Preimplantation genetic diagnosis is the term used by physicians to describe molecular genetic testing. This involves research into hereditary diseases or abnormalities in the chromosomes of embryos created through artificial insemination.
What is preimplantation genetic diagnosis?
Preimplantation genetic diagnosis (PGD) is medical research performed on embryos conceived through artificial insemination. Preimplantation genetic diagnosis (PGD) is medical testing performed on embryos conceived through artificial insemination. The embryos are only a few days old and are examined before their transplantation into the female uterus takes place. In this way, doctors are able to detect, among other things, defects in chromosomes that pose a risk of miscarriage or stillbirth. The parents can then decide whether or not to have the transplant in the uterus. Preimplantation genetic diagnosis is one of the most controversial medical procedures. Although the method has been used since the 1990s, it has only been approved in Germany since 2011.
Function, effect, and goals
Preimplantation genetic diagnosis is used to detect genetic changes that provide evidence of serious diseases in the unborn child. In this process, the genetic material of artificially fertilized eggs is checked for chromosomal abnormalities and hereditary diseases. However, the prenatal diagnostic method is only performed in risk groups where there is a suspicion of a genetic disease. This may be the case, for example, if Huntington’s disease has already occurred several times within a family. There is also the possibility that the woman has already had several failed artificial inseminations (in vitro fertilization). However, the results of pre-implantation diagnostics are not always absolutely certain. Thus, in rare cases, misdiagnosis is quite conceivable. To confirm the diagnosis, additional prenatal diagnostics (PND) can be performed, such as a chorionic villus sampling or amniocentesis. Genetic diseases for which preimplantation genetic diagnosis is useful include primarily Huntington’s disease, sickle cell anemia, cystic fibrosis, beta-thalassemia, and Marfan syndrome. Other disorders include Pätau syndrome (trisomy 13), Edwards syndrome (trisomy 18), monosomy 21 and Duchenne type muscular dystrophy. In the meantime, PGD is not only limited to the detection of approximately 200 hereditary diseases. It also serves to increase the success rate of artificial insemination and to select the sexes, whereby there does not necessarily have to be a disease connection. In addition, preimplantation genetic diagnosis also identifies diseases that can be examined in the course of prenatal diagnostics, but for which no diagnosis is usually made. The most common application of PGD is aneuploidy screening. This is increasingly used in infertile couples who are already at an advanced age and who have already had several unsuccessful attempts at in vitro fertilization or miscarriages. The aim of preimplantation genetic diagnosis is to eliminate the embryos responsible for the problems that have occurred. In this way, the chances of success in having a healthy child can be increased. In some countries, PGD is also used to identify so-called savior siblings. This refers to embryos that can help older siblings suffering from a serious disease by donating umbilical cord blood or bone marrow. For this purpose, preimplantation genetic diagnosis selects suitable tissue characteristics following artificial insemination. For preimplantation genetic diagnosis to take place, artificial insemination must first take place. This results in the creation of several embryos. Fertilization of the female oocytes with the male sperm is performed outside the body. After the eggs are extracted from the woman’s organism, they are developed into embryos in a test tube. About three days after fertilization, one or two cells can be removed and examined as part of preimplantation genetic diagnosis, for which various techniques are used.
Risks, side effects and dangers
Preimplantation genetic diagnosis is always associated with the risks associated with artificial insemination.Thus, side effects such as pain, breathing difficulties, nausea, and blood clotting disorders may occur during this significant procedure. In addition, one complication must be expected, which is more common with artificial insemination in connection with PGD than with other procedures. This is ovarian hyperstimulation syndrome (OHSS). It is divided into mild and severe forms. In the severe forms, there is sometimes even a danger to life. In principle, the woman receives numerous hormones during artificial insemination in order to mature the eggs in the ovaries. In the case of preimplantation genetic diagnosis, the amount of hormones must be even higher than in the case of simple test tube fertilization without PGD. However, this poses the risk of overstimulation of the ovaries, which is manifested by their severe enlargement. Cysts develop within the ovaries and the circumference of the abdomen increases. In some affected women, fluid may also accumulate in the abdominal region. In addition, the blood increases in viscosity, which in turn causes circulatory problems in the kidneys. As a result, there is a risk of dangerous renal insufficiency. Preimplantation genetic diagnosis is a procedure that has been the subject of heated controversy around the world for many years. The discussions raise fundamental ethical and political questions about the value of life. Critics accuse PGD of not accepting social diversity. Moreover, it increases the pressure on parents to have healthy children at all costs. The approval of preimplantation diagnostics in Germany would damage the values of the Basic Law on the right to dignity. Proponents of PGD, however, see the procedure as an opportunity to spare couples and their children serious hereditary diseases.
