Funding to screen for serious genetic conditions
Funding will be made available to allow high-risk couples to screen embryos for serious genetic conditions, Health Minister Pete Hodgson announced today.
Preimplantation Genetic Diagnosis (PGD) is a procedure only used with in vitro fertilisation (IVF) to test early human embryos before they are transferred to a woman's uterus. The procedure is sought by couples at high risk of having children with a serious inheritable genetic condition such as haemophilia or cystic fibrosis.
"For some couples the chance of serious genetic conditions has meant that becoming parents has been too risky," Pete Hodgson said. "Up until now, these couples have had to get pregnant first and test the developing foetus for disorders later. This causes significant stress.
"By testing first and ensuring that embryos with serious genetic disorders are not implanted, we can make it much easier for these couples to have healthy children.
"The screening is expensive – one cycle of PGD costs around $12,000. Public funding is essential to ensure fair and equitable access."
Public funding for the full cost of up to two cycles of IVF/PGD will be available to people who use PGD to test for serious inherited genetic disorders. This funding includes the costs of the IVF treatment that must accompany PGD. The total public investment will be around $500,000 per year.
PGD may also be used to detect chromosome disorders associated with advanced maternal age or infertility, although this use of the screening will not attract public funding. The Ministry of Health expects nearly 150 cycles of IVF/PGD to be carried out in New Zealand each year, of which 40 will be to detect serious inheritable genetic diseases.
People who wish to use PGD should in the first instance see their general practitioner. The funding will be available through district health boards beginning in the first half of 2006.
Questions and Answers
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
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.
What is PGD used for?
Currently, PGD can be used for three different types
- 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.
- Specific approval from the Ethics Committee on Assisted Reproductive Technology will be required where PGD is used for tissue typing (the use of placenta cells from a second sibling to assist an existing child with a disorder).
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 because of advanced maternal age or infertility.
How do I get PGD?
In the first instance, you should approach your general practitioner.
Public funding for the full cost of up to two cycles of IVF/PGD will be available to people who use PGD to test for serious inherited genetic disorders. This funding includes the costs of the IVF treatment that must accompany PGD.
What support is available to me if I am intending to use PGD?
Everyone seeking PGD for familial disorders must receive genetic and psychosocial counselling from appropriately qualified counsellors.
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:
- 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
- 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. Patients who undergo PGD in New Zealand are advised to consider the option of prenatal diagnosis.
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.
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.