Preimplantation Genetic Testing 

Preimplantation Genetic Testing: Hope for a Healthier Future for Every Family

In an In Vitro Fertilisation (IVF) treatment, Preimplantation Genetic Testing (PGT) helps us select the best embryo to achieve pregnancy and the birth of a healthy baby.

What is PGT? 

Preimplantation Genetic Testing (PGT) is an early diagnostic method used in Assisted Reproduction to study the genetic makeup of embryos before they are transferred to the uterus. PGT helps identify and select healthy embryos, reducing the risk of implantation failure, miscarriage, and genetic abnormalities. This test may be recommended in cases with a known family history of genetic conditions or when mutations have occurred due to environmental factors or parental age. 
The process involves taking a small sample from the embryo, typically on the fifth day after fertilisation. An embryologist carefully extracts several cells without affecting the embryo's ability to develop normally. By examining these cells, we can detect genetic abnormalities early, helping prevent the transfer of affected embryos. 

PGT-A/SR (Preimplantation Genetic Testing for Aneuploidy)

PGT-A is a test that screens embryos for the correct number and structure of chromosomes. Chromosomal abnormalities can lead to implantation failure, miscarriage, or health issues for the baby. Using advanced techniques like massive DNA sequencing, we can accurately identify embryos with the proper chromosomal makeup, significantly improving the chances of a successful pregnancy.

PGT-M (Preimplantation Genetic Testing for Monogenic Disorders)

PGT-M is focused on detecting specific inherited genetic mutations that cause single-gene disorders. This test is especially important for couples who are carriers of conditions such as Duchenne muscular dystrophy, Huntington's disease, or cystic fibrosis. Through methods like polymerase chain reaction (PCR), we can analyse the embryo’s DNA to detect these mutations, reducing the risk of passing these inherited conditions on to future children.

The Difference Between PGT-A/SR and PGT-M

PGT-A and PGT-M serve different purposes in preimplantation genetic testing. PGTA examines the embryo's chromosomes to identify any numerical or structural abnormalities, while PGT-M focuses on detecting specific gene mutations responsible for single-gene diseases. Together, these tests provide a comprehensive view of the embryo's genetic health.

Requirements and Limitations of PGT 

PGT is not a replacement for prenatal diagnosis, but it is rather an option to reduce the likelihood of starting a pregnancy with a foetus carrying genetic anomalies. 

  • Some embryos may not survive the biopsy process and may stop developing. 
  • Due to the rate of mosaicism (when an embryo has a mix of normal and abnormal cells), prenatal diagnosis during pregnancy is recommended for additional confirmation. 
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When is Preimplantation Genetic Testing (PGT) Recommended? 

Preimplantation Genetic Testing is recommended for several scenarios, particularly for couples where one or both partners are carriers of genetic conditions. PGT is indicated in cases such as: 

  • Identification of Sex in Monogenic Disorders: For sex-linked monogenic disorders, such as Duchenne muscular dystrophy, Fragile X syndrome, or hydrocephalus, where knowing the sex of the embryo helps prevent the transmission of the condition. 
  • Dominant Monogenic Disorders: Conditions like Huntington's disease, myotonic dystrophy, or Marfan syndrome. 
  • Recessive Monogenic Disorders: Such as cystic fibrosis, Tay-Sachs disease, Beta-Thalassemia, or Fanconi anaemia. 
  • Chromosomal Structural Abnormalities: For carriers of structural chromosomal anomalies like translocations or inversions. 
  • Numerical Chromosomal Anomalies: In cases with numerical anomalies, such as Klinefelter syndrome mosaics. 

The Process of Preimplantation Genetic Testing 

Preimplantation Genetic Testing combines the latest advancements in embryology and genetics. It allows us to identify genetic abnormalities in the early stages of embryo development, improving IVF success rates and offering couples the best chance of having a healthy child. 

Embryo Biopsy

After IVF, several cells are gently removed from the embryo, typically on the fifth day of development. This biopsy is performed with an inverted microscope and micromanipulation system, ensuring the embryo remains unharmed and maintains its ability to develop normally. 

Genetic Studies:

  • Aneuploidy and Structural Alterations Study: If chromosomal abnormalities are suspected, massive DNA sequencing provides a complete analysis of all chromosomes to detect even minimal alterations. 

  • Monogenic Disease Study: For detecting specific gene mutations, techniques like PCR are used to amplify and analyse the DNA to identify genetic mutations. 

Transfer of Healthy Embryos

Once healthy embryos are identified through genetic analysis, they are transferred into the uterus, as in a conventional IVF procedure. 

PGT Costs 

Understanding the costs associated with Preimplantation Genetic Testing (PGT) is important when planning Assisted Reproduction treatment. Costs may vary depending on the type of test (PGT-A or PGT-M) and the number of embryos tested. At FIV Valencia, our team will provide a detailed breakdown of costs, so you can evaluate and choose your

treatment plan. For detailed pricing information, please refer to our price list.

Price List book a consultation

Preimplantation Genetic Testing 
FAQs

Who should consider PGT?

PGT is recommended for couples with a family history of genetic disorders, carriers of chromosomal abnormalities, those who have experienced recurrent miscarriages, or individuals of advanced maternal age. It is also useful for those undergoing IVF who want to ensure the healthiest possible embryos are selected. 

How is PGT performed?

During the IVF process, several cells are gently removed from each embryo, typically on the fifth day of development. These cells are analysed to identify any genetic abnormalities, and the healthiest embryos are then selected for transfer to the uterus. 

Does PGT affect the embryo's development?

The biopsy procedure used in PGT is designed to be safe and does not affect the embryo's ability to develop into a healthy baby. 

Is PGT a replacement for prenatal testing?

PGT is not a replacement for prenatal testing but rather a way to reduce the risk of starting a pregnancy with a genetic anomaly. Prenatal testing later in pregnancy is still recommended, especially due to the possibility of mosaicism (where an embryo has a mix of normal and abnormal cells). 

What are the limitations of PGT?

Although PGT helps reduce the likelihood of genetic abnormalities, it does not eliminate all genetic risks. Additionally, some embryos may not survive the biopsy process. 

How long does it take to get PGT results?

The timeframe for PGT results can vary, but it typically takes about 1 to 2 weeks after the biopsy for the genetic analysis to be completed. Your healthcare team will discuss the findings with you once they are available. 

How does PGT improve the chances of a successful pregnancy?

By selecting embryos with the correct number of chromosomes or those free of specific genetic mutations, PGT increases the likelihood of a successful pregnancy and the birth of a healthy baby. This testing helps reduce the risk of implantation failure, miscarriage, and genetic disorders.