainingfetalA.AmniocentesisAmniocentesisisthewithdrawalofamnioticfluidfromtheamnioticsacsurroundingthefetus.Forovertwodecadesthishasbeentheprimarytechniqueutilisedforthediagnosisoffetalgeneticdisorders.A.AmniocentesisTraditionallyamniocentesishasbeenperformedaround15to16weeksgestation.Atthistimetheuterusiseasilyaccessibletoatransabdominalapproach,andasufficientvolumeofamnioticfluid(approximately200ml)existstopermit20to30mltobewithdrawnsafely.TraditionallyamniocenAmniocentesisisnormallyperformedasanoutpatientfacility.Anultrasoundexaminationisnormallydoneimmediatelybeforetheproceduretoevaluatefetalnumberandviability,performfetalbiometricmeasurements,establishplacentallocation,andestimateamnioticfluidvolume.AmniocentesisisnormalAmniocentesisperformedconcurrentlywithultrasoundscanning.

AmniocentesisperformedconcurSafetyofamniocentesisAnyprocedurethatinvolvespassingadeviceintoanorgan,especiallythepregnantuterus,carrieswithitrisks;amniocentesisisnoexception.SafetyofamniocentesisAmniocentesisinvolvespotentialdangertobothmotherandfetus.Seriousmaternalrisksarequitelowbutincludeamnionitiswhichcanleadtofetalloss,haemorrhageorinjurytoanintra-abdominalviscusandleakageofamnioticfluid. AmniocentesisinvolvesFetalrisksincludespontaneousabortion,needlepunctureinjuries,placentalabruption,chorioamnionitis,pretermlabour,andamnioticbandformation.FetalrisksincludespSeveralcontrolledstudieshavebeendonetoevaluatetherisksofamniocentesis.Thedataindicatethattheriskofpregnancylossattributabletoamniocentesismaybeashighas0.5%.SeveralcontrolledstIngeneral,riskswilldependon(1)theexperienceoftheobstetricianperformingtheprocedure;(2)clinicalcharacteristicsofaparticularcase(e.g.,presenceorabsenceofbiochemicalmarkersoffetalabnormality);(3)thequalityofthehigh-resolutionultrasoundutilised.Ingeneral,riskswillEarlyamniocentesis

Withdevelopmentofhigherresolutionultrasoundequipment,somecentreshavebegunofferingamniocentesisbefore15weeksgestation,usuallybetween10and14weeks.Themajorityofprocedureshavebeenperformedduringthe13thand14thweeksofgestation.

EarlyamniocentesisThereisevidencethatearlyamniocentesisisassociatedwithahigherfetallossrateandamorefrequentoccurrenceofcertaincongenitalabnormalities.ThereisevidencethaB.Chorionicvillussampling

Chorionicvillussampling(CVS)istheonlytestedmethodforfirst-trimesterfetalgeneticdiagnosisthatiscurrentlyinclinicaluseandisusuallyperformedbetween9and11weeks.B.Chorionicvillussampling Theprocedureinvolvesthepassingofasamplinginstrumentintothechorion(developingplacenta).Agoodprocedureyieldsfrom10to25mgoftissuewhichisadequateforcytogenetic,enzymaticorDNAanalysis.TheprocedureinvolvesThemainadvantageofCVSoveramniocentesisistheapplicabilityofCVSearlieringestation.Thisresultsinconsiderablyreducedsocial,emotionalandpsychologicalstressforthecouple.ThemainadvantageofSafetyofCVS Maternalcomplicationsincludebleedingandinfection.FetallossfollowingCVShasbeenreportedtobearound2%.TherearealsoreportsoflimbreductiondefectsininfantsborntomotherswhohavehadCVSbetween56and66daysofgestation.SafetyofCVSC.Fetalbloodsampling(FBS) Fetalbloodcanbesafelyanddirectlysampledfromapproximately18weeksgestationonwards.FBScanbeusedforbothdiagnosticandtherapeuticpurposes.C.Fetalbloodsampling(FBS)

IndicationsforfetalbloodsamplingDiagnosticRapidkaryotypingFetalanomalyonultrasoundLateattendingpatientswhorequirefetalkaryotypingAlloimmunisationRhesusPlateletantigensFetalinfectionToxoplasmosisCytomegalovirusinfectionGeneticHaemoglobinopathiesMetabolicdisordersandenzymedeficienciesFetalwellbeingSevereintrauterinegrowthretardationTherapeuticTransfusionRedcellalloimmunisationTransplantationStemcells

