Whole Exome Sequencing Results

My 7 year old daughter was first identified as developmentally delayed when she was 12 months old. Over the years, she has had a lot of testing for various diagnoses, but the tests always come back negative. So we know lots of things that she doesn't have, but have no explanation for her delay. There have been several times that we were just *sure* it was this or that, and then it wasn't. A lot of the tests are sort of subjective, like for apraxia or autism. But some are more conclusive. She's had genetic testing in the past too, but all came back negative.

In December, we went back to genetics for a 3 year follow-up, and they offered us Whole Exome Sequencing, which was not available last time we were there. They did tell us that in our case, with autism-like symptoms, the chances were quite low (about 5%) that they would find anything of interest. And that the test is super expensive if your insurance doesn't pay for it (and a lot don't because they still consider it "experimental"). It turned out that in our case, it would be completely covered (not even a copay!), so we went ahead.

The results just came back (it takes several months), and they do show that my daughter has a mutation in a specific gene which codes for a sodium ion channel which is active on nerves in the cerebellum. My daughter's mutation was not inherited from myself or my husband, but was de novo. Apparently, if a mutation in this gene makes the channel turn on too much, then it causes seizures/epilepsy, and if it makes the channel turn off too much, then it impedes the interaction of the nerves, causing difficulties with motor, speech, attention, and cognitive skills.

After all this time, it is kind of shocking to actually have an explanation and a mechanism for her difficulties. But it is definitely comforting to have a real diagnosis. I have already found a Facebook group for families with mutations in this gene (though most of them seem to have the epilepsy symptoms, which we do not). I also think that when you know a mechanism, there is a possibility of a treatment down the road that might help.

I just wanted to share this experience, in case anyone else is considering Whole Exome Sequencing.