Guidelines for genetic testing of human embryos
15 March 2005
Guidelines for genetic testing of human embryos approved
Fertility clinics will be able to test human embryos for serious inherited genetic disorders under new guidelines developed by the National Ethics Committee on Assisted Human Reproduction (NECAHR).
The Guidelines on Preimplantation Genetic Diagnosis (PGD) have been approved by the Minister of Health.
PGD is a procedure used in conjunction with in vitrofertilisation (IVF) to test early human embryos for serious inherited genetic conditions and chromosomal abnormalities before they are transferred to a woman's uterus. The procedure is sought by both fertile and infertile couples at high risk of having children with a serious genetic condition.
The guidelines were finalised after NECAHR undertook wide public consultation. Written and oral submissions were received from fertility clinics, district health boards, professional organisations, consumer groups, government agencies, and individuals with an interest in the subject.
NECAHR Chair, Professor Sylvia Rumball says "The guidelines set clear criteria to ensure this technology is not misused. Use of PGD for non-medical reasons will be prohibited. It is not about 'designing babies', the aim is to help people with serious genetic disorders have children without the risk of passing on an inherited condition."
Currently the only testing option available to couples in New Zealand at risk of passing on a genetic disorder to their child is prenatal diagnosis. PGD offers another choice to carriers of a serious genetic disorders and involves making decisions about the future of an affected embryo, rather than an affected fetus.
Professor Rumball says "Fertility clinics will need to gain approval from NECAHR to offer PGD to patients. Once that's been granted they will be able to use PGD to test for disorders such as Haemophilia and Cystic Fibrosis, as long as the clinics ensure that each case meets criteria set out in the Guidelines."
"In accordance with the Human Assisted Reproductive Technology Act 2004, use of PGD for social reasons, including sex selection, altering the genetic constitution of an embryo, and selecting embryos that have a genetic abnormality seen in a parent are prohibited under the Guidelines" said Professor Rumball.
Fertility clinics given approval to carry out the procedure will have to submit annual reports to NECAHR detailing the numbers of procedures, specifically what they were for, the outcome of the procedure, any ethical issues that may have arisen, and any issues that could have long-term impact on the offspring and their family.
The Minister of Health will be considering public funding of PGD against other priorities within the Health budget.
The Guidelines on Preimplantation Genetic Diagnosis are available on the NECAHR website http://www.newhealth.govt.nz/necahr/
What is Preimplantation Genetic Diagnosis (PGD)?
PGD is a procedure used to test early human embryos for serious inherited genetic conditions. It can only be used in conjunction with in vitro fertilisation (IVF). IVF involves the collection of oocytes from a woman and sperm from a man, and the subsequent creation of an embryo outside the body for implantation into the women's uterus.
How is PGD performed?
PGD involves several steps:
· the creation of an embryo via IVF · the removal of one or two cells from the embryo · the genetic testing of these cells for specific genetic conditions · the subsequent transfer of unaffected embryos to a woman’s uterus.
Why have guidelines for PGD been created?
In 2003 the Minister of Health gave approval in principal to PGD and requested that the National Ethics Committee on Assisted Human Reproduction (NECAHR) develop guidelines on PGD for fertility clinics. The Guidelines for Preimplantation Genetic Diagnosis in New Zealand will help fertility clinics offer PGD to their clients in a safe and ethical manner.
What is PGD used for?
Currently, PGD can be used for three different types of abnormalities:
· single gene defects which cause disorders such as cystic fibrosis or Huntington's disease · numerical chromosomal abnormalities (aneuploidy) which cause disorders such as Down syndrome (an extra chromosome 21) or Turner’s syndrome (females with one X-chromosome instead of two) · structural chromosomal abnormalities such as various forms of translocations.
Who may want to use PGD?
PGD can be used by both fertile and infertile couples. Couples who are carriers of a familial single gene disorder may wish to access PGD to have children without the particular genetic disorder. PGD for aneuploidy screening can also be used for couples who are having trouble conceiving.
What are the potential benefits of PGD?
PGD offers people at high risk of transmitting a serious genetic condition to their children an alternative to their existing options of:
· avoiding conception · attempted natural conception, involving a known risk to the health of the future child · attempted natural conception, and pregnancy termination if the fetus is found to be affected by the condition following prenatal diagnosis · using donated gametes or embryos in an attempt to conceive an unaffected child.