FBSiscontraindicatedifthemotherissufferingfrominfectionsthatcanbetransmittedtothefetusbytheprocedure.ExamplesincludehumanimmunodeficiencyvirusandhepatitisBvirusinfection.FBSiscontraindicatedSafetyofFBSMaternalcomplicationsfromFBSareuncommonbutincludeamnionitis,infection,rhesussensitisationandtransplacentalhaemorrhage.SafetyofFBSFetallossratesfollowingFBShavebeenreportedtobeapproximately1%inseverallargeseries.Thepresenceofstructuralabnormalitiesorseveregrowthretardationofthefetusisassociatedwithamuchincreasedfetallossrate.FetallossratesfolloOtherfetalcomplicationsincludeinfection,prematureruptureofmembranes,haemorrhage,severebradycardiaandumbilicalcordthrombosis.OtherfetalcomplicatiD.FetalbiopsyAlthoughadvancesinmolecularandbiochemicalgeneticshavemadethediagnosisofmanyMendeliandisorderspossiblebyanalysisofamnioticfluidcellsorchorionicvilli,someconditionsstillrequiredirectanalysisoftissuesinwhichthedisorderismanifested.Tissueswhichhavebeensuccessfullybiopsiedincludefetalskin,liverandmuscle.D.FetalbiopsySafetyoffetalbiopsyDuetotherelativelysmallnumbersperformedindifferentcentres,noprecisefiguresforthesafetyoffetalbiopsyisavailable.Safetyoffetalbiopsy3.AnalyticalmethodsFollowingtheacquisitionoffetaltissues,thesematerialsarethensubjectedtoanalysisusingavarietyoftechniques.3.AnalyticalmethodsFA.Cellcultureandconventionalcytogenetics

ThesearethemostcommonlyusedmethodsforthediagnosisofchromosomalaneuploidiessuchasDownsyndrome.A.CellcultureandconventionB.MolecularcytogeneticsusingFISHFISHinvolvesthehybridizationofDNAprobesrepresentingaspecificchromosomeorchromosomalregiontotargetDNAsuchasmetaphasechromosomesorinterphasenuclei,wheretheprobebindstohomologoussequencesinthecell.B.MolecularcytogeneticsusinUsingFISH,severalgroupshavedemonstratedthattrisomiessuchastrisomy21andtrisomy18canbedetectedinunculturedinterphasenucleiasthreepositivehybridisationsignalsratherthanthenormaltwo.UsingFISH,severalgroThemainadvantageisspeed:thusresultsareavailablein24to48hourscomparedwiththe10to14daysmoretypicalofstandardculture-basedcytogeneticanalysis.Thistypeoftechnologycanbeappliedtofetalmaterialsobtainedfollowingamniocentesis,CVSorfetalbloodsampling.ThemainadvantageisspC.DNA-basedtechniquesThemainadvantageofDNA-basedtechniquesisthatanynucleatedfetalcellcanbeused.Techniqueswhichareusedincludethepolymerasechainreaction(PCR)andSouthernblotting.

C.DNA-basedtechniquesPCR-basedtechniquesallowarapiddiagnosistobemadeinseveralhours.Thesemethodscanbeusedfordirectmutationdetectionorlinkageanalysis.Thelattertypeofanalysisisneededwhentheexactmutationorgenecausingthediseaseisnotknown.PCR-basedtechniquesa最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件GeneticdiagnosisisthencarriedoutbyanalysingDNAsequenceswithinthegeneitselforDNAlocicloselylinkedtoit.Ananalysabledifferenceorpolymorphismmustexistbetweenthedisease-carryingalleleandthenormalalleletodistinguishthem.Geneticdiagnosisis最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件D.Metabolicanalysisoffetaltissues Fetaltissuesorfluidscanbesubjectedtoanalysistodetectthecharacteristicmetabolicorcellulardefectsofaninheritedmetabolicdisease.D.MetabolicanalysisoffetalForthistypeofanalysistobecarriedout,thespecificenzymeormetaboliteofinterestmustbeexpressedinthefetaltissuessampled,andtherangeofnormalvaluesaswellastheassaysensitivityandreproducibilitymustbeestablishedwithinthetissueofinterest.ForthistypeofanalyAlthoughanincreasingnumberofinheritedmetabolicdiseasesareamenabletodirectDNA-baseddiagnosis,enzyme-basedtechniquesarestillusefulinsituationswherethedisease-causinggenehasnotbeenidentifiedorwheretheprecisemutationisnotknown.AlthoughanincreasingE.MicroarrayAnalysis

