Warning- kind of a long post ...
We spoke to the genetic counselor again this morning because the CGH analysis is complete. The results, while good, are a bit ambiguous.
(CGH microarray looks for additions or deletions to each specific chromosome. If a chromosome has more or less than it should, it will show up in this test. The test will not, however, show if there is a translocation or inversion. That is, if a piece of a chromosome breaks off and flips over before sliding back into its original place. Or, if 2 pieces of a chromosome break off and trade places. In both cases, the chromosome would appear to be the right size, but the genetic material is flipped around.
CGH is typically used prenatally to determine if the baby has a specific genetic condition whose location is known. Or, it is used to test the parents to see if they are carriers for a specific condition. For example, if you test a baby for Tay Sachs Disease, the geneticist knows exactly where to look for that information- which gene to analyze and what it will look like of it the baby is affected.)
Because we are not looking for any specific condition, the whole picture was analyzed. There appears to be a small piece of the baby's chromosome 16 that is duplicated. Based on the location of the duplication and the specific material that is duplicated, there is no known affliction that they can say the baby has.
The geneticist also has our blood samples to use as a comparison. So, when they found this duplication, they automatically compared it to our chromosome 16's to see if either of us may have passed this duplication on to the baby. Turns out, Matt has an identical duplication on his chromosome 16.
Because Matt is a normal, healthy person, they are pretty certain that the duplication is not causing the baby's issues. Duplications such as this are not uncommon, and 99% of the time they are not of concern.
There is a threshold by which they measure such things to determine if the duplication of clinical significance. If the duplicated area is small enough, and a parent has clearly passed on the duplication, they will say that the duplication is clinically insignificant. The duplicated area in this case is a little too large for them to say that it is clinically insignificant. However, the duplicated area in the baby is the exact same size as that in Matt's DNA, so we have every reason to believe that it is, truly, insignificant.
At the end of the day, we really have very little new information. They have successfully ruled out many known conditions based on the testing we have done, many of which have no known association with the problems that the baby has. It appears as if the most likely explanation is that we are both recessive carriers of something that causes cystic hygromas. Because we cannot pinpoint where that recessive gene is, we will most likely not be able to test for it in future pregnancies. However, in an attempt to be proactive where we can, we are most likely going to bank some of the amniotic fluid from this pregnancy so we have a sample moving forward that we can compare future pregnancies against if we come across this again. Hopefully, in the event that we need the old sample, technology will have advanced enough that we be able to test for more things that we are currently not able to detect.
There is one more test they may still run, the uniparental disomy test that was discussed when we had the amnio performed. This goes back to the concern of mosaic trisomy 15 when our CVS results were inconclusive. There is still a chance that the baby's chromosome 15 is not representative of both of our DNA (and both chromosomes came from the same person). The genetic counselor is pretty certain that this isn't what is going on, but we can have them run the test if we would like to rule that out as well. We are still on fence on that one...
We are still praying for a miracle and hoping things can turn around. And most of the time it is encouraging to know that they haven't discovered anything that points to a definitive risk or condition that can be passed down. However, it continues to be really frustrating and disappointing that the tests keep indicating an otherwise healthy, normal baby. There are a couple (literally single digits) of documented cases where cystic hygromas and hydrops have resolved up until about 30 weeks. So, as long as there is a heartbeat, we will be hoping and praying that we can add another to the literature. Please keep praying that this baby can overcome the odds.
Thank you all for your thoughts and prayers! We will keep you posted as we learn more.