So a few weeks ago, Evan, Connor and I got our blood drawn to test for these mutations.
From my understanding (which is minimal at best - my lowest score on my ACT by far was the science section), everyone receives genes from both parents to make up their entire genetic coding. These genes are like a set of instructions in making the different proteins in our body.
In Brenna's case, her body began forming, and when it came to the ABCA12 gene, it simply stopped because of the "errors" in the instructions. The ABCA12 gene is responsible for forming the ABCA12 protein that is essential in developing the outer layer of skin (the epidermis). So Brenna's skin lacks this obviously important protein.
Brenna's two mutations are S1249X and R714X. Basically there should be a S and R where the Xs are. Our results showed that I have the S1249X mutation, and Evan has the R714X mutation.
Because we both have one unaffected gene, it acts as a backup and our bodies still produce enough of the protein so that the mutation doesn't affect our skin.
And we learned that Connor is also a carrier; he has my mutation, S1249X. I am two for two in passing along my bad gene vs. my good one. Of course, the chances of him marrying someone with this mutation are incredibly tiny, which is very comforting at least.
So every child of ours has a one in four chance of having Harlequin Ichthyosis. (remember high school biology?!)
- 25% two unaffected genes
- 25% unaffected gene from me, mutation from Evan
- 25% mutation from me, unaffected gene from Evan (like Connor)
- 25% two mutations, resulting in Harlequin
I had really hoped that Connor was unaffected, but we are feeling a little relief now, knowing these definite results. It's a lot to wrap my head around, and I was happy to have the chance to meet with our genetic counselor today to get a clearer understanding. In a sense, it provides a little closure for us about Brenna's condition and why her skin is the way it is...