1. Concept traceability: The evolution from "PGD/PGS" to "PGT"
Before2017, the third-generation IVF technology was mainly divided into two categories: PGD (pre-implantation genetic diagnosis) and PGS (pre-implantation genetic screening).
PGD: For couples who have been identified as carrying single-gene genetic disorders or chromosomal abnormalities (such as balanced translocations), this technique involves detecting and eliminating embryos that are responsible for these diseases.
PGS: Designed for older individuals with no known genetic disorders, those who experience recurrent miscarriages or transplant failures. It involves screening embryos for abnormalities in chromosome number (such as Down syndrome).
PGT-A (aneuploidy screening) replaces the old name PGS to detect chromosomal numberabnormalities
PGT-M (Monogenic Disease Test) corresponds to screening for monogenic diseases in the originalPGD
PGT-SR (Structural Abnormality Detection) targets structural problems such as chromosome translocations and inversion.
PGT-SR (Structural Anomaly Detection)Regarding structural issues such as chromosomal translocations and inversions, etc.

2. Core differences: technical goals and applicable groups
1. Different detection targets
PGT-M (formerly PGD)focuses on single gene diseases, such as thalassemia, spinal muscular atrophy (SMA), etc., and uses gene sequencing to lock pathogenic mutation sites and block the genetic chain.
PGT-A(PGS)The screening aims to determine whether there are any abnormalities in the number of chromosomes in embryos (for example, having an extra copy of chromosome 21 can lead to Down syndrome). This test does not target specific genes.
2. Significant differences in applicable population
PGT-M (formerly PGD)
·Applicable population: Family history of genetic diseases, known genetic mutation carriers
·Detection focus: Monogenic diseases (such as cystic fibrosis, hemophilia)
·Technical means: PCR, gene sequencing (NGS)
·Clinical significance: Avoid the birth of children with specific genetic diseases.
·Applicable population: elderly (≥35 years old), repeated abortion, multiple transplantfailures
·Detection focus: Chromosomal aneuploidy (such as trisomy 21, trisomy 18)
·Technical means: High-throughput sequencing (NGS), microarray comparative genomic hybridization (aCGH)
Reduce the risk of abortion.
Reduce the risk of miscarriage.

3. Technology upgrades: Why is PGT more respected?
PGT-A can detect all 23 pairs of chromosomes through whole-genome sequencing, while traditional PGS only screens 5-10 pairs, resulting in a higher risk of missing detection.
PGT-A can detect all 23 pairs of chromosomes through whole-genome sequencing. In contrast, traditional PGS only screens 5-10 pairs of chromosomes, resulting in a higher risk of missed detections.
In modern clinical practice, PGT-M and PGT-A are often used together.
,PGT-MPGT-A.For example, in couples with balanced chromosome translocation (PGT-SR), simultaneous screening for aneuploidy (PGT-A) can further increase the rate of healthy embryos.
PGT technology only screens embryos and does not modify genes, avoiding ethical disputes over gene editing and is more in line with medical ethics.
PGT technology only selects embryos, without altering their genes. This approach avoids the ethical controversies associated with gene editing and aligns more closely with medical ethics standards.

4. How to choose? Doctor advised
Clarifythe genetic risk: If the family has a history of monogenic disease or chromosomal structural abnormalities, PGT-M is preferred
Advancedage or repeated failure: PGT-A is recommended to reduce the probability of abortion due to chromosomal abnormalities
Comprehensive screening: Some institutions provide a combination of PGT-A+PGT-M solutions to achieve dual protection.

5. Future Outlook
With the iteration of sequencing technologies (such as long-read-long sequencing, AI-assisted analysis), the detection accuracy and efficiency of PGT will continue to improve. At the same time, international research is exploring the application of PGT in areas such as tumor susceptibility gene elimination and HLA matching to provide personalized fertility plans for more families.