Muchoftheexcitementtodaycentersongeneexpressionprofilingthatusesatechnologycalledmicroarrays.E.MicroarrayAnalysisADNAmicroarrayisathin-sizedchipthathasbeenspottedatfixedlocationswiththousandsofsingle-strandedDNAfragmentscorrespondingtovariousgenesofinterest.ADNAmicroarrayisaAsinglemicroarraymaycontain10,000ormorespots,eachcontainingpiecesofDNAfromadifferentgene.Fluorescent-labeledprobeDNAfragmentsareaddedtoaskifthereareanyplacesonthemicroarraywheretheprobestrandscanmatchandbind.Completepatternsofgeneactivitycanbecapturedwiththistechnology.Asinglemicroarray最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件4.NewmethodsforprenataldiagnosisA.PreimplantationdiagnosisPreimplantationdiagnosisistheperformanceofprenatalgeneticanalysisonembryosoroocytespriortoimplantation.4.NewmethodsforprenataldiThistechnologyhastheadvantagethatitallowsprenataldiagnosistobecarriedoutmuchearlierthanexistingmethodssuchasamniocentesisandCVS.ThistechnologyhastheFurthermore,coupleswhoareatexceptionallyhighgeneticriskandthosewhohavehadpreviousterminationsforgeneticindicationsmayfindpreimplantationdiagnosisamoreacceptableformofprenataltesting.Furthermore,couples最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件Inthefuture,preimplantationdiagnosismayalsobeusedinconjunctionwithgenetherapy.Atpresent,giventheexpenseoftheprocedureandthesmallnumberofcentresequippedtoperformthisformofdiagnosis,preimplantationdiagnosisisunlikelytobecomeastandardprocedureintheforeseeablefuture.Inthefuture,preimplaAccesstooocyteandembryoniccells Preimplantationgeneticanalysiscanbecarriedoneitherembryoniccellsoroocytes.Inthelatersituation,diagnosisiscarriedoutevenpriortofertilisation.Individualoocytesareaspiratedandtheirpolarbodybiopsied.AccesstooocyteandembryonicForpreimplantationdiagnosiscarriedoutonembryoniccells,theembryomaybefertilisedinvitroandthenindividualblastomeresbiopsied.Alternatively,theembryomaybefertilisedinvivoandthentheembryosareobtainedbyuterinelavagefollowedbybiopsyandgeneticanalysis.ForpreimplantationdiagForheterozygouswomencarryingonemutantandonenormalalleleofadisease-causinggene,intheabsenceofchromosomalcrossing-over,theaspiratedpolarbodycontainingamutantallelewouldindicatethattheprimaryoocytepronucleusiscarryingthenormalallele.ForheterozygouswomenInbothsituations,onlytheembryosconfirmednottopossessthefulldisease-causinggenotypearethenimplantedbackintotheuterus.Inbothsituations,only最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件Diagnosticmethods PreimplantationdiagnosismaybeachievedusingPCR,FISHorbymeasurementofembryonicsecretoryproductssuchascertainenzymes.DiagnosticmethodsThistypeofanalysishasbeencarriedoutsuccessfullyforthedeterminationoffetalsexfortheavoidanceofsex-linkeddisorderssuchasDuchennemusculardystrophyandhaemophiliaA,andforthediagnosisofsinglegenedisorderssuchascysticfibrosis,alpha-1-antitrypsindeficiency,Tay-Sach'sdisease,fragileXandsicklecellanaemia.ThistypeofanalysisWorldwide,preimplantationdiagnosisofembryoshasbeenattemptedonover1,200invitrofertilisationcyclesin1997,withclinicalpregnancyresultedin20%.Noincreaseintheoccurrenceofabnormalitieshasbeenobservedintheliveborns.Worldwide,preimplantaB.NoninvasiveprenataldiagnosisusingfetalcellsisolatedfrommaternalbloodCircumstantialevidencethatfetalnucleatedcellsexistinmaternalperipheralbloodcanbetracedbackto1969.B.NoninvasiveprenataldiagnoHowever,convincingproofoftheexistenceofthesecellshavetoawaitthedevelopmentofmolecularbiologicaltechniques,especiallythePCR.However,convincingprUsingthePCR,investigatorsareabletodemonstratethepresenceofcellspossessingfetalgeneticmarkerscirculatingintheperipheralbloodofpregnantwomen.Theisolationofthesecellsofferthepossibilityofanoninvasiveandsafemethodforprenataldiagnosis.UsingthePCR,investigFetalnucleatedcelltypesinmaternalbloodThreepopulationsoffetalnucleatedcellsarecurrentlyknowntobepresentinmaternalperipheralblood:fetallymphocytes,trophoblastsandfetalnucleatedredcells.FetalnucleatedcelltypesinAtpresent,theisolationoffetalnucleatedredcellsisreceivingthemostattentionfrominvestigatorsinthefieldduetotheavailabilityofrelativelyspecificmonoclonalantibodiesagainstthesecells.Atpresent,theisolatIsolationoffetalcellsandgeneticanalysis Acombinationofphysicalandimmunologicalmethodsareusedtoisolatefetalnucleatedcellsfrommaternalblood.Physicalmethodsincludedensitygradientcentrifugationandmicromanipulationtechniqueswhileimmunologicalmethodsincludetheuseofmonoclonalantibodies.IsolationoffetalcellsandgGeneticanalysisoftheseisolatedfetalcellscanbeperformedusingPCRorFISH.Fetalcellsinmaternalbloodhavebeensuccessfullyusedonaresearchleveltodiagnosetrisomy21,trisomy18,beta-thalassaemiaandsicklecellanaemia.Actualclinicalusewillhavetoawaitfurthertechnologicaldevelopmenttoimproveitsreliabilityandclinicaltrialstoassessthesensitivityandspecificityofthisapproach.Geneticanalysisoft此課件下載可自行編輯修改，僅供參考！

