Preimplantation genetic testing is a procedure which can be done during IVF. A few cells are removed from embryos and tested for genetic or chromosomal disorders. These tests can also determine the sex of the embryo. Preimplantation genetic diagnosis(PGD) tests for specific genetic disorders which can be inherited. Most of these disorders require that both parents be carriers of a genetic mutation for the same gene. Some of these disorders are sex-linked, so it becomes important to determine the sex of the embryo before transferring it to the female partner.
PGD is not performed routinely, but may be used when one or both potential parents have significant heritable disorders or when one or both partners carries a chromosomal abnormality., By performing PGD, only unaffected embryos will be transferred to the female partner, making sure that the genetic disorder will not be passed on to the child.
Preimplantation genetic screening(PGS) is a test for chromosomal disorders such as Down Syndrome which are caused by an abnormal number of chromosomes. It doesn’t screen for specific disorders but screens the embryo for a normal number of chromosomes. Often when a woman conceives an embryo with an abnormal number of chromosomes she will miscarry, but in some cases the baby may survive and be born with developmental problems and birth defects. Chromosomal problems are more likely to happen as a woman gets older and her eggs age. PGS can also determine the sex of an embryo,so some fertility clinics offer it for non-medical reasons such as family balancing.
False positives and false negatives are possible with either test. If you or your partner have a history of genetic disease, your physician or genetic counselor will help you decide if further testing is needed, such as amniocentesis or chorionic villus sampling (CVS).
Some people may object to genetic testing due to their religious beliefs. People with religious beliefs that may impact on their fertility treatment should find a fertility center which understands their beliefs and will work with them to find the best solution for them.