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.