感謝您的支持，我們努力做得更好！謝謝此課件下載可自行編輯修改，僅供參考！

感謝您的支持，我們努力18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease18疾病的產(chǎn)前診斷PrenatalDiagnosisofDiFurthermore,thepsychologicalstressonfamilieswithchildrenwithseriousgeneticdisordersisincalculable.Untilgenetherapybecomesapracticalreality,theonlyoptionavailableforthecontrolofgeneticdiseaseisprenataldiagnosis.Furthermore,thepsyc1.Indicationsforprenataldiagnosis

Theuseofprenataldiagnosisisdeterminedbybalancingtheriskofthebirthofanabnormalchildagainsttheriskofaninvestigativeprocedure.1.Indicationsforprenataldi

Thegeneralindicationsofprenataldiagnosisincludematernalageandtheresultsofnoninvasiveserumbiochemicalscreening.Thegeneralindicationsof

Specificindicationsincludeapositivefamilyhistoryandthebirthofapreviouschildaffectedbyaparticulargeneticdisease.Specificindicationsinclud2.Methodsforobtainingfetaltissuesforprenataldiagnosis

Toperformprenataldiagnosis,fetal-derivedtissuesmustfirstbeobtained.Allofthecommonlyusedmethodsthatyieldfetaltissuesareinvasive.

2.MethodsforobtainingfetalA.AmniocentesisAmniocentesisisthewithdrawalofamnioticfluidfromtheamnioticsacsurroundingthefetus.Forovertwodecadesthishasbeentheprimarytechniqueutilisedforthediagnosisoffetalgeneticdisorders.A.AmniocentesisTraditionallyamniocentesishasbeenperformedaround15to16weeksgestation.Atthistimetheuterusiseasilyaccessibletoatransabdominalapproach,andasufficientvolumeofamnioticfluid(approximately200ml)existstopermit20to30mltobewithdrawnsafely.TraditionallyamniocenAmniocentesisisnormallyperformedasanoutpatientfacility.Anultrasoundexaminationisnormallydoneimmediatelybeforetheproceduretoevaluatefetalnumberandviability,performfetalbiometricmeasurements,establishplacentallocation,andestimateamnioticfluidvolume.AmniocentesisisnormalAmniocentesisperformedconcurrentlywithultrasoundscanning.

