get
Post on 22-Nov-2014
594 Views
Preview:
DESCRIPTION
TRANSCRIPT
Ethics in GeneticsAssociate Professor Martin Delatycki
Director Bruce Lefroy CentreMurdoch Childrens Research Institute
Consultant Clinical GeneticistGenetic Health Services Victoria
MCRI• Largest paediatric research institute in the Southern
Hemisphere
• 60 research groups in 6 themes
• ~900 staff
• Located at the Royal Children’s Hospital
Bruce Lefroy Centre• 28 staff
• Research into neurogenetic diseases (Friedreich ataxia, Parkinson disease, Huntington disease, dystonia)
• Community genetic research (haemochromatosis, cystic fibrosis, Tay Sachs disease)
• Genetic ethics research
THE HIPPOCRATIC OATH– I swear … the following Oath: To consider dear to me as
my parents him who taught me this art ……. – I will prescribe regimen for the good of my patients
according to my ability and my judgment and never do harm to anyone. To please no one will I prescribe a deadly drug, nor give advice which may cause his death. Nor will I give a woman a pessary to procure abortion. …... In every house where I come I will enter only for the good of my patients, keeping myself far from all intentional ill-doing and all seduction……….... All that may come to my knowledge in the exercise of my profession ………... which ought not to be spread abroad, I will keep secret and will never reveal. If I keep this oath faithfully, may I enjoy my life and practice my art, respected by all men and in all times; but if I swerve from it or violate it, may the reverse be my lot.
Principles
• Autonomy
• Benificence
• Non malificence
• Justice
Autonomy
• Self-rule
• Ability to make decisions for oneself on the basis of deliberation
Beneficence
• Acting so as to benefit others
Non maleficence
• Not harming others
Justice
• Moral obligation of fairness.
• Treating people equally in relation to criteria acknowledged to be morally relevant.
• Great variability in different societies, cultures and religions
In 2008 what has changed?• Options of genetic testing provide new choices
• the type of children we have• information (management ) - future health
• Doctor patient relationship in genetics• patient/client• gene affects the family; who is the patient
• Duty of care ----> ?duty to warn• confidentiality/disclosure measured by the greatest potential harm
Case studies
1:2 Chance of the condition in child of affected parent
Prenatal Options
• Traditional prenatal diagnosis– Chorionic villus sampling
• Preimplantation genetic diagnosis
Chorion Villous SamplingCVS
•11-15 weeks
•Diagnosis– Chromosome abnorm.
– DNA Studies
– Biochemical studies
•1:100 miscarriage
Preimplantation Genetic Diagnosis- PGD• In the context of IVF
• Testing by embryo biopsy
• Chromosomal abnormalities
• Selected single gene disorders
• Most common reason an objection to TOP or previous TOP following PND.
• No apparent increase in birth defects
PGD
+
PGD
- DNA extracted and mutation detection testing done
Method of embryo biopsy
The hole in the zona allows entry of a micro pipette to aspirate 1 or 2 cells from the embryo.
The cell can then be fixed to a slide, or placed in solution to allow genetic analysis.
PGD for single gene disorders
• Requested by couples wishing to avoid TOP• 97% diagnostic accuracy• 20% pregnancy rate per cycle• Cystic fibrosis most common indication• Counselling by both Genetics and IVF team
Client 1• Alan and his partner Helen are both deaf and they are
planning to have children. • Alan has severe deafness as do both his father and his
paternal grandfather. He grew up surrounded by deaf people.
• Genetic testing has shown that Alan’s deafness is due to an autosomal dominant mutation.
• Helen is the first in her family with deafness and this was thought to be due to exposure to a drug as baby.
• The couple communicate by sign language
Client 1• They come to you seeking prenatal diagnosis. They
know that there is a 50% chance for each child to be deaf based on the dominant mutation found in Alan.
• They state that they want their children to be deaf like them so they can experience the D/deaf culture they live in. They request prenatal or preimplantation genetic diagnosis with selection for deafness.
• Can you help them?
