Prenatal diagnosis for Prenatal diagnosis for Joubert syndrome: Joubert syndrome: Challenges and Possibilities Challenges and Possibilities Ian A. Glass, MB ChB, MD, FACMG Ian A. Glass, MB ChB, MD, FACMG Associate Professor of Pediatrics and Associate Professor of Pediatrics and Medicine Medicine
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Prenatal diagnosis for Joubert syndrome: Challenges and Possibilities
Prenatal diagnosis for Joubert syndrome: Challenges and Possibilities. Ian A. Glass, MB ChB, MD, FACMG Associate Professor of Pediatrics and Medicine. Prenatal Diagnosis (PND) Topics for this seminar. Goals of PND in general Methods of PND PND in Joubert syndrome - PowerPoint PPT Presentation
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Prenatal diagnosis for Joubert Prenatal diagnosis for Joubert syndrome:syndrome:
Challenges and PossibilitiesChallenges and Possibilities
Ian A. Glass, MB ChB, MD, FACMGIan A. Glass, MB ChB, MD, FACMG
Associate Professor of Pediatrics and MedicineAssociate Professor of Pediatrics and Medicine
Prenatal Diagnosis (PND)Prenatal Diagnosis (PND)Topics for this seminarTopics for this seminar
• Goals of PND in generalGoals of PND in general
• Methods of PNDMethods of PND
• PND in Joubert syndromePND in Joubert syndrome
• Strengths/weaknesses of PND for JSStrengths/weaknesses of PND for JS
• Future directions for PND of JSFuture directions for PND of JS
Goals of PNDGoals of PND• Facilitate informed reproductive choices Facilitate informed reproductive choices
• Reduce anxiety in high-risk groupsReduce anxiety in high-risk groups
• Enable prenatal treatment, if availableEnable prenatal treatment, if available
• Ensure the birth of unaffected infantsEnsure the birth of unaffected infants
(termination of affected fetus)(termination of affected fetus)
• Enable preparations for the birth of an Enable preparations for the birth of an affected child affected child
Reproductive options for couples Reproductive options for couples who have a child with JSwho have a child with JS
• Accept the risk without PNDAccept the risk without PND
• Accept the risk and consider PND imaging:Accept the risk and consider PND imaging:– To be prepared for an affected childTo be prepared for an affected child– To terminate an affected fetusTo terminate an affected fetus
• Sperm or egg donor to reduce riskSperm or egg donor to reduce risk
• Choose to adoptChoose to adopt
• Choose not to have additional childrenChoose not to have additional children
ALL of these choices are valid!
Methods of PNDMethods of PND• Non-invasive testingNon-invasive testing
• serum markers serum markers • imaging by ultrasound, fetal-MRIimaging by ultrasound, fetal-MRI
• Ultrasound (US)Ultrasound (US)• Fetal MRIFetal MRI• Screening for high risk groups (e.g. AMA)Screening for high risk groups (e.g. AMA)• Directed diagnostic imaging for:Directed diagnostic imaging for:
• Fetuses with abnormalitiesFetuses with abnormalities• Family history of birth defectFamily history of birth defect
• Post-natal correlations to confirm PND predictionPost-natal correlations to confirm PND prediction• Postnatal follow-up exam and/or testingPostnatal follow-up exam and/or testing• Fetal autopsy if demise or terminationFetal autopsy if demise or termination
Correlations often not performed !!!Correlations often not performed !!!
• imaging by ultrasound, fetal-MRIimaging by ultrasound, fetal-MRI YESYES
Most of these methods are not useful because chromosomal, DNA* Most of these methods are not useful because chromosomal, DNA*
and protein markers for JS are not availableand protein markers for JS are not available
*If a known mutation in a JS gene
Is DNA testing currently available for JS?Is DNA testing currently available for JS?
• Best situation: one gene causes all JS casesBest situation: one gene causes all JS cases–But we have at least 5 JS genes known/mapped But we have at least 5 JS genes known/mapped alreadyalready
• Goal: direct DNA testing once JS genes are knownGoal: direct DNA testing once JS genes are known• 2006: Only two direct DNA tests are clinically 2006: Only two direct DNA tests are clinically “available” for JS for the “available” for JS for the NPHP1 NPHP1 and and AHI1 AHI1 genes,genes, accounting for <15% of JSaccounting for <15% of JS• Specific Specific genegene testing may be indicated if an older testing may be indicated if an older sibling has a mutation in a known JS genesibling has a mutation in a known JS gene
What is available now?What is available now?
