One day I opened the mailbox and found a letter from Emmy's neurologist. I had been waiting for this paperwork even though I knew it wouldn't tell me much about Emmy's prognosis. For some reason I NEEDED to know the genetic test results. I all of a sudden wanted to become an expert in MECP2 mutations. It must be a control thing. I had no control over the fact that my little girl was slipping away and I needed control over something.
I opened the envelope and proceeded to read a report from the University of Chicago genetics lab that had run the test. Ummm, what the *&)% is c.30_31delCG? Having only touched on genetics in my college biology courses I was completely lost. The whole report read as if it was in a foreign language.
Let me back up a little. In most cases of Rett Syndrome, girls have a mutation on a gene called MECP2. For those as fuzzy as me on the topic...girls have two X chromosomes, boys have an X and a Y. MECP2 is located on the X chromosome. Girls with Rett have one X with a healthy MECP2 gene and one X with a mutated MECP2. When boys have a mutated MECP2 gene on their X, they are much more severly affected. Most do not survive. That is because they don't have the back up copy of the healthy MECP2 gene. When a girl is conceived and cells are multiplying something called X inactivation occurs. In each cell in their body one X is shut off and one X stays on. This accounts for the various severity levels in girls. If a girl happens to have more of the non-mutated X's turned on, their symptoms are milder. It is very difficult to test for X inactivation patterns because blood taken from your arm may not reflect what is going on in the central nervous system. A girls mutation type doesn't necessarily tell you the course of the disease either, because of X inactivation.
Basically, finding out the mutation type wasn't going to tell me anything but I still needed to know.
After a LONG conversation with a genetics counselor, I now know what c.30_31delCG means. I'll try my best to describe it in simplest terms. Take a piece of paper and draw a long line. This is the MECP2 gene. Along this gene there are hundreds of thousands of things called neucleotides. The neucleotides are denoted by either an A, T, C or G. Each gene has a different letter sequence but the letters need to be in a specific order for the body to read the gene correctly. It's amazing stuff. Well, on Em's gene the C that is supposed to be number 30 in the sequence and the G that is supposed to be number 31 are missing. Because these two TINY little pieces are missing the body can't read the gene correctly. Now, people have different letter sequences on their genes all the time without any problems. As the geneticist put it, that's what makes people unique. But girls with Rett happen to have these mutations in a very sensitive part of the gene. I could keep going but I'll stop there. My brain is starting to turn mushy as I re read this trying to determine if I'm explaining it clearly.
So there is the science lesson for the day. The body is an amazing thing. And, I've learned that even though I understand the genetics behind Rett Syndrome...I still have no control. I have to just let go and enjoy the ride.