Pre-implantation selection for deafness - the views of hearing children of deaf adults
Cara Mand
Martin Delatycki
Rony Duncan
Lynn Gillam
Background• Duchesneau and McCullough deaf lesbian couple• Wanted a deaf child • “Congenital deafness is precisely the sort of
condition that disqualifies would be donors (Spriggs 2002)”
• Sperm from friend with 5 generations of deafness• “ a hearing baby would be a blessing. A deaf baby
would be a special blessing”
Defining deafness
d/deaf D/deaf
• medical model (disability)
• d/deaf individuals- minority in hearing world
• often deaf later in life orhave partial hearing loss
• social model (linguisticminority)
• D/deaf individuals - separate cultural group often deaf from birth
D/deaf
• “… Deaf people like being deaf, want to be deaf, and are proud of their deafness… they claim the right to personal diversity, which is something to be cherished rather than fixed or erased” (Tucker 1998)
Current debate / controversy
• Against selection for deafness…• selecting deafness = denying the child of an open future• Often:
– Medical professionals – Hearing community– d/deaf individuals – Ethicists
• “We’d like to be able to hear our children and grandchildren laugh and cry, listen to the radio… the list is endless. Why would any human being want to deny such pleasure to herself or her children?” (Tucker 1998)
For selection for deafness…• Deafness not a disability
• Their choice to make
• Often (but not always): – Ethicists– Geneticists/ genetic counsellors– D/deaf individuals
• “Deaf people are disabled more by their transactions with the hearing world than by the pathology of their hearing impairment” (Munzo-Baell 2000)
Project • To gain insight into the attitudes of hearing
children of deaf adults, to selection for deafness
• Already know the views of both the hearing and Deaf community towards selection for deafness
• Hearing children of deaf adults – Ideally placed, experience in both hearing and deaf world
Project• 2 Stage process, adopting qualitative and quantitative
research methods
• 1st: individuals from CODA and health professionals. Semi-structured interviews. Answers analysed and used to compile a survey for second group of participants .
• 2nd: Anonymous survey broadcast electronically. Answers explored and similarities extracted and analysed.
• Through CODA (worldwide organisation)
Deafness as a Disability vs. Culture
Categories No. ofParticipants
(n = 66)
Percentage(%)
Distinct culture /Difference
30 45.5
Disability 0 0Both 33 50Unsure 0 0Other 3 4.5
PND
SituationsDeaf parentswanting deaf
children
Deaf parentswanting hearing
children
Hearing parentswanting hearing
children
Hearing parentswanting deaf
children
Options Y N Y N Y N Y NMale% of males
321.4%
1178.6%
214.3%
1285.7%
214.3%
1285.7%
321.4%
1178.6%
Female% of females
611.5%
4688.5%
47.7%
4892.3%
713.5%
4586.5%
47.7%
4892.3%
X2 0.92 0.58 0.01 2.20
P-value 0.39 0.6 1.0 0.16
PGD
SituationsDeaf parentswanting deaf
children
Deaf parentswanting hearing
children
Hearing parentswanting hearing
children
Hearing parentswanting deaf
children
Options Y N Y N Y N Y NMale% of males
321.4%
1178.6%
214.3%
1285.7%
321.4%
1178.6%
214.3%
1285.7%
Female% of females
1019.2%
4280.8%
713.5%
4586.5%
917.3%
4382.7%
713.5%
4586.5%
X2 0.03 0.01 0.13 0.01
P-value 1.0 1.0 0.71 1.0
Huntington Disease
• Neurodegenerative• Onset on average in 40’s (4-80)• Death on average 15 years from onset• Chorea, dementia, personality change• No treatment known to change outcome
• Autosomal dominant- all due to one mutation
Client 2
• Max has a family history of Huntington disease. He has predictive testing that shows that he has inherited the condition.
• Max has two children- Ben is 8 and Nancy is 6. He requests that they be tested- do you test the children?
