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Genetic testing for CF
Genetic testing for CF
Testing the individual
Testing the individual
Genetic screening for the CF gene
Genetic screening for the CF gene
How genetic testing is done
How genetic testing is done
Summary
Summary
How genetic testing is done
How genetic testing is done
Genetic testing for CF
Genetic testing for CF
How genetic testing is done
How genetic testing is done
From cells from a foetus
From cells from a foetus
http://www
http://www
Needle inserted into amniotic fluid
Needle inserted into amniotic fluid
Limitations of amniocentesis
Limitations of amniocentesis
2: Chorionic villus sampling Alternative to amniocentesis
2: Chorionic villus sampling Alternative to amniocentesis
Transcerivcal CVS
Transcerivcal CVS
Transabdominal CVS
Transabdominal CVS
Advantages of CVS
Advantages of CVS
DNA from an embryo
DNA from an embryo
Remove a cell from the embryo at the 8-16 cell stage (a few days old)
Remove a cell from the embryo at the 8-16 cell stage (a few days old)
Advantages No pregnancy to terminate Know that baby will not have CF
Advantages No pregnancy to terminate Know that baby will not have CF
Disadvantages Expensive IVF itself expensive and still fairly
Disadvantages Expensive IVF itself expensive and still fairly
Q&A: Embryo test http://news
Q&A: Embryo test http://news
What options are there if the test is positive for CF
What options are there if the test is positive for CF
What options are there if the test is positive for CF
What options are there if the test is positive for CF
Why might people choose not to test even if was offered to them
Why might people choose not to test even if was offered to them
This type of test could benefit parents who are known to be carriers
This type of test could benefit parents who are known to be carriers
If both parents are found to be carriers, what are the options open to
If both parents are found to be carriers, what are the options open to
The first UK babies have been born after a pioneering embryo test http
The first UK babies have been born after a pioneering embryo test http
What diseases can be treated with pre-implantation genetic diagnosis
What diseases can be treated with pre-implantation genetic diagnosis
Moral and ethical dilemmas of genetic screening
Moral and ethical dilemmas of genetic screening
Positives and Negatives of Genetic Screening
Positives and Negatives of Genetic Screening
Positives of Genetic screening
Positives of Genetic screening
Allows early intervention prenatal testing termination If know, can
Allows early intervention prenatal testing termination If know, can
Identification of genes associated with illness
Identification of genes associated with illness
Negatives of Genetic screening
Negatives of Genetic screening
A temporary ban on the results of genetic tests being made available
A temporary ban on the results of genetic tests being made available
Employment Treated differently
Employment Treated differently
Risk of miscarriage of a healthy baby Risk of false negatives so
Risk of miscarriage of a healthy baby Risk of false negatives so
Further Info
Further Info
Genetic testing for CF
Genetic testing for CF
Checkpoint 2.7. ethics of genetic screening; Is it or is it not
Checkpoint 2.7. ethics of genetic screening; Is it or is it not
Maximising the amount of good in the world Unethical to bring a child
Maximising the amount of good in the world Unethical to bring a child
Making decisions for yourself
Making decisions for yourself
Leading a virtuous life
Leading a virtuous life
An effective genetic screening programme must be
An effective genetic screening programme must be

Презентация: «Genetic testing for CF». Автор: dab. Файл: «Genetic testing for CF.ppt». Размер zip-архива: 562 КБ.

Genetic testing for CF

содержание презентации «Genetic testing for CF.ppt»
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1 Genetic testing for CF

Genetic testing for CF

See weblinks/ interactive for genetic screening on snab sit3

2 Testing the individual

Testing the individual

Since 1 in 25 people in the population are carriers the first time they will realise they carry the CF allele is when they have a baby with CF so testing new born babies routinely for CF allows early diagnosis, early intervention and management of the disease condition. CF sufferers have higher levels of salt in the sweat; test measures the level of salt in sweat. New born babies screened for higher than normal levels of the protein trypsinogen in blood (inactive form of the pancreatic protease trypsin – pancreatic duct blocked so cannot be secreted so levels build up)

3 Genetic screening for the CF gene

Genetic screening for the CF gene

Knowledge of the code in normal CFTR gene and the abnormal CFTR gene has led to the ability to identify the abnormal gene. Testing (= screening) for the abnormal CF allele of the gene is done; to identify carriers (especially if there is a history of CF in the family) to provide information for genetic counsellors to assess the probability of a couple having a child with CF on a newborn baby to confirm other diagnostic tests on an embryo or foetus so parents will know whether their unborn child will have CF so important decisions can be made.

