pre-implantation genetic diagnosis ( pgd )
TRANSCRIPT
MarwanAlhalabiMDPhDProfessorinReproductiveMedicineFacultyofMedicineDamascusUniversity
&ClinicalMedicalDirectorOrientHospitalAssistedReproductionCenterDamascus,Syria.
• PGD is a state-of-the-art procedure used
in conjunction with In Vitro Fertilization
(IVF) in which the embryo is tested for
certain conditions prior to being placed in
the womb of the woman.
• PGD was first reported in 1990.
• PGD combines the recent advances in
molecular genetics and in assisted
reproductive technology
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World-wide, over 100,000 babies were born thanks to PGD
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Embryo biopsyDiagnosis
by
Transfer1-2 unaffectedembryos
Fertilisation in vitro (IVF or ICSI)
PCRFISH
Accurate genetic
diagnosisAppropriate Genetic
Counselling
DENATURING
ANNEALING
EXTENSION
PRIMER
TAQ
TAQ
Ovarian Stimulation IVF Blastomere Biopsy on Day 3
Genetic AnalysisTransfer of Unaffected
EmbryoOutcome
Chromosomally Normal Baby
• PolarBody
• CleavageStage
• Blastocyst
Donotprovidediagnosisofpaternalalleles&the
gender theembryo.
• PolymeraseChainReaction(PCR).
• FluorescenceInSituHybridization(FISH).
• CGH24.
• DNAMicroarrays.
• NGS(nextgenerationsequencing).
XchromosomeYchromosomeChromosome21
• ChromosomalDisorders
• Chromosomalrearrangements
• Inversions
• Translocations
• ChromosomeDeletions
• Genderdeterminationforsevere
X-linkeddiseases
• Severe monogenic diseases(cystic fibrosis, ß thalassaemia, sickle
cell anemia, fragile X syndrome,
myopathies)
• Recurrent pregnancy loss.
• AdvancedMaternalAge.
• Coupleswith >3 IVF failures.
• Epididymal or Testicular sperm
aspiration with >1 IVF failures.
• Unexplainedinfertility.
• Y-chromosomedeletion:foundin
5-20%menwithlowspermcount.
• Coupleswhohave previouslyhada
pregnancywithachromosomal
abnormality.
• coupleswhereonepartnercarries
abalancedchromosomal
translocations.
AUTOSOMALRECESSIVECysticfibrosis(variousmutations)TaySachsdiseaseb-thalassaemiaSicklecellanaemiaRhbloodtypingSpinalmuscularatrophyAdrenogenital syndromeCongential adrenalhyperplasiaPlakophilin-1(PKP1)MCADCDG1CEpidermolysis bullosaGaucher’s diseaseHyperinsulinemic hypoglycemia PHH1Fanconii’s anemiaHLAmatching
TRIPLETREPEATSFragileXMyotonic dystrophyHuntingtons
AUTOSOMALDOMINANTMarfans syndromeCharcot-MarieToothdisease(type1A)Crouzons syndromeNF2Osteogenesis impeerfecta IandIVSticklersyndromeTuberoussclerosisCentralcorediseaseFamilialadenomatouspolyposisLiFraumeni syndromeRetinoblastoma
SPECIFICDIAGNOSISOFX-LINKEDLesch Nyhan syndromeDuchenne musculardystrophyCharcot-MarieToothdiseaseRetinitispigmentosumOrnithineTranscarbamylaseHaemophiliaAgammaglobulinemiaAlport syndromeHunter’ssndrome MPSIIOro-facial-digital syndrometypeI
• X-linked,agammaglobulinemia• Spinalandbulbarmuscularatrophy• FGsyndrome• DAZdeletion• Ataxiatelangiectasia• Familialamyloidotic polyneuropathy• Genodermatosis (PKP1)• Charcot-Marie-Tooth typeIA• Citrullinemia• Holoprosencephaly (SSHgen)• Kelley-Seegmil syndrome• X-linkedepilepsy(paternalside)• Mitochondrial MELAS• Pelizaeus Merzbacher• Junctional epidermolisis bullosa• Hyperinsulinemic hypoglycemiaPHH1• Fabry’s disease• Bloomdisease• Anemia• FAP-Gardner• CF+XLmentalretardation (X2)• Oro-facial-digitalsyndrometype1
