I dream of genes

From Wikipedia

Last week, we met with a geneticist to learn more about the results of C.'s latest round of genetic testing. Below is everything we learned - apologies if it sounds a bit like Genetics 101.
 
First, based on a family tree she drew on the spot, the geneticist assured us that there was only a very slim chance that C.'s afflictions could be passed on to our grandchildren. It would require that the hubby and I are carrying the same, recessive and very rare gene. Needed next would be for our children to inherit that recessive gene, and finally for them to dig up and marry somebody who is also carrying the same rare, recessive gene. 

So, she is inclined to deem this a "sporadic" mutation - aka de novo. It was a relief to hear this news and we later shared it with our children. 

The geneticist also told us that C.'s latest test results do not seem helpful (posted earlier here). The anomaly that was found can surface either in people with disabilities or in perfectly normal individuals. 

In order to clarify this, hubby and I would need to undergo the same test. If either or both of us are found to have the same anomaly, then it's clearly not the root of C.'s disabilities. If not, then we can only deduce that it is possibly the cause, but not necessarily.

The geneticist explained that this is not always the case. If the child's symptoms are mild - say, for example, Asperger's - then finding the same anomaly in one or both of the normal parents would not prove that the child didn't inherit his syndrome. Because in those instances, it's possible that the parent is simply so mildly affected that he functions normally whereas the child is affected severely enough to be deemed "disabled".

The test they are recommending has a $500 price tag for each of us so we'll only do it if it's covered by our insurance.

We also raised the issue of a blood sample that was sent years ago to Italy to be tested for Rett Syndrome. We already have a negative result from the test for a mutation in MECP2 which covers the vast majority of Rett cases. The still outstanding results are for mutations in CDKL5 which only a small percentage of atypical Rett children carry. 

Our neurologist never chased up that result. Hopefully we will finally get the answer.

The geneticist told us about a more inclusive test, the full exome sequencing - not covered by usual health insurance here - which could track down C.'s genetic culprit. We're unable to shell out the $8,000 that this one costs. Besides, after the geneticist's reassurances about the unlikelihood of this being hereditary, we were dismissive of this option. 

But, then came a surprising revelation that may pique your interest.

For some genetic mutations, there are already treatments that can mitigate - not cure - the symptoms. "Wow" was our immediate reaction. What sorts of treatments they are, I can't say because we weren't given details at this visit. I'll pursue that next time. But this means that the expensive testing could benefit C. herself. (Uh, oh: there's my unrealistic optimism rearing its head again.)

Following our visit, the genetic counselor phoned to say that she and the geneticist had discussed C.'s case further. They concluded that there may be another possible genetic source for C.'s condition. Notwithstanding the notes I jotted down while she spoke, and the searches I've done since, I am still close to clueless on this one. I have only digested the bare basics. We should test C. for "chromosome X inactivation". If she has it, then we'll also need to check our other daughters and granddaughters. 

If I ever clarify what all that means - my daughter the dental student may be of help - I'll post it here.

In the meantime, here is a site I just discovered targeting those of us with un-diagnosed children. There's a questionnaire for a study which I obligingly filled in. It really only takes the 20 minutes they promise it will.