Types of Pre-Implantation Genetic Testing
PGT-A (Aneuploidy Screening)
- Description: Screens embryos for aneuploidy, which refers to abnormal chromosome numbers (e.g., trisomy, monosomy).
- Benefits: Helps identify embryos with the correct number of chromosomes, reducing the risk of miscarriage and increasing the chance of successful implantation and pregnancy.
PGT-M (Monogenic Disorder Screening)
- Description: Identifies embryos affected by specific monogenic disorders, which are caused by mutations in a single gene (e.g., cystic fibrosis, sickle cell anemia).
- Benefits: Allows couples who are carriers of genetic disorders to select unaffected embryos for transfer, reducing the risk of passing on the genetic disease to their offspring.
PGT-SR (Structural Rearrangement Screening)
- Description: Used for couples with structural chromosomal rearrangements, such as translocations or inversions, which can lead to infertility, recurrent miscarriages, or chromosomal abnormalities in offspring.
- Benefits: Identifies embryos with balanced chromosomal rearrangements for transfer, reducing the risk of unbalanced embryos and associated complications.
PGT for Polygenic Disorders
- Description: Emerging technologies are being developed for the identification of polygenic disorders, which are influenced by multiple genetic factors.
- Benefits: Aims to assess the genetic predisposition of embryos to complex conditions such as heart disease, diabetes, or certain cancers.
Procedure
- Timing: PGT is performed during the IVF process, typically after embryos reach the blastocyst stage (around day 5 or 6 after fertilization).
- Biopsy: Involves the biopsy of one or more cells from each embryo, usually performed using a specialized micromanipulation technique.
- Genetic Analysis: The biopsied cells are sent to a genetic laboratory for analysis, where they undergo genetic testing using techniques such as polymerase chain reaction (PCR), fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH), or next-generation sequencing (NGS).
- Selection: After genetic analysis, embryos free from the targeted genetic disorder or chromosomal abnormality are identified for transfer into the uterus.
Benefits
- Increased Pregnancy Rates: PGT can improve the selection of chromosomally normal embryos, leading to higher implantation rates and reduced miscarriage rates.
- Reduced Risk of Genetic Disorders: Allows for the detection and avoidance of embryos affected by specific genetic diseases, reducing the likelihood of passing on genetic disorders to offspring.
- Family Planning: Provides valuable information for family planning decisions, particularly for couples at risk of transmitting genetic diseases or chromosomal abnormalities to their children.
Considerations
- Cost: PGT is an additional expense on top of the cost of IVF treatment and may not be covered by insurance.
- Accuracy: PGT is not 100% accurate, and false-positive or false-negative results may occur.
- Ethical Considerations: Raises ethical questions related to the selection of embryos based on genetic characteristics, as well as concerns about embryo disposal and the potential for creating "designer babies." Sex chromosomes cannot be revealed by genetic laboratories in India due to legal and ethical considerations.
- Emotional Impact: Can be emotionally challenging for individuals and couples, particularly if embryos are identified as affected by genetic disorders or if no viable embryos are available for transfer.
Regulations and Guidelines
- Regulation: PGT is regulated and governed by various professional organizations and regulatory bodies, which provide guidelines and recommendations for its use in clinical practice.
- Guidelines: Address issues such as patient eligibility criteria, informed consent, genetic counseling, laboratory protocols, and the reporting of results.
Conclusion
Pre-Implantation Genetic Testing offers a valuable tool for individuals and couples seeking to build a family while minimizing the risk of genetic diseases and chromosomal abnormalities in their offspring. However, it's essential for individuals considering PGT to carefully weigh the potential benefits, risks, and ethical considerations in consultation with their healthcare providers and genetic counselors.
At Bliss IVF, our experienced team is dedicated to providing comprehensive and personalized care to help you make informed decisions about your reproductive options. We are committed to supporting you through every step of your fertility journey with expertise and compassion.