4 How genetic testing is done

How genetic testing is done

Samples of DNA obtained from the nuclei of cells. http://www.ac-creteil.fr/biotechnologies/doc_englishbiomol.htm

5 Summary

Summary

6 How genetic testing is done

How genetic testing is done

Samples of DNA obtained from the nuclei of cells. DNA ‘cut up’ into small fragments using enzymes. DNA strands separated. Specific defective CFTR allele detected by using a specific gene probe (small length of DNA with complimentary base sequence). Gene probe will bind to bases in CFTR allele in a way which enables it to be detected.

7 Genetic testing for CF
8 How genetic testing is done

How genetic testing is done

Obtaining a sample of DNA to be tested. Samples of DNA obtained from the nuclei of cells, so sample of cells required. From cells from a baby or an adult This could be: a blood sample cells from lining of mouth But it is also possible to obtain cells from a developing embryo in the womb.

9 From cells from a foetus

From cells from a foetus

Since baby not yet born, sometimes called prenatal testing Cells of baby obtained by 1: Amniocentesis, usually at 15-17 weeks of pregnancy

10 http://www

http://www

genetics.com.au/factsheet/15.htm Pre-natal testing

11 Needle inserted into amniotic fluid

Needle inserted into amniotic fluid

Sample of amniotic fluid collected

contains cells from placenta and foetus

cells cultured and DNA extracted

12 Limitations of amniocentesis

Limitations of amniocentesis

Carried out quite late in pregnancy Takes several weeks for results to be available so any subsequent termination is more complex surgically and more traumatic for the mother Procedure has a 0.5 – 1% risk of miscarriage

13 2: Chorionic villus sampling Alternative to amniocentesis

2: Chorionic villus sampling Alternative to amniocentesis

14 Transcerivcal CVS

Transcerivcal CVS

http://images.google.co.uk/imgres?imgurl=http://www.americanpregnancy.org/images/lib/sonagram.jpg&imgrefurl=http://www.americanpregnancy.org/prenataltesting/cvs.html&h=200&w=150&sz=10&tbnid=vDb0Sz_C6EkJ:&tbnh=99&tbnw=74&hl=en&start=15&prev=/images%3Fq%3Dchorionic%2Bvillus%2Bsampling%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DG

15 Transabdominal CVS

Transabdominal CVS

Small sample of placental tissue removed (includes cells of the foetus)

DNA extracted

More cells collected so results available in 1 – 7 days

16 Advantages of CVS

Advantages of CVS

Carried out earlier in pregnancy - 8-10 weeks Results available quicker so pregnancy much less established so termination easier and (potentially?) less traumatic to the mother But 1 – 2% risk of miscarriage

17 DNA from an embryo

DNA from an embryo

Sometimes called pre-implantation genetic diagnosis (PIGD) Involves collecting several eggs and in vitro fertilisation to produce several embryos http://www.genetics.com.au/factsheet/16.htm

18 Remove a cell from the embryo at the 8-16 cell stage (a few days old)

Remove a cell from the embryo at the 8-16 cell stage (a few days old)

and test that for the presence of the defective CFTR allele.

Only implant viable embryo without CF mutation to establish pregnancy.

[See video clip activity 2.19?]

19 Advantages No pregnancy to terminate Know that baby will not have CF

Advantages No pregnancy to terminate Know that baby will not have CF

20 Disadvantages Expensive IVF itself expensive and still fairly

Disadvantages Expensive IVF itself expensive and still fairly

unreliable How to decide who gets the treatment since cost prevents its availability to all? Possibility of false negatives What is done with the spare embryos?

