Embryo aneuploidy (abnormality) & IVF: to test or not, and when to test it?

Antonio Urbano Carrillo, PhD
Geneticist at UR Vistahermosa , UR Vistahermosa
From this video you will find out:
  • What is aneuploidy, how common is it, and how can we detect it?
  • What is PGT-A, and when is it most often indicated?
  • What percentage of PGT-tested embryos are normal?
  • What is niPGT-A, and how does it work?

Embryo aneuploidy (abnormality) & IVF: to test or not, and when to test it?

During this webinar session, Dr Antonio Urbano Carrillo, Clinical Geneticist from UR Vistahermosa International Group, discussed a crucial topic of embryo aneuploidy and its implications for IVF treatments.

Understanding Chromosome Structure and Karyotyping

Chromosomes are fundamental units of genetic information in humans. Karyotyping reveals their distribution in 23 pairs. Pairs 1 to 22 are autosomes, common to both sexes. The 23rd pair consists of sex chromosomes, differentiating males (XY) from females (XX). This male karyotype showcases the normal 46 chromosomes, divided into 23 pairs. Conversely, individuals can possess variations such as trisomies, which result in chromosomal disorders like Down syndrome.

Karyotyping provides a visual insight into the genetic makeup of an individual.

The typical chromosomal makeup is 46, with 23 pairs, but exceptions arise due to errors in cell division. Trisomy, indicated by 3 chromosomes in a pair, can lead to conditions like Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), or Patau syndrome (Trisomy 13). Monosomy, with a chromosome missing, also exists. These deviations can impact viability and pregnancy outcomes, often leading to miscarriages or implantation failure.

The Influence of Maternal Age and Genetic Screening

Maternal age plays a crucial role in chromosomal abnormalities. Advanced maternal age increases the likelihood of aneuploidy, where embryos have an abnormal number of chromosomes. This phenomenon intensifies the risks of miscarriage and chromosomal syndromes. Graphical depictions underscore how fertility decreases and miscarriage rates rise with age. However, genetic screening like preimplantation genetic testing (PGT) can aid in embryo selection, improving IVF success rates.

The Power of PGT-A and its Applications

PGT-A enables the selection of viable embryos for transfer, enhancing the chances of successful pregnancies. Trisomies and monosomies can be detected, allowing the prioritization of healthier embryos for implantation. PGT’A’s benefits extend to couples with recurrent miscarriages, advanced maternal age, or male infertility due to azoospermia. Moreover, PGT-A (aneuploidy screening) and PGT-M (monogenic disorder screening) have revolutionized assisted reproductive technology.

PGT offers couples a powerful tool to optimize their chances of conceiving a healthy baby.

Non-Invasive Alternatives and Future Prospects

Non-invasive screening techniques like NiPGT-A look promising. Similar to non-invasive prenatal tests (NIPT), this approach minimizes risks associated with embryo biopsies. Concordance rates between these methods and traditional PGT demonstrate the effectiveness of these innovations. Such techniques hold potential for further refining embryo selection and reducing the time to successful pregnancies.

In conclusion, understanding chromosomal structure, variations, and screening techniques like PGT can greatly influence pregnancy outcomes. As science progresses, these tools offer new ways to ensure healthy pregnancies and births.

- Questions and Answers

How can I ensure that the embryo testing is performed at a reputable and reliable laboratory?

Embryo testing is typically performed at reputable and reliable laboratories. The field is comprised of a small number of trustworthy facilities. If a laboratory lacks credibility, it could hinder a career in this field. Practitioners continually enhance their skills and maintain a strong reputation.

What are the chances of false positive or false negative results in PGT-A?

False positive and false negative outcomes exist in PGT-A, but the rates are generally low. While no test is perfect, the likelihood of both false positive and false negative results is minimized in PGT-A. Positive predictive value and negative predictive value are crucial metrics here, and the false positive rate is slightly higher than the false negative rate.

Can embryo testing harm the embryo?

Experimental biopsies pose a minimal risk to embryo quality. The quality of the embryo is a vital consideration. Poor-quality embryos are more likely to be affected. The impact of the biopsy on the embryo is negligible, and the risk is minor.

I’m 34, diagnosed with PCOS, and have been trying for 6 years. Should I consider egg donation due to unsuccessful transfers?

Considering your history and diagnosis, if the PGT-A results indicate that all your embryos are unviable, it might be time to think about egg donation. If you have 1 viable embryo, transferring it is a good option. An egg donor could be considered if needed.

I have 1 blastocyst, and I’m considering genetic testing. My doctor disagrees due to the donor’s age. What’s your opinion?

Despite your donor’s age, testing your last embryo might be beneficial. This is especially true if you’ve had implantation failures before. The testing provides valuable information for decision-making.

Can transferring an aneuploid embryo increase the risk of ectopic pregnancy?

Transferring an aneuploid embryo doesn’t directly increase the risk of an ectopic pregnancy. The specific type of embryo that relates to ectopic pregnancies is different from aneuploid embryos. It’s a good idea to discuss any concerns with your doctor.
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Picture of Antonio Urbano Carrillo, PhD

Antonio Urbano Carrillo, PhD

Dr Antonio Urbano Carrillo is a Clinical Geneticist. Doctor in Biology from Miguel Hernández University (UMH). Master in Biotechnology from Pablo de Olavide University (Seville) and Master in Genetics and Reproductive Medicine from Miguel Hernández University (Alicante). Responsible for the area of ​​molecular and preimplantation genetic diagnosis of the Genetics Unit of the UR International Group (Hospital Vistahermosa in Alicante). Associate professor at the Miguel Hernández University, and I teach in Master's Degree in Genetics and Reproductive Medicine at the UMH, Expert Course in Genomics at EADE Málaga, Update Course in Human Genetics 3 edition (AEGH), Applications of Genetics in Human Reproduction Assisted (Grupo de interés de Genética de ASEBIR). Member of the Commission for Reproductive Genetics of AEGH, and member of ASEBIR.
Event Moderator
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Caroline Kulczycka

Caroline Kulczycka is managing MyIVFAnswers.com and has been hosting IVFWEBINARS dedicated to patients struggling with infertility since 2020. She's highly motivated and believes that educating patients so that they can make informed decisions is essential in their IVF journey. In the past, she has been working as an International Patient Coordinator, where she was helping and directing patients on their right path. She also worked in the tourism industry, and dealt with international customers on a daily basis, including working abroad. In her free time, you’ll find her travelling, biking, learning new things, or spending time outdoors.
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