What is a preimplantation genetic diagnosis, and what can it detect?

In this article below, revered fertility specialist, Dr Muhammad Fatum, describes what a preimplantation genetic diagnosis is, how it is carried out, and what it can detect. 

How is a preimplantation genetic diagnosis carried out?

Preimplantation genetic diagnosis (PGD) or preimplantation genetic testing is a technology used to detect genetic or chromosomal abnormalities in embryos before they are transferred to the uterus during in vitro fertilisation (IVF). 

Firstly, the woman undergoes ovarian stimulation to recruit multiple follicular growth and development. Then, follicles are aspirated under the sonographic monitoring to collect the eggs.

Following this, the retrieved eggs are fertilised with sperm in the laboratory, creating embryos. Then, the embryos are allowed to grow in the laboratory for a few days until they reach a specific stage of development (typically around five to six days).
A few cells are carefully removed from each embryo without harming its potential for future development.

The extracted cells undergo genetic testing to identify specific genetic conditions or chromosomal abnormalities. Based on the genetic analysis results, embryos without detected genetic abnormalities are selected for transfer into the woman's uterus.

The selected embryos are then transferred into the woman's uterus, where they have the potential to implant and develop into a pregnancy with a healthy baby.

PGD, therefore, enables the identification and selection of embryos that are free from specific genetic disorders, which increases the chances of a healthy pregnancy, whilst reducing the risk of passing on inherited conditions to the offspring.

What can preimplantation genetic diagnosis detect?

Preimplantation genetic diagnosis (PGD) can detect a variety of genetic conditions and abnormalities in embryos, including: 

• Single-gene disorders
• Chromosomal abnormalities
• Sex-linked disorders
• HLA matching
• Rare genetic disorders

Are there any risks of preimplantation genetic diagnosis?

While preimplantation genetic diagnosis (PGD) is generally considered safe, there are some potential risks and limitations associated with the technology. These risks might include:

• Invasive procedure
• False negatives or false positives 
• Negative emotional impact 

Does PGD affect the embryo? 

Preimplantation genetic diagnosis (PGD) involves the removal of a few cells from the embryo for genetic testing. Thus, this biopsy procedure does carry a small risk of affecting the embryo. 

Does PGD reduce the risk of miscarriage?

Certain genetic abnormalities or chromosomal disorders in embryos can increase the risk of miscarriage. By identifying and selecting embryos without these abnormalities through PGD, the risk of miscarriage due to those specific conditions can be reduced.

However, it's important to note that miscarriage can occur due to various different factors unrelated to genetic abnormalities, such as implantation issues, hormonal imbalances, uterine abnormalities, and maternal health factors. PGD does not address these non-genetic causes of miscarriage.

To book a consultation with Dr Muhammad Fatum, you can head over to his Top Doctors profile today to do just that.