Q. What is PGD ?
PGD is a technique used during IVF-ET, where embryos are tested for disease genes and only healthy embryos are transferred into a womb.
Q. PGD – How is a diagnosis made ?
Embryos are obtained by combining eggs and sperm in the laboratory. From each embryo, one or two blastomeres are removed and tested. If the embryo is judged to be free of the disorder, are transferred to the uterine cavity.
Q. Why is PGD performed ?
Couples either with genetic disease or a carrier do not want to pass their disorder on to their child / children. Prior to PGD for those couples who has no choice but to pass their defective genes to off spring, but with the help of IVF – ET and PGD embryos free of the genetic disorder can be transferred to the uterus and once implanted couple will have child free of genetic disease.
Q. What are the indications for PGD ?
Indications for PGD are :-
– Advanced maternal age ( > 35 years)
– Recurrent miscarriage.
– Repeated IVF/ICSI – ET failure cycles.
– Unexplained infertility.
– Male factor.
– Known genetic causes.
Q. How many genetic disorder can be tested with PGD ?
PGD is used to diagnose number of genetic disorders for eg :-
– Sex linked disorders like Hemophilia, fragile x syndrome, neuromuscular dystrophies, rett syndrome, vitamin D – resistant rickets.
– Single gene disorders like, down syndrome, cystic fibrosis, sickle-cell-disease, thalassaemia
Q. How accurate is PGD or Does PGD eliminate the need for amniocentesis or other prenatal screening ?
The only limitation with PGD is mosaicism – if with in the same embryo a two different blastomeres in which one is normal and the other is abnormal then the PGD result is correct but we are transferring the abnormal embryo. So as genetic testing improves we will eventually be able to eliminate prenatal test like amniocentesis.
Q. Will PGD – basically wipe out genetic disorders ?
We cannot cure the person with genetic disorder, but can hopefully stop genetic disorders from being transferred through out generations and we have the opportunity to greatly reduce the number of children born with these genetic diseases.
Q. How long this PGD technology been used, and is it safe ?
In 1989 Handy side & Colleagues first used the PGD for X-linked disorder in London. Since then about 1000 PGD babies have been born around the world and no increase in anomalies was observed.
Q. What are the first steps for PGD at your centre ?
At our centre Couple first refer to a Genetic counselor for a complete counseling. If necessary, and not done before genetic testing is done before the IVF-ET procedure. Once enroll in IVF-ET PGD program, we begin IVF & the subsequent PGD process.
Q. What does PGD involve ?
PGD involves an IVF/ICSI-ET. Interested couple Undergo an IVF/ICSI cycle where eggs and sperm are either inseminated or injected for fertilization and from resultant embryos one or two blastomeres are removed to check the genetic abnormality. Blastomere biopsy done at 6-8 cell embryos and it is very safe as at this stage cells are not in the process of forming specific parts of the placenta or fetus, and removal of some cells does not cause fetal or congenital abnormalities.
After the biopsy the embryo are kept in culture media for further development till the result comes. Once the results are ready, the 5 days old embryos called blastocyst which are free of genetic disease are transformed to woman’s womb.