Some clinics offer screening for over 400 hereditary conditions that are being tested by the preimplantation genetic diagnosis method. Some medical professionals utilize this procedure to increase the rate of success for in vitro fertilization treatments and pregnancies, and to rule out predisposition to disease.
About In Vitro Fertilization
In vitro fertilization (IVF) is a clinical procedure and fertility treatment process by which the egg cells are mixed with male sperm in a dish. Once the eggs are fertilized, they are then placed into the woman's uterus for a healthy pregnancy to take place. The difference from a normal pregnancy is that the eggs are fertilized outside of the womb.
Medical studies indicate a higher cancer risk for children who were conceived through in vitro fertilization treatment, with leukemia and brain cancers the most common ones. The reason is not because of the procedure itself, but because test tube children are born prematurely which raises the risks, and parents who seek this type of fertility treatment often have a genetic predispostion to the disease and cancer already.
Preimplantation Genetic Diagnosis
A preimplantatiion genetic diagnosis can detect any genetic defects in embryos before they are implanted into the womb. This test is often done when one or both of the parents planning to conceive have a genetic abnormality, or if there is a disposition to a specific disease or genetic abnormality in the family. The embryos can be screened beforehand to see if the gene is detected.
Reasons to Choose Preimplantation Genetic Diagnosis
Many women select this type of procedure in conjunction with in vitro fertilization treatment, because this method of testing can be performed with advanced aging, and wanting to conceive without the more complicated risks. This option may be considered for women wanting a pregnancy later in life, after the age of 37, or for those that experienced several miscarriages or who failed to conceive with frequent attempts of in vitro fertilization. Healthy embryos can be frozen for later use.
Preimplantation Genetic Diagnosis is successful at predicting genetic disorders and diseases before a baby is born, but it cannot guarantee a healthy child. The process is complex, and medical studies indicate that results may not always be correct.
Ethical implications can arise with this type of embryo cell testing. These could include sex selection, medical benefit for the wealthy, disapproval from religious denominations, the "designer baby," misuse and the possibility of error.
How Preimplantation Genetic Diagnosis Is Performed
After the initial preparation and testing such as the stimulation of the ovaries with fertility medications, sperm washing to increase male fertility, cryopreservation for the collecting and freezing of the sperm for a future date, and the retrieval of the healthy sperm (swim-up technique), the preimplantation genetic diagnosis can be performed.
On the third day of in vitro fertilization, an embryo biopsy is performed. A laser or glass needle can be used to puncture the shell of the external layer of the embryo (zona pellucida) or with the use of a laser.
By gentle suctioning, a single cell (single blastomeric) is retrieved from an 8-cell embryo, for which the sample is then sent to a laboratory where preimplantation genetic diagnosis and genetic testing is performed through different techniques.