AmniocentesisperformedconcurSafetyofamniocentesisAnyprocedurethatinvolvespassingadeviceintoanorgan,especiallythepregnantuterus,carrieswithitrisks;amniocentesisisnoexception.SafetyofamniocentesisAmniocentesisinvolvespotentialdangertobothmotherandfetus.Seriousmaternalrisksarequitelowbutincludeamnionitiswhichcanleadtofetalloss,haemorrhageorinjurytoanintra-abdominalviscusandleakageofamnioticfluid. AmniocentesisinvolvesFetalrisksincludespontaneousabortion,needlepunctureinjuries,placentalabruption,chorioamnionitis,pretermlabour,andamnioticbandformation.FetalrisksincludespSeveralcontrolledstudieshavebeendonetoevaluatetherisksofamniocentesis.Thedataindicatethattheriskofpregnancylossattributabletoamniocentesismaybeashighas0.5%.SeveralcontrolledstIngeneral,riskswilldependon(1)theexperienceoftheobstetricianperformingtheprocedure;(2)clinicalcharacteristicsofaparticularcase(e.g.,presenceorabsenceofbiochemicalmarkersoffetalabnormality);(3)thequalityofthehigh-resolutionultrasoundutilised.Ingeneral,riskswillEarlyamniocentesis

Withdevelopmentofhigherresolutionultrasoundequipment,somecentreshavebegunofferingamniocentesisbefore15weeksgestation,usuallybetween10and14weeks.Themajorityofprocedureshavebeenperformedduringthe13thand14thweeksofgestation.

EarlyamniocentesisThereisevidencethatearlyamniocentesisisassociatedwithahigherfetallossrateandamorefrequentoccurrenceofcertaincongenitalabnormalities.ThereisevidencethaB.Chorionicvillussampling

Chorionicvillussampling(CVS)istheonlytestedmethodforfirst-trimesterfetalgeneticdiagnosisthatiscurrentlyinclinicaluseandisusuallyperformedbetween9and11weeks.B.Chorionicvillussampling Theprocedureinvolvesthepassingofasamplinginstrumentintothechorion(developingplacenta).Agoodprocedureyieldsfrom10to25mgoftissuewhichisadequateforcytogenetic,enzymaticorDNAanalysis.TheprocedureinvolvesThemainadvantageofCVSoveramniocentesisistheapplicabilityofCVSearlieringestation.Thisresultsinconsiderablyreducedsocial,emotionalandpsychologicalstressforthecouple.ThemainadvantageofSafetyofCVS Maternalcomplicationsincludebleedingandinfection.FetallossfollowingCVShasbeenreportedtobearound2%.TherearealsoreportsoflimbreductiondefectsininfantsborntomotherswhohavehadCVSbetween56and66daysofgestation.SafetyofCVSC.Fetalbloodsampling(FBS) Fetalbloodcanbesafelyanddirectlysampledfromapproximately18weeksgestationonwards.FBScanbeusedforbothdiagnosticandtherapeuticpurposes.C.Fetalbloodsampling(FBS)

IndicationsforfetalbloodsamplingDiagnosticRapidkaryotypingFetalanomalyonultrasoundLateattendingpatientswhorequirefetalkaryotypingAlloimmunisationRhesusPlateletantigensFetalinfectionToxoplasmosisCytomegalovirusinfectionGeneticHaemoglobinopathiesMetabolicdisordersandenzymedeficienciesFetalwellbeingSevereintrauterinegrowthretardationTherapeuticTransfusionRedcellalloimmunisationTransplantationStemcells

FBSiscontraindicatedifthemotherissufferingfrominfectionsthatcanbetransmittedtothefetusbytheprocedure.ExamplesincludehumanimmunodeficiencyvirusandhepatitisBvirusinfection.FBSiscontraindicatedSafetyofFBSMaternalcomplicationsfromFBSareuncommonbutincludeamnionitis,infection,rhesussensitisationandtransplacentalhaemorrhage.SafetyofFBSFetallossratesfollowingFBShavebeenreportedtobeapproximately1%inseverallargeseries.Thepresenceofstructuralabnormalitiesorseveregrowthretardationofthefetusisassociatedwithamuchincreasedfetallossrate.FetallossratesfolloOtherfetalcomplicationsincludeinfection,prematureruptureofmembranes,haemorrhage,severebradycardiaandumbilicalcordthrombosis.OtherfetalcomplicatiD.FetalbiopsyAlthoughadvancesinmolecularandbiochemicalgeneticshavemadethediagnosisofmanyMendeliandisorderspossiblebyanalysisofamnioticfluidcellsorchorionicvilli,someconditionsstillrequiredirectanalysisoftissuesinwhichthedisorderismanifested.Tissueswhichhavebeensuccessfullybiopsiedincludefetalskin,liverandmuscle.D.FetalbiopsySafetyoffetalbiopsyDuetotherelativelysmallnumbersperformedindifferentcentres,noprecisefiguresforthesafetyoffetalbiopsyisavailable.Safetyoffetalbiopsy3.AnalyticalmethodsFollowingtheacquisitionoffetaltissues,thesematerialsarethensubjectedtoanalysisusingavarietyoftechniques.3.AnalyticalmethodsFA.Cellcultureandconventionalcytogenetics

