Friday, October 17, 2008

What caused it?

Ben's deafness is due to mutations on the Connexin-26 gene. It turns out that both my husband and I are carriers of this mutation (who knew?). Any child we have has a 25% chance of being deaf. Ben is our first and only child, so you could say we hit the jackpot on the first try!

The good thing about a Connexin-26 diagnosis is that it's non-syndromic. Sometimes deafness is just one of many symptoms of a syndrome (like Alport's or Long-QT), and often the other symptoms don't appear until later. For example, with Usher's Syndrome, blindness usually starts developing in the pre-teen years. So you're always waiting for the other shoe to drop. With Connexin, there aren't any other shoes. Ben might develop other problems later, but he's at no greater risk than a non-deaf child.

Another good thing is that Connexin kids tend to do very well with cochlear implants. Their hearing anatomy is all present and intact. The only problem is that the hair cells along the basilar membrane, which translate mechanical sound energy into nerve impulses, are defective, due to a lack of Connexin protein.

We had mixed feelings when we got the results of the genetic testing. On the one hand, we were glad to have a definitive cause, and on the whole a Connexin diagnosis is the best. Also, I could stop worrying that I had done something wrong during pregnancy, which was a relief. On the other hand, we both felt a little sad to think that we had given him a bad gene. Then a friend pointed out that probably most people are carrying around at least some mutated genes, and that we probably gave him lots of really good genes, too.

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