Genetic Testing of Children
• To make diagnosis- uncontroversial (eg: Duchenne muscular dystrophy)
• Where preventative treatment in childhood is proven- relatively uncontroversial
• Where no treatment is available and onset is adulthood- predictive testing- controversial
Predictive Genetic Testing of Children
• Genetic societies- should not do so as it removes the right of that person to make their own decision
• Most adults choose NOT to have this testing
• The child may be treated differently to their detriment if their genetic status is known
Predictive Genetic Testing of Children
• Alternate view eg: Prof Julian Savulescu-– Knowing status from childhood will allow that
person to grow up with the knowledge of their genetic status and adjust to this
Empirical Evidence
• Very little
• Following studies by Rony Duncan, Martin Delatycki, Bob Williamson, Julian Savulescu, Lynn Gillam
Clinical Geneticist Survey
• Web-based survey sent to:
- Members of the Australasian Association of Clinical Geneticists (98)
- Members of the Clinical Genetics Society of the UK (400)
- All Medical Doctors who are members of the American Society of Human Genetics (1732)
• The target was Clinical Geneticists• Responses were received as anonymous e-mails
22 Tests in Immature Minors
• HD- 4• DM- 4• CMT- 3• BMD- 2• VHL- 2• SCA- 2
27 Tests in Mature Minors
• HD- 14• DM- 5• BRCA- 3• FSHD- 2• SCA- 2
Follow-up
• 18/27 some follow-up• 2 adverse events
– “Initial depression and rebellion but eventual acceptance” HD +ve 17 year male
– “No psychological disturbance but worry and responsibility for affected mother and untested brothers” HD -ve 17 year female
• 9 reports of benefits
? Agree with Guidelines
• The majority of respondents agree with the existing guidelines, but feel that each case needs to be assessed individually
Views on existing guidelines
• 47% strongly agree • 35% agree• 3% don’t know• 5% disagree• 2% strongly disagree
Views on existing guidelines
• A strong theme of ‘each case must be assessed on its own merits’
“ I support informed consent for testing and some minors are capable of providing it, others are not”
“ I don’t believe in a rigid cut-off age … as I believe obtaining maturity to gain informed consent is a gradual process”
“ Occasionally there are exceptions to the age limit and one has to be flexible”
Interviews with Young People• 18 interviews with young people who had undergone
predictive genetic tests
• 8 young people who were tested for HD- 2 gene-positive & 6 gene-negative- Tested between ages of 17 and 25 yrs
Thinking Gene-Positive
“I’m a very pessimistic person, I was always saying it’s going to be positive, it’s going to be positive… it wouldn’t have been so much of a shock because I’ve sort of said to myself, you know, I’m going to be positive anyway”
Travis:M:24:HD:20:-ve
“Knowing that there’s a 50:50 chance, it’s just, like it’s always in your head that yes I have it, rather than no I don’t have it”Zach:M:26:HD:23:-ve
“I just thought I had it, obviously I didn’t have signs or anything, but like, in my head, yeah”
Poppy:F:24:HD:17:-ve
Living Again“I’ve gotten off drugs since I found out”
Nina:F:23:HD:23:-ve
“Since I’ve been tested I’ve been pretty good… I haven’t been in trouble with the police or anything… I seem to have changed a bit, just come out of me shell.. You know.. A bit happier and stuff… I want to start me own business”
Troy:M:26:HD:25:-ve
“I thought well, if I can go through this whole process of getting tested for this thing, I can pretty much do anything… I respected myself a lot more for that”
Travis:M:24:HD:20:-ve
Living Again
“It stopped me from living effectively at the time, I mean, I did the day to day things, I went to school, I ate dinner… but, didn’t feel like I was living kind of thing, like I had a life but I wasn’t living. Once I had the knowledge, that was it, ok, fine, you know… knowing but not knowing in a way… knowing that if I live long enough I will develop symptoms one day, um, but now knowing exactly what the rest of my life has in store for me and allowing me just to accept that and just live.”
Belinda:F:25:HD:21:+ve
Holding Your Breath
“All my life I thought I was going to get this illness, all my life, and last year I found out I didn’t, you know, so for 19 years it feels like I’ve held my breath, thinking that I’m going to get this illness, and now it feels like I’m a newborn child, you know, like, I can live a life I never knew I could. It seems really weird to adjust to, like, the whole time I thought I was going to get it and then she told me I didn’t have the gene… and I felt like I could breathe for the first time in 19 years”
Ella:F:20:HD:18:-ve
Client 3• Sonya requests prenatal diagnosis (PND) for HD as her
partner Colin is at 50% risk
• Colin has stated that he does not wish to know his HD status and he would suicide if he found he had the mutation
• Sonya says if the PND is positive she would tell Colin she miscarried
• Do you offer Sonya PND?
top related