Genetics Update

Disclaimer: I haven't had a chance to run this by my super-smart friend, Dana, yet. She usually keeps me from saying silly things when it comes to genetics so, Dana, I hope I don't embarrass you with this post! :)

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On Friday, Jeramie and I took Ethan back to Duke for a follow-up with our geneticist. If you remember, I posted back in May about the test results of Ethan's first round of genetic testing. That test was looking at a gene called TBX5 which, if mutated, is known to cause Holt-Oram Syndrome. The test came back negative, which told us that Ethan's 12th chromosome does not contain one of the known mutations. However, a negative result does not necessarily mean that Ethan doesn't have this syndrome (read: false negative). It could be that his 12th chromosome contains a mutation that has yet to be discovered, and it may be years before researchers find it. There is no point in testing Jeramie or me for a TBX5 mutation because it is a dominant disorder. Basically, one of us must have one of the known mutations to pass to Ethan, but since Ethan tested negative, then there's no way we could. Clear as mud, right? Right.

So, where do we go from here?

There's another gene, SALL4, that causes syndromes similar to Holt-Oram. According to our geneticist, there is some overlap between presentations of TBX5 and SALL4 mutations, so it's possible (not probable) that Ethan could have a SALL4 mutation. When Ethan goes into the hospital in November, blood will be drawn for additional genetic testing. It will be sent out of state to be read, and we should have those results by sometime in December. If a mutation in found in Ethan's SALL4 gene, then Jeramie and I will undergo testing to see if either of us carries it. (Remember the de novo rate from my last genetics post? I believe the rate for this particular mutation is 40-50%. So, the chances are still pretty high that neither of us passed it along.)

Just to be clear, I am not at all interested in doing this for the sake of labeling my child with something. As Jeramie and I begin to think about planning for more children, it would be nice to know if we possess a genetic disorder that we could be transferring to our kids. As far as ordering additional tests for Ethan and possibly testing ourselves, we are in a good place. However, we would covet your prayers over the next few months, and especially going into the new year as we begin to talk a little more seriously about #2.

#1 looking cute in the exam room