One of the ways of eliminating hereditary disorders is through Pre-implantation Genetic Testing (PGT). The test assesses overall chromosomal normalcy in embryos. It is an innovative test that determines if an embryo is chromosomally normal and therefore more likely to implant in the uterus during an IVF cycle. It can also look at the genetic composition of the embryos to make sure it is not carrying a known gender disorder.
The basis of PGT relies on the fact that all of an embryo’s cells contain the same genetic information and can therefore identify defects. Such genetic defects include a missing or an extra chromosome in the embryo, such as in Down Syndrome mental retardation. Other detectable defects include errors in the sequence of proteins in the DNA which can lead to diseases like sickle cell etc.
There are certain diseases that run in families to screen for and this technology has made it possible to identify embryos that can bear some
diseases so that such embryos can be eliminated.
It examines embryos during IVF before possible transfer to a woman’s uterus for a range of genetic problems that can cause implantation failure, miscarriage, and birth defects in the yet-to-be-born child.
Some parents that opt for PGT themselves have a genetic disorder. Certain disorders can make it difficult for parents to conceive or carry a pregnancy to full term. Others lead to life-threatening conditions later in life.
Some people who do not use PGT are at an increased risk of having a child with a genetic disorder. Increased risk can come about for multiple reasons.
Among these are women over age 35 that have a higher chance of having a child with too many or too few chromosomes (aneuploidy). Some people are carriers of genetic disorders, even though they are healthy.
Those that are carriers are at risk of having a child with a life-threatening disease. Often, carriers would be able to conceive naturally, but they choose IVF because it allows for genetic testing of the embryos—specifically, preimplantation genetic diagnosis.
Preimplantation genetic testing is done when a fertilized egg has developed to reach the day 5 embryo stage. Genetic testing is done on the embryonic cell or cells that are removed. The rest of the cells are allowed to continue developing.
Humans are designed to have 23 pairs of chromosomes, inheriting one copy of each chromosome from either parent. However, sometimes embryos are formed with too many or too few chromosomes, which is known as aneuploidy. Embryos with aneuploidy may be born with conditions like Down syndrome or Trisomy 21.
In other cases, aneuploidy results in a miscarriage. There are also translocations, in which parts of chromosomes break off and change places
with another chromosome.
Essentially, PGT can determine if an embryo has the correct number of chromosomes to develop into a viable pregnancy and a healthy baby. Not only does PGT allow physicians to be assured with a high degree certainty that an embryo has the correct number and balance of chromosomes, it also allows our fertility specialists to transfer only one embryo at a time, decreasing the chance of having multiples births.
Couples that are interested in PGT undergo IVF which is done in a laboratory. After egg retrieval and fertilization, a small sample of cells is
removed from each embryo five to seven days after egg retrieval. The embryos are then frozen and the samples are sent to a genetics lab for
testing. Few weeks later, the fertility centre receives the results and your physician will transfer one of the chromosomally normal embryo to your uterus.
Groups who can benefit from PGT include women with a history of very poor sperm parameters, those that have experienced recurrent miscarriages or so many failed IVF cycles, or women who have reached advanced maternal age.
When you experience several miscarriages or failed IVF cycles, it makes sense to consider PGT to determine if chromosomal issues are the reason. Fertility specialists generally recommend screening for you if you are a woman of advanced maternal age because your eggs are more likely to contain chromosomal abnormalities as you age.
If you are worried that any of your future children could potentially inherit a genetic disorder, you can actually prevent transmission and inheritance of any such common and uncommon hereditary abnormalities simply by getting screened.
This is made possible through PGT, which can make the chances of transmitting genetic disorders to be completely eliminated before they are born.
PGT aims to prevent genetically-linked maladies from being passed on to the child. The PGT screenings are to make sure that the embryos are normal and have the ability to become babies.