PGD - PREVENTING GENETIC DISEASE
If you have a history of genetic defects in your family, or if you have experienced recurrent miscarriages, you may be interested in trying preimplantation genetic diagnosis(PGD). PGD offers many couples the hope of having a child that is unaffected by genetic mutations or chromosomal abnormalities. PGD testing can help to determine the health of your embryo before it is implanted during your fertility treatments. This can help to increase the chance of carrying a healthy pregnancy to term.
What is Preimplantation Genetic Diagnosis?
PGD is a testing procedure used to detect unhealthy embryos before they are transferred to your womb during IVF treatment. Developed in the 1980s, PGD testing is used to detect problems with specific genes or chromosomes in embryos.
During the early stages of embryo development, cells from your embryos are analyzed for genetic abnormalities. By detecting gene problems before implantation, unhealthy or defective embryos can be discarded, allowing only healthy embryos to be implanted during fertility treatments.
Who Uses Preimplantation Genetic Diagnosis?
Preimplantation genetic diagnosis is still a fairly new fertility treatment. It is only available in large fertility clinics and is offered to couples with a history of genetic disorders and other life-threatening diseases. Many couples are reluctant to give birth to a child for fear of passing on a dangerous genetic defect. Genetic disorders can often impact greatly on a person’s life, causing physical and emotional pain, developmental problems, and even death. PGD is intended to help prevent a couple from passing on these genetic defects to their child.
In particular, couples who pursue PGD testing tend to fall into one of three categories:
- Those with a single gene defect, which often manifests as a family history of genetic disorders.
- Those with chromosomal defects.
- Those with chromosomal rearrangement, in which multiple miscarriages are often experienced.
What Conditions Can Preimplantation Genetic Diagnosis Detect?
Researchers can now screen specific chromosomes for certain diseases, including:
- Chromosome X: Duchenne muscular dystrophy, Fragile X Syndrome, and Turner's Syndrome
- Chromosome Y: Acute myeloidleukemia
- Chromosome 13: Wilson Disease, breast cancer, ovarian cancer
- Chromosome 15: Tay-Sach's Disease, Marfan Syndrome
- Chromosome 16: Alpha thalassemia, Polycystic kidney disease
- Chromosome 17: Charcot-Marie-Tooth Disease
- Chromosome 18: Pancreatic cancer, Niemann-Pick Disease
- Chromosome 21: Down's Syndrome
- chromosome 22: Chronic myeloid leukemia
The Benefits of Preimplantation Genetic Diagnosis
There are a number of benefits to using PGD. If you already have a child with a genetic disorder, PGD testing can prevent you from passing the genetic defect on to another child. PGD testing can help to limit the number of implantation failures and spontaneous abortions you experience, as it prevents the use of unhealthy embryos. PGD can also help to limit your chances of having twins or higher-order multiples.
Disadvantages to Pre-Implantation Genetic Diagnoses
There are some drawbacks to using PGD testing to conceive a child. PGD testing requires the use of in-vitro fertilization, which is not associated with the best pregnancy success rates for all couples. PGD testing also conflicts with some people’s religious or moral views. Because some embryos will be destroyed, you may feel uncomfortable with the idea of using PGD testing to conceive.
The PGD technique is a fairly complex procedure that demands the skills of a highly qualified reproductive endocrinologist. PGD testing can only be performed when a couple elects to use IVF. PGD testing can usually be performed relatively quickly, in order to ensure timely implantation of all healthy embryos.
The PGD testing procedure does involve a number of steps:
- You will be treated with fertility drugs, such as Clomid, to induce ovulation.
- Once you have ovulated, some of your eggs will be retrieved for fertilization.
- In your clinic’s laboratory, your eggs will be fertilized with your partner’s sperm.
- After about three days, or once your embryo has developed to between 6 and 12 cells, PGD testing can begin.
- A small hole is made in the outer layer of your embryo.
- One of your embryo’s cells is removed. This will not affect the development of your embryo.
- DNA is extracted from the nucleus of the cell. This is then analyzed using a procedure called polymerase chain reaction (PCR) for any genetic defects.
- Any unhealthy embryos may be discarded, while the remaining healthy embryos are implanted in your uterus.
Costs of Pre-Implantation Genetic Diagnosis
Unfortunately, because it is so complicated and not widely available, PGD is very expensive. You will have to undergo in-vitro fertilization procedures, which generally run upwards of $12,000. PGD testing can be combined with IVF for between $2,500 and $4,000. These procedures are generally not covered by medical insurance.