PGD is a method of determining the genetic
characteristics of the embryo before replanting. There are two methods for the
diagnosis of the embryo.
First method is biopsy, it’s a removal of a single
cell embryo for the research. A biopsy performed on 3 day of embryos life, at
this time the number of cells from 4 till 10 and they are not differentiated, identical,
interchangeable and remain active at the stage of division. After sampling cells,
the embryo must begin to develop more quickly to do not lose the speed of
development. That is why we watching him a few days more to be sure. If
everything went well, and the embryo is developing normally - it starts taking
endometrium mother.
Second method
is visual assessment by using embryoscopy. This method of diagnosis is also
quite outcoming, but is heavily dependent on the human factor - experience and
professionalism of the doctor.
Accuracy of
diagnostic are higher by using biopsy but still not 100% garantide. The reason for the error is that
sometimes assembled to study cell may have different characteristics than the
other cells of the embryo. Scientists says, that he risk fence for blastomere
of the embryo is a minimalistic (first addition from 1989, since that time
statistic being collected).
PGD is
literally translated as "Preimplantation
diagnosis". I.e. It allows to determine the genetic characteristics of
embryos before replacing, such as : health, genetic markers, the child's sex. For
example if woman has had repeated
miscarriages or fetal fading PGD allows to choose the strongest embryos for
replacing. But we must take into account the fact that the probability of
successful conception PGD is slightly reduced. According to the research: the
success rate of IVF 38-40%, and for IVF with PGD - 25-28%. Therefore, if you
are not in a sort of genetic diseases, didn’t have a numerous fading fetus, you
are less than 40 years - we recommend to abandon the blastomere biopsy.
But in some
cases PGD is the best choice, like:
·
Genetic
diseases in your family
·
You
are over 40 years old (the risk of genetic diseases is increase)
·
Prevention
of rhesus fetus, if the parents blood is not compatible
·
If
you need to ensure the birth of a child who would be HLA-matched donor for a
sick family member (using umbilical cord blood).
The last recommendation rarely used by itself, but overall, if you
decide to PGD because of the risk of genetic diseases, and already have
children - it is at the same time the opportunity to choose their HLA-matched
brother or sister. After all, if you did not collect the stem cells of an older
child after birth - the baby's umbilical cord blood could help them both.
I did a research on the point some time ago, and here's what I got to know. Following the birth of the first baby born through IVF where PGD was used, thousands of couples have undergone PGD to increase their chances of having a healthy baby free of a genetic disorder. PGD is used to test for chromosomal abnormalities in embryos including problems with the number of chromosomes (aneuploidy) or structural rearrangements such as translocations. Aneupoidy testing may be recommended for any woman who have had two or more miscarriages, for women over 35who have had a miscarriage or for couples who have had two or more unsuccessful IVF cycles. PGD is also used to test embryos from couples with a genetic disease in their family. These include autosomal dominant disorders, autosomal recessive disorders and X-linked e gene defects, such as cystic fibrosis.
ReplyDeletePGD is is done on day-3 embryos which have 4-8 cells. A small cell or blastomere is removed from each embryo and is tested for the genetic abnormality. The risk of damaging the embryo at this point is very low. Only embryos that show normal results are transferred back to the uterus. Studies have shown there is no increased risk of birth defects following PGD. It is important to remember that:
PGD is not 100% accurate because only one cell is tested. The technique is technically challenging and requires great expertise. Therefore, an amniocentesis or chorionic villus sampling is suggested after a pregnancy is documented.
Also PGD testing ranges from approximately $2k to $5k and is not covered by most insurance companies. Not all IVF centers do PGD. The experimental techniques require great expertise and should only be done by qualified personnel. It is preferable if the lab performing PGD has a trained medical geneticist responsible for the PGD laboratory. If you are considering doing PGD, make certain the laboratory is experienced, does a large number of cases, and is certified. Ask your doctor at the IVF clinic or the lab director the following questions:
ReplyDeleteWhat training has the PGD laboratory personnel who are performing the testing have? How long have they been doing the procedure? When will you get the results of the PGD? What will happen if all the embryos are genetically abnormal? What the clinic’s success rate is for frozen embryo transfer following embryo biopsy? Hope this helps.
If you are considering doing PGD, you'd better make certain the laboratory is experienced, does a large number of cases, and is certified. Ask your doctor at the IVF clinic or the lab director the following questions:
ReplyDeleteWhat training has the PGD laboratory personnel who are performing the testing have?
How long have they been doing the procedure?
When will you get the results of the PGD?
What will happen if all the embryos are genetically abnormal?
What the clinic’s success rate is for frozen embryo transfer following embryo biopsy?