Chapter 4: What is CMT
Well from what I have gathered and learned CMT is a hereditary condition that affects the peripheral nervous system, mainly in the feet and lower legs and hands and upper arms, but there are many different variations, and different ways CMT may become present in your genetic code. CMT is the most common of the neuropathy disorders affecting 1 in 2500 people. So let's go through some of the ways it can be passed down and some of the different variants.
CMT can be and is usually passed from parent to child. This can mean that one parent may pass on the mutated gene to their child, this is in a autosomal dominant. Another way is both parents have an abnormal gene which causes the mutation of the gene in the child, thus in a recessive fashion. You can also get CMT inherited in a X linked way, so the gene is located on the X Chromosome. You can also have no apparent history of CMT in your family and the gene is a de novo gene that appears in conception. In order to find out which type of CMT you may have you need to have genetic testing done, this will give you the type and the variant of that type. People with CMT have a higher possibility of passing on the mutated gene to their children but this does not always happen. I know a family who has CMT and it very much affects their ambulation, but the mom and one son have the disorder while the other children do not.
Their are basically five types of CMT. Each type affects people differently and even people with the same type are affected differently, there is no road map for this disorder, which as a parent who has not experienced this is very frustrating because I don't know how to best prepare my child. CMT1 affects the myelin sheaths of the nerves, the coating surrounding the nerves. This generally affects different proteins, that are needed for producing or creating myelin sheaths. CMT2 affects the axon of the peripheral nerves rather than the myelin sheath. CMT3 is rare and is a severe demyelination of the nerves, it starts in infancy and affects childrens peripheral nervous system and their sensory processing. CMT 4 has various subtypes and usually presents in childhood with walking problems and progresses to the point where they cannot walk any longer ( reading up on these is terrifying because we don't know what type and sub type my son has or whether it's going to progress quickly or slowly!) CMTX is a mutation from the mothers side of the the genetic code which affects the Schwan Cells that wrap around the Axon creating a myelin sheath. So this is what we are looking at but until we get the results for the genetic testing we won't know, when we do then we can better prepare ourselves and Teddy for things he may need to watch for in the future.
So if you've read the previous chapters of this blog you will know that we have noticed this about Teddy since he was walking age. He had always struggled to maintain his balance, and preferred to crawl over walking. He didn't start walking until he was almost 18 months but he was pulling himself up at the appropriate milestone age. But he suffered from severe ear infections until he had bilateral tubes put in his ears at 21 months of age. And after the tubes he was all off balanced again, but we were told to expect that as the tubes could affect his equilibrium. Then we were worrying about the turning in of his feet, his big toes were almost folded under his others and he seemed very flat footed. The other sign was that child would trip over air, we'd be walking along and all of a sudden he'd be down on his knees yanking my arm down as he fell. It was frustrating, because there was no reason for it. Then the Physical Therapist let us know he has what is called Drop Foot, they told us not to google it because there are thousands but the top three are scary. (Google why do you do that to parents?) So then we headed to the neurologist and now we have a diagnosis. Is it 100% concrete? Could something come up in the genetic testing that could change it? I mean anything can happen, and I am hoping for the best possible outcome, but keeping myself grounded in reality.
And my reality changed on February 28th, its been an adjustment, but we are going to get through this, we are going to be fine, and Teddy will continue to be the happy little boy he is!
For more info these have been some helpful sites and I am now an avid Pinterest Pinner for my own ideas of projects we can do to keep him using the skills he has!
National Institute for Neurological Disorders and Stroke
CMTA
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