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
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.