• Prenatal imaging by ultrasound scanning Prenatal imaging by ultrasound scanning (considerable experience)(considerable experience)
• Prenatal imaging by fetal MRI scanning Prenatal imaging by fetal MRI scanning (increasing experience)(increasing experience)
PND of JSPND of JSFamily History is KeyFamily History is Key
Cerebellar vermis in uteroCerebellar vermis in utero
Normal HypoplasticNormal
JS in utero: JS in utero: absence of cerebellar vermisabsence of cerebellar vermis
UltrasoundUltrasound MRIMRI
JS: enlarged cisterna magnaJS: enlarged cisterna magna
UltrasoundUltrasound MRIMRI
JS in utero:JS in utero:polydactylypolydactyly
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5
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Aslan et al. 2002
JS in utero:JS in utero:encephaloceleencephalocele
Wang et al. 1999
US for PND: promise and perilsUS for PND: promise and perils• Advantages:Advantages:
– Non-invasiveNon-invasive– Can see important structures: brain, fingers, kidneysCan see important structures: brain, fingers, kidneys– Can be repeated throughout pregnancyCan be repeated throughout pregnancy– Relatively inexpensiveRelatively inexpensive– Standardized measurementsStandardized measurements
• Disadvantages:Disadvantages:– Technician-dependent: angle of transducerTechnician-dependent: angle of transducer
– Observer-dependent: experience in looking at brainObserver-dependent: experience in looking at brain
– May not see subtle abnormalities May not see subtle abnormalities
– Timing is crucial: defects may not be visible earlyTiming is crucial: defects may not be visible early
For couples who desire prenatal imagingFor couples who desire prenatal imaging
• 11-12 wks: baseline US for dates, nuchal fold11-12 wks: baseline US for dates, nuchal fold• 16 wks: US for cranial views, skull, fingers, kidney16 wks: US for cranial views, skull, fingers, kidney• 18 wks: US to confirm cerebellar growth18 wks: US to confirm cerebellar growth• 20-22 wks: US for above + fetal MRI20-22 wks: US for above + fetal MRI• Further imaging, dependent on prior findingsFurther imaging, dependent on prior findings• If possible, review by an experienced radiologist, or If possible, review by an experienced radiologist, or
perinatologist in evaluations of the posterior fossaperinatologist in evaluations of the posterior fossa
Improving PND of JSImproving PND of JS• Systematic review of prenatal imaging Systematic review of prenatal imaging • Correlation with outcomesCorrelation with outcomes• Follow ongoing pregnancies with imaging studiesFollow ongoing pregnancies with imaging studies
• HypothesisHypothesis: Systematic review of ultrasound and/or : Systematic review of ultrasound and/or fetal MRI imaging will improve diagnosis of JS and fetal MRI imaging will improve diagnosis of JS and generate guidelines for prenatal monitoring of at-risk generate guidelines for prenatal monitoring of at-risk pregnanciespregnancies
JS PND SummaryJS PND Summary
• Can we diagnose JS prenatally given a prior Can we diagnose JS prenatally given a prior family history?family history?– Sometimes, but the reliability is unknownSometimes, but the reliability is unknown
• Can we diagnose JS prenatally without a prior Can we diagnose JS prenatally without a prior family history?family history?– Almost never, if at allAlmost never, if at all
• Improved PND is needed, imaging is our best Improved PND is needed, imaging is our best option at this timeoption at this time
Making an informed choiceMaking an informed choice
• A Genetic Counselor or Geneticist can helpA Genetic Counselor or Geneticist can help– Discuss optionsDiscuss options– Provide resources and support Provide resources and support
• When possible, get information prior to When possible, get information prior to getting pregnant (preconception counseling)getting pregnant (preconception counseling)
• www.genetests.orgwww.genetests.org or or www.nsgc.orgwww.nsgc.org for a for a list of local genetic counselorslist of local genetic counselors
– Ian A. Glass, MD and Dan Doherty, MD, PhDIan A. Glass, MD and Dan Doherty, MD, [email protected]@[email protected]@seattlechildrens.org206-987-5142206-987-5142206-987-2489206-987-2489