For many people, termination following prenatal diagnosis is either unacceptable or less preferable because of:
· ethical concerns based on beliefs about the moral status of the fetus · emotional trauma associated with a termination, following a much desired pregnancy · health risks associated with possible repeated terminations.
What are the concerns associated with the use of PGD?
PGD can only be used in conjunction with IVF. The live birth rate for PGD is 20-30% per IVF cycle, which is similar to the live birth rate for IVF in the United Kingdom. Despite the relatively wide acceptance of PGD in the clinical arena, it remains a technically demanding procedure. It is subject to a risk of contamination and misdiagnosis, particularly when it is used for single-gene disorders. PGD involves the use of highly technical molecular biology techniques, the accuracy of which ranges from 96-99% depending on the type of test used. While PGD is diagnostically reliable, most European PGD clinics still advise their patients to undergo prenatal diagnosis to ensure that the preimplantation diagnosis is accurate and to test for any abnormalities not screened for during PGD.
Although many overseas PGD clinics offer aneuploidy screening to couples having trouble conceiving or carrying a baby, no consistent evidence is available to show that aneuploidy screening improves the live birth rate for couples having fertility problems.
What are the ethical issues associated with PGD?
Discarding affected embryos
PGD involves making a decision about the fate of affected embryos at a very early stage of development. This is in contrast to prenatal diagnosis, which requires a decision to be made about terminating an existing pregnancy at a much later stage. For many people, discarding embryos is likely to be ethically less problematic than terminating a fetus. For others, both abortion and PGD may be unacceptable.
PGD and disability
Some people suggest that PGD discriminates against people with disabilities, and promotes the view that the birth of people with disabilities should be prevented. However, others contend that it is important to distinguish between ‘disability’ and ‘people with disabilities’, and that selecting against embryos with disabilities does not necessarily imply that those with disabilities are living lives that are less valuable or less meaningful.
Equity and access
Throughout the world PGD is an expensive procedure and concerns have been raised that the technology will be available only to the wealthy. Different jurisdictions have taken various approaches to public funding of PGD, with some governments not funding the service at all. Publicly-funded access to PGD in New Zealand will be considered by the Minister of Health against other priorities within the Health budget.
PGD for Human Leukocyte Antigen tissue typing
Human Leukocyte Antigen (HLA) tissue typing or tissue matching is an additional step to PGD to determine if an embryo could lead to the birth of a child who is a tissue match for an ill sibling.
For some people, HLA tissue typing raises many ethical and social questions. One of the most significant issues is whether people should be able to select an embryo on the basis that the child born may be the source of life saving therapies for a sibling. Under the PGD guidelines, any application for PGD with HLA tissue typing would need to be submitted to NECAHR for ethics approval.
Can PGD be used to select the sex of a baby?
Yes. The use of PGD for sex selection is carried out for two major reasons. The first is to prevent transmission of sex-linked genetic conditions such as haemophilia and Duchenne’s muscular dystrophy, when a specific test for the condition is not available. This medically-based rationale is acceptable to most.
The second reason, a social one, is to provide parents with a child of the preferred sex. This is seen as less acceptable for a number of reasons. Sex selection is seen as a demeaning reason for creating and discarding human embryos, in that it challenges the special status frequently bestowed upon them in view of the potential they represent. Sex selection for social reasons is prohibited by the PGD guidelines and by the Human Assisted Reproductive Technology Act 2004.
Can PGD be used to ‘design’ babies?
In principle, PGD can be used to select for or against any characteristic that has a genetic origin. Some contend that PGD could be used to select against homosexuality, obesity, or hyperactivity, or for intelligence, beauty, or athletic ability. However, the use of PGD for these purposes is not currently scientifically possible.
The guidelines for PGD provide protection against potential misuse of the technology by prohibiting the use of PGD for non-medical reasons. In addition, the guidelines allow PGD to be carried out only in specific circumstances where there is a high risk of serious abnormality.
For some, any selection of embryos is regarded as leading to designer babies. However, PGD does not allow people to determine the precise characteristics of embryos. The selection of embryos prior to implantation via PGD is selection from existing options rather than the design of babies.
Is PGD available overseas?
PGD was first carried out in 1990 for a couple at risk of having a child with cystic fibrosis. Internationally, PGD is employed clinically, and is available to those people who meet the required criteria, in a number of countries, including the United Kingdom, Australia, USA, Canada, Denmark, France, Belgium, Hungary, Sweden, Greece and Spain.
When will the guidelines be reviewed?
The guidelines will be reviewed no later than 2007.