Preimplantation genetic diagnosis (PGD) is a procedure used prior to implantation to help identify genetic defects within embryos created through in vitro fertilization to prevent certain diseases or disorders from being passed on to the child.
How is the PGD performed?
Preimplantation genetic diagnosis begins with the normal process of in vitro fertilization that includes egg retrieval and fertilization in a laboratory. Over the next three days the embryo will divide into eight cells.
Preimplantation genetic diagnosis involves the following steps:
- First, one or two cells are removed from the embryo.
- The cells are then evaluated to determine if the inheritance of a problematic gene is present in the embryo.
- Once the PGD procedure has been performed and embryos free of genetic problems have been identified, the embryo will be placed back in the uterus, and implantation will be attempted.
- Any additional embryos that are free of genetic problems may be frozen for later use while embryos with the problematic gene are destroyed.
Who can benefit from PGD?
Preimplantation genetic diagnosis can benefit any couple at risk for passing on a genetic disease or condition.
The following is a list of the type of individuals who are possible candidates for PGD:
- Carriers of sex-linked genetic disorders
- Carriers of single gene disorders
- Those with chromosomal disorders
- Women age 35 and over
- Women experiencing recurring pregnancy loss
- Women with more than one failed fertility treatment
PGD has also been used for the purpose of gender selection. However, discarding embryos based only on gender considerations is an ethical concern for many people.
What are the benefits of PGD?
The following are considered benefits of PGD:
- PGD can test for more than 100 different genetic conditions.
- The procedure is performed before implantation thus allowing the couple to decide if they wish to continue with the pregnancy.
- The procedure enables couples to pursue biological children who might not have done so otherwise.
What are the concerns of PGD?
The following are considered concerns or disadvantages associated with the use of PGD:
- Many people believe that because life begins at conception, the destruction of an embryo is the destruction of a person.
- While PGD helps reduce the chances of conceiving a child with a genetic disorder, it cannot completely eliminate this risk. In some cases, further testing is needed during pregnancy to ascertain if a genetic factor is still possible.
- Although genetically present, some diseases only generate symptoms when carriers reach middle age. The probability of disorder development should be a topic of discussion with the healthcare provider.
- Keep in mind that preimplantation genetic diagnosis does not replace the recommendation for prenatal testing.