PGD - Preimplantation Genetic Diagnosis
If you begin investigating the possibility of pregnancy through in vitro vertilization, you will doubtless encounter a term called preimplantation genetic diagnosis (or PGD). This refers to a genetic procedure that is used before the actual implantation in order to assist in identifying defects that are within the embryo that was produced via this laboratory fertilization process.
The procedure also helps to prevent some disorders and disorders from being passed from the parent to the child. Normally, either the male or female has undergone genetic screening and one or both have been found to be carriers. Here's how the PGD process is conducted.
The diagnosis begins with the typical process of in vitro fertilization. This includes stimulation of the ovary through medication; retrieval of the egg; and laboratory fertilization. The embryo then divides into eight cells during the following three days.
The genetic diagnoses will involve these steps: 1) One cell will be taken from the embryo using "pipettes"--small medical instruments designed for this purpose. 2) The doctor will remove DNA from the cell and copy it in a process known as PCR: "Polymerase Chain Reaction." 3) During a molecule analysis, the DNA sequence code will be evaluated in order to see if the gene is inherited.
After the Preimplantation Genetic Diagnosis has been performed, and the medical staff have identified embryos that have no genetic problems, they will attempt embryo transfer, or perhaps ICSI ("intracytoplasmic sperm injection") or ZIFT ("zygote intrafallopian transfer").
Any couple that believes, or has been told, that they are at risk for passing a genetic condition on to a child could possibly benefit from preimplantation genetic diagnosis. Specifically, anyone from one of these groups could be a suitable candidate:
- Those who carry sex-linked gene disorders
- Females who are above age 35
- Those who carry single-gene defects
- Anyone with chromosome disorders
- Any woman who experiences multiple pregnancy losses that have bee attributed to chromosome concerns.
- Also, even though there are ethical controversies with the process, some have used PGD for gender-selection purposes.
During the process of preimplantation genetic diagnosis, the medical staff are looking for chromosome or gene problems which would put the couple at risk for either spontaneous miscarriage or birth defect. PGD will look for any of the following:
- Hemophilia, neuromuscular dystrophies, fragile-X syndrome, or other recessive sex-linked disorders
- Rett Syndrome, pseudohypererp arathydroidism, incontinentia pigmenti, Rickets, or other dominant sex-linked disorders
- Cystic fibrosis, Huntington disease, Tay-sachs, sickle-cell anemia, or other single-gene disorders
- Translocation, deletions, inversion, Aneuploidy, or other chromosome rearrangements.
Some of the benefits of using preimplantation genetic diagnosis include:
- It could reduce the patient's need for amniocentesis that would otherwise occur later during the pregnancy.
- It could let the couple decide whether or not to continue the pregnancy.
- It could allow some couples to try to have biological children, when they otherwise might not have done so.
- It might lower expensis associated with medical complications brought on by birth defects.
If you want to consider preimplantation genetic diagnosis, speak with your physician and he or she will tell you the good and bad points associated with the procedure.