A Little More About PGD

To keep my mind off of tomorrow's impending Beta, I thought I would type out a quick post about PGD. I also wanted to document the fact that I am not as abnormal as some of you may think (well not in this way, at least).

Soon after the PGD results came in, Angie asked (and some of you may have wondered) why so many of my embryos were deemed abnormal. First off I want to clarify (as I have done in the past, but I think it bares repeating, because this is a confusing topic), when I say abnormal, I don't mean that the embryos have a propensity for some ailment. This isn't Gattica. These are chromosomally abnormal embryos which have too few or too many chromosomes and would probably not live past birth, or if they did, it would not be for long. In past cycles someone asked me how many of the abnormal embryos might somehow "grow out of it" and be healthy babies. The answer is none.

I asked Dr. Internet why so many of my embryos (60%) were chromosomally abnormal and if this is rare. Dr. Internet gave me this article. It talks about young egg donors (fertile women in their early 20's) and how they are finding even young, fertile women have a surprisingly high number of genetically abnormal embryos produced from an IVF cycle. For those of you who don't care to wade through the entire article, I have excerpted the relevant portions:

The present study indicates that young donors, presumably fertile, produce high rates of chromosomally abnormal embryos (57%). Nevertheless, because they produce many oocytes, there are enough chromosomally normal embryos to result in high pregnancy rates after IVF. The findings of this study suggest an unexpectedly wide range of chromosome abnormality rates between donors, but similar rates and variations are found in younger infertility patients.

The comparison group of infertile patients, 18–34 years old, undergoing PGD, produced 66% chromosomally abnormal embryos, higher than the egg donor group. However, considering that this comparison group was 5 years older, on average, than the egg donor group, one can assume very similar rates of chromosome abnormalities for the same age. This, if true, would mean that infertility in young couples (<35) may be attributed to other factors, and not to chromosome abnormalities in oocytes. One may also consider that it is certain aspects of follicular stimulation that could possibly cause aneuploidy in both donor and patients eggs. Whatever the reason, true controls such as analyses of eggs from donor and patient embryos in natural cycles are not available.>

So, it looks like my 60% rate is just about average. I don't know why, but this makes me feel a little better. I know most (all?) of you probably don't care, but for my purposes of making this a complete journal, I am summarizing the PGD results below. It is important to note that they don't test all chromosomes, just the 9 most commonly associated with miscarriages. For reference, a genetically normal embryo has two copies of each chromosome, trisomy means the embryo had three copies of that particular chromosome, and monosomy means it only had one.

Embryo 1: Trisomy 14 and 18.

Embryo 2: All tested chromosomes normal.

Embryo 3: Trisomy 14 and 17 and Triple X Chromosome.

Embryo 4: All tested chromosomes normal.

Embryo 5: Trisomy 13, 14, 15, 18, and 22 (this one they call "complex abnormal").

Most of these trisomies would have caused a first trimester miscarriage, had the embryo implanted at all (which is unlikely) but others commonly cause later term miscarriages. For those really interested in this topic, I found an interesting chart on wikipedia.