pre-implantation genetic diagnosis ( pgd )

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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