Preimplantation genetic diagnosis (PGD), the genetic testing for chromosome abnormalities, is becoming increasingly popular and is used in conjunction with in vitro fertilization (IVF). IVF is the process of mixing egg cells with sperm to be fertilized outside of the womb.
The performance of this type of testing (PGD) may increase the chance for a successful pregnancy, especially for those women who experienced several miscarriages, when either of the parents have a genetic abnormality or disease, with a family history of an illness or genetic predisposition, or when women are over the age of 35.
How a Diagnosis is Made
Three different techniques are used to test the embryo for genetic abnormalities. With the PCR (polymerase chain reaction) technique, there is the allowance for multiplication (DNA) testing for which mutation can be detected from one single gene. It usually takes about one day to get the results from the test. Once the procedure is finished, the embryos are kept in a growth media to allow for further division. After the diagnosis is done, the other unaffected embryos can be placed back into the uterus for the in vitro fertilization treatment.
With the FISH (fluorescent in situ hybridisation) technique, specially chosen fluorescent probes are used to test the chromosomes for genetic abnormalities. Labeled probes and glowing molecules will attach themselves to certain chromosomes. This method is used to identify the sex to investigate the linking of certain sexually determined diseases.
Preimplantation Genetic Haplotyping (PGH) was developed in 2006. It uses the DNA profile and makeup (DNA fingerprinting) to screen for genetic diseases. Preimplantation genetic heliotyping can be used when the specific mutation is unknown, or the origin or nature cannot be distinguished.
Duration of Process
Usually a treatment cycle will take about eight to nine weeks, but because of the many tests and preparation, the preimplantation genetic diagnosis usually begins in approximately one year.
