With respect to PGD, how do we know that the cell that is removed for the procedure, which I believe represents approximately 15% of the embryo, does not contain DNA or data that may be necessary later in life. In other words, the embryo is in the earliest stages of life, if one were to remove 15% of its structure, how do we know that the remaining 85% of the embryo contains ALL of the necessary ingredients for a developed person. Is it not possible that an embryo requires 100% of its structure in order to insure that the subsequent human has the full range of biological information/data, to support a healthy life.

Interesting question . . . I have no idea what the answer is  But I thought all of the cells are supposed to be the same/have all the genetic info at the stage PGD is done.

pitter-patter:

With respect to PGD, how do we know that the cell that is removed for the procedure, which I believe represents approximately 15% of the embryo, does not contain DNA or data that may be necessary later in life. In other words, the embryo is in the earliest stages of life, if one were to remove 15% of its structure, ow do we know that the remaining 85% of the embryo contains ALL of the necessary ingredients for a developed person. Is it not possible that an embryo requires 100% of its structure in order to insure that the subsequent human has the full range of biological information/data, to support a healthy life.

Every cell in your body contains the entire genetic message so there will be nothing missing.  The cells have not differentiated yet and are omnipotent.

 

 

So what you are saying is that the embryo, in its pre-blastists state, is a fully developed biological entity and that all of the genetic and biological data are fully scripted and contained within each cell, can you please refer me to the peer review medical studies that support your post on the safety of PDG as it pertains to compromising future health by tempering with the cellar structure of the embryo at such an early stage. I realize that this is a relatively new procedure, so I am thinking that your post is an assumption rather than something that had been scientifically proved

 

 

pitter-patter:

all of the genetic and biological data are fully scripted and contained within each cell, can you please refer me to the peer review medical studies

I don't know about a study, but you can find this information in any basic textbook on biology.  Each cell in your body carries 23 pairs of chromosomes, which contain your entire genetic blueprint.  That blueprint was defined at the moment the sperm and egg combined, forming the very first cell, and it is copied in its entirety to every subsequent cell as the embryo grows, continuing to the eventual trillions of cells that make up a complete human body.

This is why genetic information can be obtained from any cell -- for example, a hair found at a crime scene can be used to match a blood sample from a suspect.

pitter-patter:

your post is an assumption rather than something that had been scientifically proved

There are a number of studies supporting the safety of PGD.  Here's a link to one:

http://www.sciencedaily.com/releases/2007/06/070616191628.htm

 

 

pitter-patter:

So what you are saying is that the embryo, in its pre-blastists state, is a fully developed biological entity and that all of the genetic and biological data are fully scripted and contained within each cell, can you please refer me to the peer review medical studies that support your post on the safety of PDG as it pertains to compromising future health by tempering with the cellar structure of the embryo at such an early stage. I realize that this is a relatively new procedure, so I am thinking that your post is an assumption rather than something that had been scientifically proved

Everything that I mentioned in the post is fact and not an assumption on my part.  I did not say that a 'pre-blast' was a 'fully developed biological entity' and I am not sure what that means.  It is a scientific fact that each cell, at every stage of development, including in fully adult humans, contains the complete genetic message.  So a liver cell has exactly the same DNA as a brain cell.  They have differentiated or turned on and off specific portions of the genetic message to form their final forms.  Dolly the sheep was made from a mammary cell.  It is also a scientific fact, that cells from an embryo of 6-8 cells, the stage when biopsy is performed for PGD, not only have the complete genetic message but are undifferentiated and capable of forming all types of tissue (omnipotent).  They are in essence stem cells.  This is why when we take cells out at the multi-cell (ie 6-8 cell stage) the babies are not missing things.  At the blast stage, the cells have begun to differentiate and the part that will become the baby is in the inner-cell mass while the trophectoderm (outter part) will become the placenta and other extra-fetal tissues.  Regarding the peer reviewed studies that support these statements, it is pretty basic and not that new.  Any good college biology text book will have a list of these referrences or go to PubMed on the web and search.

Just as a quick question...wondering if I am thinking of this correctly....it is my understanding that there can be mosaicism in an early embryo.....where a genetic division error can occur.....so lets say this occurs right after fertilization at say the 4-cell stage.....and one of these four cells divides unequally you could in essence have one of the progeny of that fourth cell contain an extra chromosome (like in Downs) and the other cell contain one less chromosome.  So couldn't this result in identifying this embryo incorrectly as unhealthy?  Some of those cells will become the placenta and some will become the fetus...so it is possible that the fetal cells can all be normal and the placenta can contain the abnormal cells......or you could have a scenario where some of the fetal cells are abnormal....causing a problem in the heart for instance (the heart tissues have Down's for example), but the rest of the fetus is normal.  I am thinking this could also give incorrect CVS results as well.

This is how I understood it, but I could be wrong.  I am wondering if this is why PGD is only 99% accurate and why there is a false positive rate......both being due to chromosomal mosaicism and not human error as most people assume since nothing is usually 100%....assumption must be that this is because of human error.  Just curious if this is the case and how often these early chromosomal division errors occur (and if they are more likely to occur in an older mother....????)

You address an important issue. I would love to know the answer as well.