In 1990, doctor Handyside and others used the technology of identifying the existence of the Y chromosome to successfully reduce adrenaleucaryotic deficiency and neurodevelopment retardation associated with X-linked recessive genetic diseases

This

is the first report of a successful clinical application of preimplantation genetic testing (PGT). With the continuous development of medical genetics and gene detection technology, PGT is in the auxiliary

The field of reproduction is increasingly widely used. PGT as a technical means of assisted reproduction, is also an early form of prenatal diagnosis, can avoid the existence of serious monogenic genetic diseases or congenital

Transplantation of abnormal and unhealthy embryos effectively reduces the damage caused to pregnant women by pregnancy termination surgery due to spontaneous abortion or medical reasons, and is of great significance to protecting the health of women and newborns.

In the early days, PGT was divided into two parts: preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS). PGD is suitable for patients with monogenic diseases and chromosomal diseases;PGS is suitable for women

Patients with advanced age, repeated miscarriages, repeated implant failures, and severe male factor infertility.

In 2017, the International Committee on the Monitoring of Assisted Reproductive Technology conducted a new classification of PGT, including three parts: PGT-A, PGT-SR, and PGT-M. PGT-A is used for elderly women with repeated miscarriages

Patients with repeated implant failures and severe male factor infertility can be screened for aneuploid embryos. Embryo aneuploidy is one of the most common causes of early abortion. PGT-SR is suitable for translocation

Patients with chromosomal structural abnormalities such as inversion, duplication, and deletion can detect copy number variations in the embryo. By transplanting euploid embryos that do not carry deletions and duplications, we can reduce the risk of chromosomal imbalance

The probability of repeated transplant failure and early abortion.

PGT-M can screen out embryos with normal genotypes, avoiding the physical and mental trauma caused to the mother caused by terminating pregnancy due to a pathogenic mutation discovered during the prenatal examination. In PGT-M, the application is based on second-generation sequencing (Nex

generation sequencing (NGS) can not only distinguish the chromosome where the pathogenic gene is located from its homologous chromosome, but also avoid allele tripping from direct detection

(Allele dropout, ADO) or misdiagnosis caused by recombination has important clinical significance for PGT-M in autosomal dominant diseases. One-generation sequencing of the mutation sites was then combined based on N

GS single nucleotide polymorphism (SNP) haplotype analysis technology can improve the accuracy of embryonic testing results and significantly reduce the misdiagnosis rate. and

In the SNP haplotype analysis of PGT-M, genetic information from probands, traceable family samples, gametes or embryos from patients with untraceable families, or patients with new mutations can be used for linkage

Analysis.