All you need to Know about PGD
What is PGD
Pre-implantation genetic diagnosis (PGD) enables people with an inheritable condition in their family to avoid passing it on to their children. It involves checking the genes and/or chromosomes of embryos created through IVF.
Possible candidates
- Carriers of sex-linked genetic disorders
- Carriers of single gene disorders
- Those with chromosomal disorders
- Women age 35 and over
- Women experiencing recurring pregnancy loss
- Women with more than one failed fertility treatment
Benefits of PGD/PGS at a glance
- Genetic testing such as reimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS) can help detect known genetic diseases or chromosomal abnormalities.
- Identifies abnormal embryos, preventing unhealthy embryos from being transferred to uterus.
- Reduces multiple pregnancy risk by identifying healthy embryos for implantation.
- Decreases risk to couples or individuals with serious inherited disorders of having children affected with same problem.
Risks
- PGD and PGS require in vitro fertilization (IVF), which involves risks of ovarian hyperstimulation syndrome, multiple pregnancy, and increased risk of birth defects not related to the genetic test.
- Risk of biopsy or freezing harming the embryo(s).
- False negative results could mean an abnormal embryo is transferred to the uterus, resulting in a possible miscarriage, and healthy embryos are discarded, limiting chances of a healthy pregnancy.
- Test could reveal there are no normal embryos to transfer.
- Tests do not screen for all possible genetic diseases or disorders, so a healthy baby is not guaranteed from a tested embryo.
Most of the risks involved in PGD treatment are similar to those for conventional IVF:
- Fertility drug reaction: mild reactions may involve hot flushes, feeling down or irritable, headaches and restlessness; symptoms usually disappear after a short time.
- Multiple pregnancy: risk of complications is higher in a pregnancy with twins or multiples (although some centres reduce this risk by only transferring one embryo).
- Ovarian Hyperstimulation Syndrome (OHSS): Symptoms include abdominal pain and swelling, shortness of breath, nausea, vomiting, and a reduction in urine output; can result in mineral imbalances in the blood and clotting problems.
- Pelvic infection.
- Miscarriage: risk of a miscarriage after IVF is no higher or lower than after a natural conception.
- Ectopic pregnancy: pregnancy development in the fallopian tubes instead of the womb. This would not result in an ongoing pregnancy.
Risks to babies born following PGD
No strong evidence currently exists to suggest that babies conceived through this process are at any greater risk of abnormality than babies conceived through other forms of assisted reproduction.
Several studies have concluded that there do not appear to be any major side-effects to the PGD treatment. However, there is evidence that babies conceived through IVF are more likely to:
- be born prematurely
- weigh less than naturally conceived babies born at the same age
less common in young women, PGS is generally not used with donor eggs.
In summary regarding PGD for aneuploidy screening
- A high percentage of human embryos are chromosomally abnormal.
- PGS technology allows us to biopsy IVF embryos and test for chromosomal normality.
- Day 3 embryo biopsy and PGS using FISH technology reduces IVF success rates.
- There is recent evidence from multiple studies that trophectoderm biopsy and PGS using one of the newer genetics technologies (aCGH, SNP or qPCR) increases IVF success rates.
- Prospective randomized trials of no PGS vs. PGS for aneuploidy using trophectoderm biopsy in conjunction with these new genetics technologies are needed.
Cost of PGD and PGS
Another issue with PGS and PGD is cost. Over the years the cost has been dropping, but it is still expensive technology.
- The biopsies and tests, in the USA, cost from about $4000-$9000 plus all other associated IVF costs.
- There will often need to be a frozen embryo transfer cycle done after PGD or PGS testing.
- There are costs associated with the embryo biopsy procedure itself and there are costs for the genetics laboratory performing the genetic studies on the cells.
- The cost performing PGD in Iran is much lower (almost 0.25 that oh the USA)
Sources
hfea.gov.uk, American Society for Reproductive Medicine. (2014). Preimplantation genetic testing, arm.coloradowomenshealth, geneticalliance.org.uk, arm.coloradowomenshealth.com, Chromosome Screening. (n.d.). Single gene PDG: Helping carriers of single gene disorders have a successful pregnancy and a healthy baby, Penn Medicine. (n.d.) Preimplantation genetic diagnosis (embryo screening), advancedfertility.com,
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