• Incontinentia pigment• RhD sensitization• Adrenoleukodystrophy• Osteogenesis imperfecta• CDG1C• Skinfragility• Alfa-1-antitrypsindeficiency• Hypophosphatasia• Lesch Nyhan syndrome• Long-chain3-hydroxyacyl-coa
dehydrogenasedeficiency• Marfan disease• FragileX• Retinoblastoma• Gaucher disease• Congenitaladrenalhyperplasia• Tuberosclerosis• Sticklersyndrome• Neurofibromatosis• Crouzon syndrome• ZFX/ZFY
• β-thalassemia• Sicklecellanemia• Cysticfibrosis• Spinalmuscularatrophy• Myotonic dystrophy• Duchenne musculardystrophy• HemophiliaAB• Epidermolizis bullosa• Multipleepiphysealdysplasia• Phenylketonuria (PKU)• Achondroplasia• X-linkedhydrocephaly• Retinitispigmentosa• Huntington disease• Hurlersyndrome• Huntersyndrome• OCT• Tay-Sach’s disease• Alport disease• Machado-Joseph disease• Glicogen Storagedisease• Koroideremi• X-linkedautism
• Increased Implantation Rate.
• Reduction in Pregnancy Losses.
• Reduction in the Chance of Havinga Child with Aneuploidy.
• Reduces the possibility of havingto choose to terminate thepregnancy following a diagnosis ofa probable genetic disorder.
• The birth of a(nother) child with a genetic disorder.
• Invasive diagnostic procedures including CVS andamniocentesis.
• Possibility of an established pregnancy termination.
• Risk of miscarriage due to genetic disorders
• Risk of future fertility problems.
• EmbryodamageOocyteandEmbryoBiopsyareinvasiveprocedures
• Misdiagnosis TheaccuracyofthePGDfortranslocationis90%.
• Falsenegativeresult
• Falsepositiveresult
• ThechanceforNOresult
• Thechanceformosaicism
• IVFRisks
TheuseofspecialprecautionstoavoidexogenousDNA
contaminationhasdramaticallyreducedthemaincausesof
misdiagnosis.
• NotAchievingPregnancy• Theremaynotbeanynormalembryosavailablefortransfer.
• Theembryosmaynotimplantanddevelopeveniftheydonothavethedefect.
• TheworkupforPGDisexpensive andlaborintensive.
• PGDcanonlydetectaspecificgeneticdiseaseinanembryo.Itcannotdetectmanygeneticdisordersatatimeandcannotguaranteethatthefetuswillnothaveanunrelatedbirthdefect.
FutureofPGD
• Effortscontinuetobefocusedonimprovingmethodstoobtainanaccuratediagnosis.
• PGDholdsgreatpromiseforthefutureastechniquesandgenetictestsareperfected.
• PGDmaybecomeroutineinthenextfewyears.
Withtheadventofthemicroarraytechniquesfortheanalysisofthegenome,transcriptsofthousandsofgenescanbetestedatonetime,andthecombinationofbothmightdramatically
changeourfuture
• PGDisareliableprocedureinpreventingthebirthofaffectedchildren.
• PGDofaneuploidyiseffectiveandresultsinahightakehomebabyratewhenimplementedincertaincategoriesofpatients.
• DespitetheefficiencyofthePGDtechnique,conventionalprenataldiagnosisisstillrequiredbymostPGDlaboratories
PGDforaneuploidyisavaluableandeffectivetoolforincreasingART
outcomeanddecreasingtherateofabortionincasesof advancedmaternal
ageandseveremaleinfertility
ThedevelopmentofPGDisoneofthemostexcitingandimportantmilestonesinthehistory
ofAssistedReproductiveTechnology
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