Pre-Implantation Genetic Diagnosis (PGD)

What is PGD?

PGD – Preimplantation Genetic Diagnosis is a test to detect chromosomal abnormalities in the embryo. This laboratory procedure is performed in conjunction with IVF (In-vitro fertilization), in which the eggs and sperm are united in an outside environment to increase the chances of pregnancy in an infertile couple. PGD is required when either partner carries a genetic abnormality, which could be passed on to their child. If you are diagnosed with a genetic disorder, IVF with PGD can mitigate the risk of the child inheriting your genetic disorder.

Did you know 2% to 5% of children are born with genetic disorders? These chromosomal abnormalities account for 50% of the total death rate of newborns. To mitigate the risk of the child developing a genetic disorder, parents with a family history of genetic diseases can consider PGD.

PGD Process

IVF involves the extraction of healthy and mature eggs from women’s ovaries and uniting them with sperm to form embryos. However, if the parents have any genetic disease, these embryos can be sent to the lab for PGD screening. This ensures that only healthy embryos that do not carry any chromosomal abnormality are implanted into the woman’s uterus.

Let’s understand the breakdown of the PGD process:

1. Egg Retrieval:

PGD is a part of the IVF process, in which the woman’s eggs are retrieved through a minimally invasive procedure. Before that, the woman receives hormonal shots that stimulate the production of multiple eggs.

2. Fertilization:

The healthy and mature eggs are fertilized with sperm in a closely monitored environment. Once fertilized, these eggs turn into embryos. The embryo is stored in the lab for 5-6 days until blastocysts develop.

3. Biopsy:

The scientist carefully extracts one or two cells from the blastocyst without destroying the cell mass. These cells are sent into the lab for genetic screening.

4. Genetic Testing:

These embryo cells are tested for genetic abnormalities using FISH, PCR, and NGS (Next-gen screening). These PGD techniques can detect single-gene disorders, specific diseases, and any type of chromosomal abnormality in the embryo.

5. Analysis:

Your healthcare provider will analyze the biopsy results and select healthy embryos free from chromosomal defects.

6. Embryo Transfer:

The selected embryos are then transferred into the woman’s uterus through a minimally invasive procedure. The procedure involves inserting a catheter through the cervix into the woman’s uterine lining. It is performed using an ultrasound. Depending on the genetic screening results and your health, one or more embryos can be implanted into your uterus.

7. Pregnancy Testing:

You can take a test two weeks after embryo implantation. If your test results are positive, your pregnancy will be monitored to ensure proper fetal development.

8. Frozen Embryos:

IVF can be performed using fresh and frozen embryos. A couple can decide to freeze a few embryos (if not all of them were implanted into the uterus) for future attempts. In case the IVF cycle fails, they can use these frozen embryos to try again.

The two popular techniques used in the PGD process are:

PCR—Polymerase Chain Reaction

PCR—polymerase chain reaction is an effective technique for conducting preimplantation genetic diagnosis. In this process, a single cell is extracted from the fertilized embryo. The DNA sample is collected from this cell and amplified to make screening easier. The procedure is commonly used in cases of single-gene disorder or monogenic disease.

FISH—Fluorescent In Situ Hybridization

FISH is used to detect chromosomal abnormalities in the embryo, like Down syndrome. The healthcare specialist examines the embryo cells using a special microscope to determine whether they carry the required number of chromosomes. FISH—Fluorescent In Situ Hybridization helps identify the embryo’s chromosomal structure so your doctor can pick the most viable one.

PGD Technique for Family Balancing

Not every couple that chooses PGD screening is infertile. Some can conceive naturally but might experience fetal death at an early stage. Others might fear their child carrying the genetic disorder that runs in their family.

In some cases, the PGD technique is used for family balancing. If a couple wants a child of a certain gender, they can undergo Preimplantation Genetic Diagnosis to separate the male and female embryos. Their selected gender embryo is then implanted into the woman’s uterus.

Who Needs PGD Treatment?

PGD comes with IVF and is a highly recommended procedure for couples at an increased risk of passing genetic diseases to their offspring. As mentioned above, PGD treatment also helps you identify the gender of the child. Here’s when you should consider PGD:

You have a family history of a genetic disorder
You have certain genetic mutations that can be passed onto your child
Multiple pregnancy losses
A woman who can’t conceive naturally because of their age
To identify sex-related genetic disorders
For family balancing

PGD may or may not be conducted during an IVF cycle. It depends on your risk of passing genetic diseases to the child.

PGD Success Rates

PGD success rates vary depending on the reason you are considering it. A study shows that the chances of miscarriage drop significantly in women (especially above 35) who undergo PGD testing during their IVF cycle. The test showed a whopping 95% chance of a woman giving live birth after PGD testing.

Benefits and Risks of PGD

PGD can help prevent genetic disorders in your offspring, but like any medical procedure, it comes with its share of risks. Let’s check out the benefits and risks of PGD.

Benefits

Risk

Cost of PGD Treatment

PGD pregnancy involves testing the embryo cells for genetic mutation and any chromosomal abnormality. The procedure is a bit complex. The cost of PGD procedure depends on the clinical or medical history of the patient.

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