Pre-implantation genetic diagnosis (PGD)

Pre-implantation genetic diagnosis (PGD) is a technique that involves checking the genes of embryos created through IVF for any kind of serious genetic defects. This method allows people with a specific inherited condition in their family to avoid passing it on to their children. In most cases, the female, male, or both partners have been genetically screened and identified to be carriers of potential genetic conditions.

Ideal Candidates for PGD

Genetic testing of embryos is recommended for:

• Women above the age of 35
• Those who have a family history of a serious genetic disorder
• Women who have had a number of abortions because your baby had a genetic condition
• Those who already have a child with genetic defects
• Carriers of sex-linked genetic disorders
• Carriers of single gene defects
• Those with chromosomal disorders

PGD Procedure

Normal IVF treatment is carried out which involves collecting and fertilizing the eggs. The resulting embryo is grown in the laboratory for a couple of days to allow for the division of cells until there are about 8 cells (also called as blastomeres). A well trained embryologist then removes one or two blastomeres from the embryo which are tested to check if they contain the gene that causes the genetic condition in the family. Embryos which do not contain the defective gene are transferred to the womb to allow them to develop while those affected by the genetic condition are allowed to perish. Any suitable remaining unaffected embryos can be frozen for later use upon request. Two weeks after the embryo transfer, the patient is advised to undergo a pregnancy blood test.

Advantages of PGD

The advantages of PGD include:

• As this technique is performed before implantation, it eliminates the need for procedures like amniocentesis later on during pregnancy.
• It allows couples to have biological children who might not have done this choice otherwise.
• This technique helps reduce costs normally associated with birth defects and their treatments.

Disadvantages of PGD

Disadvantages associated with PGD include:

• While PGD helps minimize the chance of conceiving a child with a genetic condition, it does not completely eliminate the risk. In certain cases, further testing during pregnancy is necessary to check if the defective genetic factor is still present.
• Although genetically present, some resulting diseases only show symptoms when carriers reach middle age.
• In certain cases, a genetically defective fertilized egg will mature without the presence of disorder or disease.