What is Myotonic Dystrophy?

I couldn't decide whether to write an introduction to Dregan and our family, or Myotonic Dystrophy first. I have decided to write about the disorder, as most of you reading this early on in our journey will already know Dregan!

So, WHAT is Myotonic Dystrophy?

Myotonic Dystrophy (DM) is a genetic disorder, that affects many parts of the body. Unlike other Muscular Dystrophies, it doesn't only affect the muscles, it also affects the Heart, Lungs and Gastrointestinal system. In its more severe form, it affects the Brain. 

Muscular Dystrophy is the umbrella term for over 35 different Neuromuscular disorders - DM is one such (less well known) disorder. It is said to be the most common form diagnosed in ADULTS, and symptoms generally start to show themselves in 20's/30's +. The more severe form of DM is CONGENITAL Myotonic Dystrophy, which is symptomatic from birth, this is the form Dregan has.

DM is one of the most complex disorders known, and it has unique mechanistic features. If you are diagnosed with the disease, one of your parents DOES have it - even if they have not shown any symptoms as yet. There is a 50% chance of the disorder being passed to any children you may have, and in the same way, any full siblings you have also have a 50% chance of inheriting the gene. Recent research has suggested that every person who has the gene can be traced back to just 2 people thousands of years ago!!

So why is it so unknown? 

One of the features of DM is that is called 'Anticipation' - this basically means that the disorder seems to get worse through each generation it is passed on, and so the family may have no idea they carry the gene until a child with severe difficulties is born - as is the case with Dregan. You often find that great grandparents may show no symptoms at all until their old age, where they may get cataracts. This is often ignored, as cataracts in the eyes are very common in the elderly anyway. The Grandparents may start to show mild symptoms in their 50's/60's - but nothing to be overly concerned about. Parents may then start to show symptoms in their 30's, and then the next generation child can be born with the congenital form, and be severely affected from birth.

There is also a bias towards maternal transmission of the congenital form. No-one knows why, as research is still ongoing, but it seems that when a child is born to a mother with the faulty gene, the baby is more likely to inherit CDM. This was the belief until only recently, and it seems from research I have done, it was only realised in approx 2006 that the congenital version could be passed on from the paternal gene. I am still looking into it, but it seems there have only been 6 recorded cases in the years since.... 7 now. This does not mean that there have not been more, but this is all that we have found on record. Research is still ongoing, but on many sites you read, they will say it is only passed on by the mother, which is incorrect.

How does it affect the Genes?

The best way to explain it is how Dregans consultant tried to explain it to him. Imagine you have a Lego set, and the instruction booklet tells you how to make the set. You follow the booklet, you get a perfect model at the end. The booklet is your DNA/Genes and the finished model is you! One of the pages in the booklet (the chromosomes) is repeated over and over again, and the more the page is repeated, the harder it is to complete the Lego set - you can't build the model properly, because the instructions are wrong. Dregans pages are repeated a LOT - we are waiting for the official number, but the Consultant says over 1000 times.

In a more Sciency language: The Genes responsible for DM1 are found in Chromosome 19. Each Chromosome consists of a long chain of chemicals that form DNA. The disease is characterised by stretches (repeats) in this DNA. In healthy people the repeats are between 5-37. 38-50 repeats show you carry the gene, but will never show symptoms, but can pass it on. If you have over 50 repeats you WILL show symptoms in your life and the disease WILL affect you. As mentioned above, Dregan is thought to have over 1000 repeats.

How serious is it?

It is a very serious progressive condition. It is not possible to predict how and when the disease will become symptomatic, however, the younger you are when it begins to affect you, and the more repeats you have, is indicative of how severely you will be affected. 

Putting it into context for Dregan, as this is his blog, he has a very severe form of the disease. The Consultant has been very clear that although it is impossible to say how he will progress, he WILL deteriorate, and he needs close monitoring. He is only 15, and is currently showing almost all the symptoms of the Congenital and later Adult onset disorder. So he is quite progressed already. 

There are no cures for the disorder, or treatments to stop the progression of the disease. You can have Therapies to help with the symptoms, and some medication is available for help with the Myotonia (inability to release muscles). Unfortunately it seems this just masks the symptoms, and doesn't halt progression. We are still in early days, so all this is still being put in place for Dregan, as he has tests and investigations to see what is appropriate.

It is a degenerative, progressive disorder. It doesn't 'kill' you in the way a disease such as Cancer will kill you, but the complications of the heart/lungs/muscle wasting can cause life expectancy to be reduced. In severe cases this is a significant reduction - but that's for another day. Lets not forget the affect it has on day to day living for the person with the disease, and everyone who loves and cares for them. It can have a devastating effect on those it touches. 

So, a long post there, if you have got all the way to the end, give yourself a gold star!!! 

There is LOTS I have missed out on, for more information these websites are very helpful:

http://www.myotonicdystrophysupportgroup.org/

http://www.myotonic.org/

I am sure there will be more to follow, as we learn more and how it is affecting my Bear, but for now, Thanks for taking the time to read.

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