Preimplantation genetic testing

Preimplantation genetic diagnosis (PGD) is a way of checking embryo cells before they are placed, or implanted, inside a mother's body. It is also named preimplantation genetic testing (PGT).[1] The good thing about PGD is that it can let the parents not choose the embryo which will develop into a child with a certain disease. This way, the parents do not have to choose to stop the pregnancy if the baby has the disease. To do preimplantation testing, doctors take the mother's eggs from her body. Then, the embryo is tested, and put back in the mother after 5 or 6 days of growing.[2]

Polygenic preimplantation genetic testing works on polygenic (multi-gene) diseases (shown above). Monogenic preimplantation genetic testing works on single-gene diseases.

The first preimplantation testing was done by choosing a female embryo, because the disease was only possible if there was one X chromosome, such as in male embryos.[3][4]

It can also test to see if the embryo has a different number of chromosomes than normal. This is called preimplantation genetic testing for aneuploidy, or PGT-A.[5] The other types of preimplantation genetic testing are for gene (monogenic) disorders (PGT-M), for many gene (polygenic) disorders (PGT-P), for seeing if large parts of the chromosomes are improperly put together (PGT-SR).[6][7]

Sometimes, tests can also be done on the mother's eggs or the father's sperm before they meet to make a baby. These can also be part of PGD.[8]

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Notes and references

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  1. "PGD / PGS - A boon for couples with genetic issues - Times of India". The Times of India.
  2. Sullivan-Pyke C, Dokras A (March 2018). "Preimplantation Genetic Screening and Preimplantation Genetic Diagnosis". Obstetrics and Gynecology Clinics of North America. 45 (1): 113–125. doi:10.1016/j.ogc.2017.10.009. PMID 29428279.
  3. Joyce C. Harper (2009-05-28). "Introduction to preimplantation genetic diagnosis" (PDF). In Joyce C. Harper (ed.). Preimplantation Genetic Diagnosis: Second Edition. Cambridge University Press. ISBN 9780521884716.
  4. Handyside AH, Kontogianni EH, Hardy K, Winston RM (April 1990). "Pregnancies from biopsied human preimplantation embryos sexed by Y-specific DNA amplification". Nature. 344 (6268): 768–70. Bibcode:1990Natur.344..768H. doi:10.1038/344768a0. PMID 2330030. S2CID 4326607.
  5. "PGDIS POSITION STATEMENT ON CHROMOSOME MOSAICISM AND PREIMPLANTATION ANEUPLOIDY TESTING AT THE BLASTOCYST STAGE". Preimplantation Genetic Diagnosis International Society. July 19, 2016.
  6. Kimelman, Dana; Pavone, Mary Ellen (2021-01-01). "Non-invasive prenatal testing in the context of IVF and PGT-A". Best Practice & Research Clinical Obstetrics & Gynaecology. Reproduction at an Advanced Maternal Age. 70: 51–62. doi:10.1016/j.bpobgyn.2020.07.004. ISSN 1521-6934. PMID 32739290. S2CID 220944472.
  7. Treff, Nathan R.; Zimmerman, Raymond; Bechor, Elan; Hsu, Jeff; Rana, Bhavini; Jensen, Jens; Li, Jeremy; Samoilenko, Artem; Mowrey, William; Van Alstine, James; Leondires, Mark (2019-08-01). "Validation of concurrent preimplantation genetic testing for polygenic and monogenic disorders, structural rearrangements, and whole and segmental chromosome aneuploidy with a single universal platform". European Journal of Medical Genetics. 62 (8): 103647. doi:10.1016/j.ejmg.2019.04.004. ISSN 1769-7212. PMID 31026593. S2CID 135463733.
  8. Page 205 in: Zoloth, Laurie; Holland, Suzanne; Lebacqz, Karen (2001). The human embryonic stem cell debate: science, ethics, and public policy. Cambridge, Mass: MIT Press. ISBN 978-0-262-58208-7.