Preimplantation Genetic Screening (PGS) is a technique used to identify genetic defects in embryos created through in vitro fertilization (IVF) before pregnancy.
Women who have a history of recurrent pregnancy losses or repeated implantation failures will benefit from PGS because it avoids the transfer of aneuploid embryos which will results in miscarriages and IVF failures.
Presently, the rate of birth defect is as high as 5.6%. The infertility rate of women of child-bearing age is about 10~15%, and about 15~20% natural pregnancies suffer from spontaneous abortion (SA) and about 2~8% couples suffer from recurrent spontaneous abortion (RSA). Most of these problems are caused by chromosomal abnormalities.
The first generation of PGD/PGS technology
PCR and FISH
The second generation of PGD/PGS technology
aCGH and SNP array
The third generation of PGD/PGS technology
NGS
Comprehensive
Faster
Could be the largest NGS-based PGS data set
Examine all 24 chromosomes including autosomes 1-22 and the sex chromosomes (X, Y)
Chromosome aneuploidy number and structural abnormalities
Detect chromosome micro-repeat/micro-deletion of >4Mb in size
Unsurpassed accuracy, a less than 0.1% false-positive rate
Automated analysis with a patented bioinformatics analytical software
A new evaluation index for embryos
Big data based
Mosaic embryos indentification
Innovative bioinformatics algorithm
> 30% mosaics
Target patients for PGS
| Diseases | Location | Incidence | Remarks |
| Down syndrome | Trisomy 21 （47,XX; 47,XY） |
1/750-800 | An increased incidence in women of advanced age |
| Edwards syndrome | Trisomy 18 （47,XX; 47,XY） |
1/6,000 | Most of the fetus miscarry during pregnancy |
| Patau syndrome | Trisomy 13 （47,XX; 47,XY） |
1/10,000 | 95% fetus will die in the uterus |
| Trisomy X syndrome | Trisomy X （XXX） |
1/1,000（girls） | Most of the patients do not have obvious clinical manifestations, while only 10% will have a diagnosis |
| Klinefelter syndrome | 47,XXY | 1/500-1,000（boys） | Symptoms are relatively mild. Miscarry rate is as high as 50%. |
| XYY syndrome | 47,XYY | 1/1,000（boys） | Not related to advanced maternal age |
| Turner syndrome | 45,X | 1/2,500（girls） | Miscarry rate is about 15% |
| Diseases | Location | Incidence | Remarks |
| Angelman syndrome | Chr 15q11.2-q13 | 1/12,000-25,000 | Unable to live independently |
| Cri du chat syndrome | Chr 5p | 1/15,000-50,000 | More common in women |
| DiGeorge syndrome | Chr 22q11.2 | 1/4,000-5,000 | Some carrier are asymptomatic |
| Langer-Giedion syndrome | Chr 8q23.3-q24.13 | Unknown | A very rare disease |
| Miller-Dieker syndrome | Chr 17p13.3 | 1/100,000-300,000 | Most patients will die prematurely |
| Prader-Willi syndrome | Chr 15q11.2-q13 | 1/100,000-300,000 | Have a normal lifespan. No treatment is available |
| Smith-Magenis syndrome | Chr 17p11.2 | 1/25,000-50,000 | Many patients are not diagnosed |
| Williams-Beuren syndrome | Chr 7q11.23 | 1/7,500-2,000 | Have a shorter lifespan. No treatment is available |
| Wolf-Hirschhorn syndrome | Chr 4p16.3 | 1/50,000 | More common in women |