The term preimplantation genetic diagnosis (PGD) refers to genetic testing that takes place before an embryo implants in the uterus. To far, three methods have been used for PGD. The initial method relied on polar body removal, with the genetic state of the oocyte inferred from the polar body test findings. The oocyte is presumed to be "normal" in the case when the polar body carries the mutant gene, and hence an embryo generated by fertilisation of this oocyte would be unaffected by the genetic condition of interest. Blastomere biopsy is a second technique of PGD in which one or two blastomeres from an eight-cell (day 3) embryo are extracted and tested for the genetic condition of interest. Only embryos found not to have the genetic variant are transferred into the uterus.
This is the approach that has been employed the most in the past. Finally, during the blastocyst stage, Preimplantation Genetic Diagnosis can be conducted by sampling a part of the trophectoderm (early placenta). When comparing children born following PGD to infants born after other assisted reproductive technologies, research demonstrate no increased risk of birth abnormalities or development issues.
Read the complete blog- https://medium.com/@poojas_37665/preimplantation-genetic-diagnosis-is-a-type-of-genetic-profiling-of-embryos-before-implantation-and-f11b0f755e2a?postPublishedType=initial
