At the beginning of my pregnancy, genes were the subject of choice. Osteogenesis Imperfecta (OI) is a genetically dominant condition. People with OI typically have a 50% chance of passing on the condition. The typical part assumes that the person you’re having a child with doesn’t also have OI. Thus, our very atypical situation.

My husband and I both have OI, but we have different types. He has Type IV OI an

d I have Type V. Complicating matters further, my type is a completely different collagen abnormality. The location of the genetic mutation for Type V has not yet been identified. Therefore, the usual genetic tests to confirm the presence or absence of OI don’t work for people with Type V. We knew from the start of our journey that we’d like to learn as much as possible about our baby as soon as possible so we could be best prepared.

We also knew the odds. Like two people with two different types of dwarfism (or any other genetically inherited condition), a parent can only pass on his or her type. The variation in that type could be significant, but it would still be one of two types (Adam’s Type IV or my Type V).

So the baby would have a 25% chance of inheriting Type IV, a 25% chance of inheriting Type V, a 25% chance of inheriting both, and a 25% chance of inheriting both our normal genes-and NOT having any form of OI. If a baby inherits both OI genes, double dominance is the result. The dwarfism community has done an excellent job educating and supporting each other on this difficult outcome. For us, double dominance was the most concerning possibility because babies that inherit both dominant genes generally do not survive. Some researchers speculate that the conception and pregnancy under this circumstance may often not result long enough for awareness because the body recognizes the severity of the abnormality.

One of the few labs in the country that tests for OI was consulted on our situation. They replied that there were no other cases documented cases like ours to use for comparison. Based on the fact we’ve both had genetic testing before though, they hoped to be able to find out whether our baby has OI through a chorionic villus sampling test (CVS).  Under most circumstances, a CVS could be used on its own to render results but my Type V OI would have to be ruled out by comparing her genes to mine. I’ll write more on our experience with a CVS and the many emotional/psychological aspects surrounding this whole issue, but I thought it appropriate to start my blogging journey by addressing the first question most people have for us-whether or not they ask.

Now on to a more pressing matter as of late…jeans. I normally wear kids’ sized jeans and pants. Thanks to the absence of a children’s maternity section, my pants selection is becoming sparse. I did, however, discover this ONE last pair that will button. I wore these in high school after my spinal fusion so they were large enough to fit me AND my hefty back brace at the time. I knew there was a reason I kept those!

And here they are…the last surviving jeans!

[Photo caption: Belly shot at 24 weeks (6 months). Click on picture to enlarge...if you dare!]

Tags: genes, mutations, osteogenesis imperfecta, pregnancy

This entry was posted on Monday, March 15th, 2010 at 2:10 am and is filed under fashion, genetics, maternity, osteogenesis imperfecta. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.