ThesearethemostcommonlyusedmethodsforthediagnosisofchromosomalaneuploidiessuchasDownsyndrome.A.CellcultureandconventionB.MolecularcytogeneticsusingFISHFISHinvolvesthehybridizationofDNAprobesrepresentingaspecificchromosomeorchromosomalregiontotargetDNAsuchasmetaphasechromosomesorinterphasenuclei,wheretheprobebindstohomologoussequencesinthecell.B.MolecularcytogeneticsusinUsingFISH,severalgroupshavedemonstratedthattrisomiessuchastrisomy21andtrisomy18canbedetectedinunculturedinterphasenucleiasthreepositivehybridisationsignalsratherthanthenormaltwo.UsingFISH,severalgroThemainadvantageisspeed:thusresultsareavailablein24to48hourscomparedwiththe10to14daysmoretypicalofstandardculture-basedcytogeneticanalysis.Thistypeoftechnologycanbeappliedtofetalmaterialsobtainedfollowingamniocentesis,CVSorfetalbloodsampling.ThemainadvantageisspC.DNA-basedtechniquesThemainadvantageofDNA-basedtechniquesisthatanynucleatedfetalcellcanbeused.Techniqueswhichareusedincludethepolymerasechainreaction(PCR)andSouthernblotting.

C.DNA-basedtechniquesPCR-basedtechniquesallowarapiddiagnosistobemadeinseveralhours.Thesemethodscanbeusedfordirectmutationdetectionorlinkageanalysis.Thelattertypeofanalysisisneededwhentheexactmutationorgenecausingthediseaseisnotknown.PCR-basedtechniquesa最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件GeneticdiagnosisisthencarriedoutbyanalysingDNAsequenceswithinthegeneitselforDNAlocicloselylinkedtoit.Ananalysabledifferenceorpolymorphismmustexistbetweenthedisease-carryingalleleandthenormalalleletodistinguishthem.Geneticdiagnosisis最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件最新18疾病的產(chǎn)前診斷PrenatalDiagnosisofDisease課件D.Metabolicanalysisoffetaltissues Fetaltissuesorfluidscanbesubjectedtoanalysistodetectthecharacteristicmetabolicorcellulardefectsofaninheritedmetabolicdisease.D.MetabolicanalysisoffetalForthistypeofanalysistobecarriedout,thespecificenzymeormetaboliteofinterestmustbeexpressedinthefetaltissuessampled,andtherangeofnormalvaluesaswellastheassaysensitivityandreproducibilitymustbeestablishedwithinthetissueofinterest.ForthistypeofanalyAlthoughanincreasingnumberofinheritedmetabolicdiseasesareamenabletodirectDNA-baseddiagnosis,enzyme-basedtechniquesarestillusefulinsituationswherethedisease-causinggenehasnotbeenidentifiedorwheretheprecisemutationisnotknown.AlthoughanincreasingE.MicroarrayAnalysis

Muchoftheexcitementtodaycentersongeneexpressionprofilingthatusesatechnologycalledmicroarrays.E.MicroarrayAnalysisADNAmicroarrayisathin-sizedchipthathasbeenspottedatfixedlocationswiththousandsofsingle-strandedDNAfragmentscorrespondingtovariousgenesofinterest.ADNAmicroarrayisaAsinglemicroarraymaycontain10,000ormorespots,eachcontainingpiecesofDNAfromadifferentgene.Fluorescent-labeledprobeDNAfragmentsareaddedtoaskifthereareanyplacesonthemicroarraywheretheprobestrandscanmatchandbind.Completepatternsofgeneactivitycanbecapturedwiththistechnology.Asinglemicroarra

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