Genetics have comprised a large portion of scientific research over the last century, from the discovery of the double helix in 1953, to genome sequencing in the early 1990s. In particular, this research has been invaluable to the field of infertility and assisted reproduction. Now, thirty-four years after the first “test tube baby” was born, scientists are able to examine an embryo for a range of genetic disorders before implantation, potentially saving lives and revolutionising medical practice.
What is IVF?
IVF stands for ‘in vitro fertilisation’, which is a very delicate process used to help infertile couples become pregnant. Basically, the egg and sperm of a couple are fertilised in a fluid medium under lab conditions. Then the fertilised egg, now called a zygote, is implanted in the woman’s uterus with the hopes that a normal pregnancy develops.
IVF is now a very common technology, and has helped thousands of infertile couples become pregnant. (IVFAustralia 2011)
However, one of the most common causes of a failed pregnancy is aneuploidy, which occurs when the fertilised blastocyst has an incorrect number of chromosomes.
What is a genetic abnormality?
A standard karyotype has 22 pairs of chromosomes, as well as a 23rd pair that determines the sex, and any variation in these 46 chromosomes can cause major damage to a human being.
The most important type of disorder is a trisomy, which is when three copies of a chromosome appear in a karyotype rather than a standard pair. A well-known example of this is Down Syndrome, which is trisomy 21 and has three copies of the 21st chromosome.
Others include Patau Syndrome and Edwards Syndrome, all of which have severe effects on physical appearance and social and mental development. (March of Dimes 2009) Check out this link to read more:
Until recently, there has been no way for doctors to prevent chromosome-linked disorders. However, in the last few years, technology has progressed in leaps and bounds, and now we have the ability to test embryos before they are implanted. This improves the chances of an infertile couple falling pregnant and also significantly reduces the chance of a child being born with a serious genetic condition.
Is PGD the answer?
Pre-implantation genetic diagnosis, or PGD, is the process of screening an embryo before inserting it into the uterus, to make sure it has a full set of chromosomes. The newest PGD technology is called ‘24sure Advanced Embryo Screening’ and was released just last year. (BlueGnome 2011)
24sure is able to screen all 23 pairs of chromosomes by examining a biopsy of the embryo. The resulting karyotype gives information as to whether the cell has a normal number of cells, known as “euploid”. (BlueGnome 2010)
From this information, the doctor can choose an embryo with the correct number of chromosomes, which significantly improves the chance of a successful pregnancy! Also, couples can have the added security of knowing that their child will not have a severe chromosomal abnormality.
This is particularly important for parents with a heritable condition that they don’t want to pass on to their children, such as Muscular Dystrophy.
As you can see, IVF and genetic screening are at the forefront of medical research, and technology is continuously progressing. In the years to come, this will have far-reaching implications for science, medicine and the treatment and prevention of human disease.