Preimplantation Genetic Diagnosis (PGD)


Preimplantation Genetic Diagnosis (PGD) is a technique that can be used during in vitro fertilization (IVF) procedures to test embryos for genetic disorders prior to their transfer to the patient. PGD makes it possible for couples or individuals with serious inherited disorders to decrease the risk of having a child who is affected by the disease.


PGD was first performed in 1989. It has since been successfully used to screen for a wide variety of genetic diseases, either single gene disorders or chromosomal abnormalities. In single gene disorders where the gene structure is known, such as cystic fibrosis or Tay-Sachs, the actual genes of the sampled embryo can be examined for the presence of the condition. Other genetic conditions, such as Duchenne Muscular Dystrophy or hemophilia, affect only males. In these cases, while the exact gene defect may not be known, the DNA of the biopsied cell can be examined to determine the sex of the embryo and only female embryos transferred during IVF. Finally, in cases of severe recurrent chromosomal diseases, such as Down syndrome (which has an extra chromosome), the number and character of several chromosomes of the sampled embryo can be determined.


Additionally, in patients who undergo multiple IVF procedures which fail to result in pregnancy or who have multiple miscarriages, it is possible that chromosomal abnormalities are responsible for a significant percentage of these failures. The incidence of abnormalities may be increased for women of advanced reproductive age. PGD allows those patients the option to examine the chromosomal health of their embryos before transfer. Generally a phone consultation will be provided by the PGD specialty laboratory chosen to discuss the appropriate testing.


EXAMPLES OF PATIENTS WHO MAY CHOOSE PGD


  • One or both partners are carriers of single gene disorders, such as cystic fibrosis or Tay-Sachs disease.
  • The female patient is of advanced maternal age (> 38 years old), and is at risk for chromosomal aneuploidy such as Down Syndrome.
  • The female patient has a history of repeated spontaneous miscarriages.
  • The female patient has failed to conceive after multiple IVF attempts.
  • The patient or partner may have chromosomal translocations or other chromosomal abnormalities.


HOW IS PGD PERFORMED?


Embryos are obtained through IVF, usually combined with Intra Cytoplasmic Sperm Injection (ICSI). Once the embryo(s) has been allowed to grow to approximately 5 to 7 days old, several cells (2-5) are removed from each embryo under microscopic guidance, and the cells are sent to a specialty laboratory to analyze them for the presence of the specific genetic disorders. A diagnosis is obtained, and only the embryos showing no genetic defects are considered for transfer to the female patient. There are charges for the services performed by Virginia IVF and Andrology Center for both the biopsy and shipping done during the PGD process. The laboratory selected for PGD will charge separately for their services.



For more information, please visit:
American Society For Reproductive Medicine