21 Q&A: Embryo test http://news

Q&A: Embryo test http://news

bbc.co.uk/1/hi/health/5093970.stm Work by scientists could lead to a non-invasive blood test to detect genetic abnormalities such as Down's syndrome in the womb. Current non-invasive tests - such as ultrasound - are limited, and invasive tests pose a risk to the pregnancy. The new technique works by examining samples of foetal DNA present in the mother's blood for tiny variations in the sequence of the genetic material. http://news.bbc.co.uk/1/hi/health/6320273.stm

22 What options are there if the test is positive for CF

What options are there if the test is positive for CF

What living with CF is like http://news.bbc.co.uk/1/hi/uk_politics/6159935.stm

23 What options are there if the test is positive for CF

What options are there if the test is positive for CF

If pre-implantation don’t implant CF embryo. If pre-natal consider termination (not compulsory!)

24 Why might people choose not to test even if was offered to them

Why might people choose not to test even if was offered to them

If parents believe, for religious or other reasons, that termination is wrong If parents consider the risk of miscarriage too high If parents want to have a child whatever, even if it has cystic fibrosis

25 This type of test could benefit parents who are known to be carriers

This type of test could benefit parents who are known to be carriers

(so at high risk of producing a CF baby) because:

Tests carried out early in pregnancy so there is choice early termintation (less traumatic) if no termination it allows time for preparation for early treatment of baby for parents to come to terms with the issues facing them and counselling to help them cope allows for peace of mind if baby found to be normal

26 If both parents are found to be carriers, what are the options open to

If both parents are found to be carriers, what are the options open to

them?

Decide not to have children; maybe adopt Take the ‘1 in 4 risk’ of child being CF Use IVF and only implant non-CF embryo Have CVS or amniocentesis test once pregnant and terminate if CF Use artificial insemination by donor (who is not a carrier) to avoid the risk Use egg donation (from a non-carrier) to avoid the risk

27 The first UK babies have been born after a pioneering embryo test http

The first UK babies have been born after a pioneering embryo test http

//news.bbc.co.uk/1/hi/health/6144714.stm http://search.bbc.co.uk/cgi-bin/search/results.pl?scope=all&edition=d&q=genetic+testing&go=Search Video clip

28 What diseases can be treated with pre-implantation genetic diagnosis

What diseases can be treated with pre-implantation genetic diagnosis

(PGD)? http://www.bbc.co.uk/sn/tvradio/programmes/horizon/babies_qa.shtml

29 Moral and ethical dilemmas of genetic screening

Moral and ethical dilemmas of genetic screening

Morals are concerned with ‘goodness’ and ‘badness’ or the distinction between what is right and what is wrong. Ethics are moral principles, or a code of behaviour based on morals. http://www.beep.ac.uk/content/313.0.html http://www.ornl.gov/sci/techresources/Human_Genome/elsi/elsi.shtml

30 Positives and Negatives of Genetic Screening

Positives and Negatives of Genetic Screening

Further Info. Media on Demand (need route; start/programs/…. Gene Tech Tapes Pt 4. Genetics and Reproduction. Bioethics website. http://www.beep.ac.uk/content/16.0.html http://www.medic8.com/genetic-testing/index.htm http://royalsociety.org/page.asp?id=1264

31 Positives of Genetic screening

Positives of Genetic screening

Identifies carriers Allows informed decisions whether to have children Enables carriers to get pregnant (previously they may not have taken the risk) but reduces risk of giving birth to baby carrying a genetic disease Embryo test 'offers parents hope' (pre-implantation test for Duchene MD) http://news.bbc.co.uk/1/hi/health/5079802.stm http://news.bbc.co.uk/1/hi/health/5093970.stm

32 Allows early intervention prenatal testing termination If know, can

Allows early intervention prenatal testing termination If know, can

deal with it. Allows a change in life style (e.g. for hypercholesterolaemia and risk of heart disease) to reduce risk e.g. change diet, monitor cholesterol levels etc. In long term may benefit society by reducing costs involved in treatment, support services etc.

