(WARNING - lots of boring technical science stuff, it's okay to stop reading here)
So here is the PGD elaboration on why our little snag has turned into a 12 week big blip of a shugamuggie. (i'm going to use this word a lot now, i like how it sounds)
- Fact 1: I'm an RB1 (retinoblastoma gene) carrier.
- Fact 2: If our baby inherits the RB1 gene (50/50 chance of it) there is a 99.7% chance of penetrence meaning they will get it too (cecily is a weirdo anomaly, not that that was really news to anyone...hee hee...but she's an RB1 carrier who did NOT get cancer, so anomaly and lucky to boot)...oh and inherited retinoblastoma also carries a 60% chance of it being bilateral. :[
- Fact 3: Preimplantation Genetic Diagnosis can determine whether or not the fertilized embryos are carriers, so that we are only implanted with 'non-carriers'
Here's where the SUPER complicated part starts. Because they only have one itty bitty (super understatement) cell to work with they need to duplicate it's gene-code. While duplicating the gene-code there can be super small errors. Errors that may result in deletions of certain frames. This would be bad because what they're looking for is a specific frameshift mutation that both Cec and I have which in our case means you're an RB1 carrier and if some frames are deleted on the duplicated gene-code then it may test negative for RB1 even if the embryo is a carrier. Make sense? (i had to read the sentence over again to make sure i had it right)
So... in order to account for the possibility of those errors it would really help 1) to know which parent we inherited it from and 2) to match our parents DNA, Cecily's DNA and my DNA all together so they can compare all the chromosomes and pairs, some of the linkages and frames and make sure they're not missing anything.
Pretty surreal.
So what happens now? Dad is completing his genetics test to see if he's a carrier. (the odd and complicated part being, neither dad OR mom might be an actual carrier-as in RB1 is not written on their gene-code since neither of them had it, it may just be on their gonadal cells) Both Cec and Dad are being sent cheek swab kits to take samples of their DNA. Ryan and I will give blood samples. And from all of that they'll create a panel of tests to be able to screen our single cell biopsies to determine if they're RB1 carriers. 3 weeks from the time they receive our labs till they can give us any updates and then about 8-9 weeks to create the panels and tests.
WHEW.
any questions? ;) hope you enjoyed the genetics lesson of the day. anyone still awake?
definitely learning something new everyday,
stace

