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What is the Preimplantation Genetic Diagnosis (PGD)?
Grade Level:
Class 12
AI/ML, Physics, Biotechnology, FinTech, EVs, Space Technology, Climate Science, Blockchain, Medicine, Engineering, Law, Economics
Definition
What is it?
Preimplantation Genetic Diagnosis (PGD) is a special test done on embryos (very early babies) created through IVF (In Vitro Fertilisation) before they are placed in the mother's womb. It helps check if the embryo has serious genetic diseases or chromosome problems, like a 'quality check' before a product is shipped.
Simple Example
Quick Example
Imagine you are buying mangoes for your family. You don't just pick any mango; you check for ripeness, spots, and any damage. PGD is like checking the 'quality' of an embryo for genetic problems before it's 'planted' in the womb, ensuring it's healthy, similar to how you'd pick a good mango.
Worked Example
Step-by-Step
Let's say a couple wants to have a baby, but both carry a gene for a serious genetic disease like Thalassemia, which means their baby has a high chance of inheriting it.
---1. The couple undergoes IVF, where eggs are fertilised by sperm in a lab dish to create several embryos.
---2. When these embryos are 3-5 days old, a tiny few cells are carefully removed from each embryo. This is like taking a tiny sample from a fruit without damaging the fruit itself.
---3. These cells are then sent for genetic testing to check if they carry the Thalassemia gene.
---4. The results come back. Out of 5 embryos, 2 are found to be free of the Thalassemia gene, 2 carry the gene but won't develop the disease, and 1 has the disease.
---5. The doctor then selects the healthy embryos (the 2 free of the gene) to be transferred into the mother's womb.
---ANSWER: This process helps the couple choose an embryo that is most likely to be born without the genetic disease.
Why It Matters
PGD is a powerful tool in Medicine, especially in reproductive health, helping families avoid passing on severe genetic diseases. Doctors and genetic counsellors use this technology to guide parents, offering hope and healthier beginnings. It combines Biotechnology and advanced diagnostic methods to improve lives.
Common Mistakes
MISTAKE: Thinking PGD treats the genetic disease in the embryo. | CORRECTION: PGD does not treat the disease; it only identifies if an embryo has a genetic condition so that healthy embryos can be selected for implantation.
MISTAKE: Believing PGD guarantees a 'perfect' baby free from all health issues. | CORRECTION: PGD only screens for specific genetic conditions it's designed to test for. It doesn't check for every possible health problem, nor does it guarantee a healthy pregnancy or birth.
MISTAKE: Confusing PGD with prenatal tests done during pregnancy, like amniocentesis. | CORRECTION: PGD is done BEFORE pregnancy (on embryos in the lab), while prenatal tests like amniocentesis are done AFTER pregnancy has started (on the fetus in the womb).
Practice Questions
Try It Yourself
QUESTION: What is the main purpose of Preimplantation Genetic Diagnosis (PGD)? | ANSWER: To screen embryos for genetic diseases or chromosome abnormalities before implantation in the womb.
QUESTION: A couple knows they are both carriers for cystic fibrosis. They undergo IVF. How can PGD help them? | ANSWER: PGD can test the embryos created via IVF to identify which ones are free of the cystic fibrosis gene, allowing the doctor to select healthy embryos for transfer.
QUESTION: If PGD identifies an embryo with a genetic disorder, what happens to that embryo? Can it be 'fixed'? | ANSWER: No, the embryo cannot be 'fixed'. Embryos identified with a genetic disorder are typically not selected for implantation. The couple can choose to discard them, donate them for research, or in some cases, store them.
MCQ
Quick Quiz
Which of the following best describes when Preimplantation Genetic Diagnosis (PGD) is performed?
During the first trimester of pregnancy
On an embryo before it is implanted into the mother's womb
After the baby is born, to check for genetic diseases
On sperm and egg cells before fertilisation
The Correct Answer Is:
B
PGD is specifically performed on embryos created through IVF, before they are transferred to the uterus. It's a pre-implantation screening method.
Real World Connection
In the Real World
In India, many couples face challenges with inherited genetic conditions like Thalassemia or Sickle Cell Anemia. PGD offers a ray of hope. Specialised fertility clinics in cities like Mumbai, Delhi, and Bangalore use PGD technology to help these couples have healthy children, drastically reducing the chances of passing on severe diseases.
Key Vocabulary
Key Terms
EMBRYO: A very early stage of development of a baby after fertilisation | IVF (IN VITRO FERTILISATION): A process where an egg is fertilised by sperm outside the body, in a lab dish | GENETIC DISEASE: A disease caused by abnormalities in an individual's DNA | CHROMOSOME: Thread-like structures in cells that carry genetic information in the form of genes | IMPLANTATION: The process where an embryo attaches to the wall of the uterus (womb)
What's Next
What to Learn Next
Now that you understand PGD, you can explore 'IVF (In Vitro Fertilisation)' in more detail. Understanding IVF will give you a complete picture of the assisted reproductive technologies that make PGD possible, showing you the bigger journey of how life begins in a lab!