33 Identification of genes associated with illness

Identification of genes associated with illness

http://search.bbc.co.uk/cgi-bin/search/results.pl?q=genes+linked+to+illness&scope=all&edition=d&tab=all&recipe=all&x=23&y=12 http://www.newscientist.com/channel/health/dn12006-biggest-ever-haul-of-genes-linked-to-diseases.html

34 Negatives of Genetic screening

Negatives of Genetic screening

Knowledge that at risk could lead to stress, depression (e.g. Huntington’s disease, breast cancer); would you want to know? http://news.bbc.co.uk/1/hi/health/6276656.stm UK scientists have identified a gene they say increases the risk of bowel cancer by 20%. http://news.bbc.co.uk/1/hi/health/7146860.stm Scientists say they have found two genetic mutations which could triple the risk of developing bowel cancer. Cost of screening/use of resources perhaps better used elsewhere? Who decides what genes to test for? Confidentiality; who needs to know? Problems with life insurance (knowledge about genes affects expectancy/premiums etc)

35 A temporary ban on the results of genetic tests being made available

A temporary ban on the results of genetic tests being made available

to insurance companies has been extended by three years. The moratorium which ran out in 2011 will now stand until 2014. It means people seeking insurance do not have to reveal the results of genetic tests which could point to the risk of serious illness in the future. http://news.bbc.co.uk/1/hi/business/7452909.stm

36 Employment Treated differently

Employment Treated differently

Everybody has the ‘right to life’. May lead to more terminations? Baby has no ‘say’ in the decision. http://news.bbc.co.uk/1/hi/uk/4350259.stm http://www.efc.org.uk/Foryoungpeople/Factsaboutabortion/MoreonUKabortionlaw Potential waste of a productive life? Test may indicated the risk of developing a debilitating life-threatening illness later on in life, but what positive things could be done before that? (Mozart, Picasso, Wilfred Owen and many others had remarkable achievements before they reached 30 years of age) Ethics of testing – embryos (i.e. more embryos than needed will be created, those with mutation destroyed- what happens to the rest?

37 Risk of miscarriage of a healthy baby Risk of false negatives so

Risk of miscarriage of a healthy baby Risk of false negatives so

serious decisions based on wrong information (many mutations known to cause CF; only commonest ones are tested for) Private sector exploitation – choice/whim/money; may pay for test if not available of NHS? A company has launched an online service that will enable people to receive a profile of their own genome. http://news.bbc.co.uk/1/hi/sci/tech/7098998.stm Government advisors have called for tighter controls on genetic tests sold directly to the public. http://news.bbc.co.uk/1/hi/health/7121692.stm

38 Further Info

Further Info

Media on Demand (need route; start/programs/…. Gene Tech Tapes Pt 4. Genetics and Reproduction. Bioethics website. http://www.beep.ac.uk/content/16.0.html http://www.medic8.com/genetic-testing/index.htm http://royalsociety.org/page.asp?id=1264

39 Genetic testing for CF
40 Checkpoint 2.7. ethics of genetic screening; Is it or is it not

Checkpoint 2.7. ethics of genetic screening; Is it or is it not

acceptable to terminate a foetus found by amniocentesis to have CF

Rights and duties Every individual born or unborn, has the right to life. Parents have a duty to meet this right. A mother has the right to continue or not with a pregnancy, particularly if the pregnancy presents risks to the mother’s physical or mental health. Parents have the right to make a free and properly informed choice about whether or not to terminate a foetus found to have a genetic disorder

41 Maximising the amount of good in the world Unethical to bring a child

Maximising the amount of good in the world Unethical to bring a child

with a severe genetic disease into the world if this will result in substantial suffering of the individual, greatly reduce the happiness of the family, or drain the financial resources of society Allowing a child with a genetic disease to be born may replace the possibility of a healthy child being born. Selecting healthy children will strengthen, rather than weaken, the gene pool, reducing the number of faulty genes in the population.

42 Making decisions for yourself

Making decisions for yourself

It is up to parents to decider if they are willing and able to have a child that will require a special commitment of care.

43 Leading a virtuous life

Leading a virtuous life

Virtuous parents would perhaps love and care for their child irrespective of their physical or mental capacities. Virtuous relatives and families would help them.

44 An effective genetic screening programme must be

An effective genetic screening programme must be

reliable (with no false positives) inexpensive simple (for the patient) quick in delivering results backed up with good education about the test counselling as a follow-up to the test confidential

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