Lisa,

I understand your hesitation to put your children through an EMG. A good pediatric neurologist should be able to do it quickly and they only need to look in one muscle group (usually the palm but it can be biceps, calves, etc). If they have myotonia, even if there are no visible symptoms, it will be obvious right away.

The reasons to consider testing would be so they can wear Medic Alert jewelry in case of an emergency (so that they aren't given dangerous anesthetics), so their teachers will be more understanding, and so that they can get appropriate medications if the myotonia becomes severe.

On the other hand once they are diagnosed they will never be able to get private health insurance, they won't be able to serve in the military, and public schools will try to put them in special ed programs even though they have no mental deficits (they get more government money for special ed).

My daughters were not officially diagnosed. They do have it in their records that we have a family history of myotonia congenita, so their doctors are careful about anesthesia and certain medications. Because of that, one has a great career as an officer in the Air Force which wouldn't have been possible if she had a written diagnosis.

It's a tough decision. If you want to do the DNA testing, you can join the Periodic Paralysis Association at www.periodicparalysis.org and get it done for free. Your doctor will have to fill out the paperwork on the site to order the test, and he will have to request the results (which can take up to 2 years). If you don't request results you will never know because it's considered a research project.

Dr. Lehmann-Horn's lab in Germany is the only one in the world that I know of testing for the different known mutations. Last I heard there were over 60, but that's probably gone up.

If your husband is the only one in his family with MC (other than siblings), then he probably has Becker's myotonia, and in that case your children would have almost no chance of inheriting it. But if he has an aunt or uncle, cousin, grandfather, etc who had stiffness, then it's probably Thomsen's and they would have a 50% chance of getting MC.

Let me know if I can help you with any other information -

Jan

Thanks for the info!
My husband and two of his three brother have myotonia. My father in law also has this. The way I understand the genetic inheritance, it is likely Becker's. Is that correct.

I hadn't thought of the insurance or military issue. Thanks for raising those points. I will have to give this further consideration.

We have recently moved and have a new family dr. The kids are going to see him for the first time in the next couple of weeks.

I was look for a good fact sheet to take with me to give to him. I find many family Dr. are not very knowledgeable about this. Do you know of any good ones??? I have downloaded the NORD factsheet, but it is very generic.

Thanks!

Lisa,

If your father-in-law has myotonia, then it would almost certainly be Thomsen's, and that means your children have a 50% chance of inheriting it.

Thomsen's tends to show up a little later (around puberty) and may just seem more like clumsiness at first. Becker's is usually noticeable at 2-3 years and seems to be associated with more hypertrophy of the muscles at a young age.

I don't know of any fact sheets, but the Quest article listed on my website has a lot of good information. I'll try to put together a fact sheet for people to print out for their doctors. It's so rare that many neurologists don't even know much about our condition.

The most important thing for doctors to know is the possible risk of life-threatening reactions to certain types of anesthesia. Also certain types of medication can make myotonia worse including drugs that lower blood sugar or raise potassium levels.

If I can get something put together in the next few weeks I'll e-mail you so you can take it to the doctor.

Jan

As a child of a parent with mytonic dystrophy I thought I would give you my opinion on getting tested. Personally, I have decided not to get tested until I decide to have children of my own. My parents didn't know it ran in the family until relatively late in my father's life, but with a 50% chance of having it myself, as long as it is not affecting my life adversely, I see no reason to find out. If it starts to affect my life and work, I would get tested, but, now, in my late 20s, it does not yet seem necessary. I just thought that a point of view from a child might be useful. Kate

Kate,

I think you are wise to get tested for myotonic MD before having children. Myotonia congenita is relatively stable throughout generations and it doesn't seem to matter if it's passed on by the father or the mother. The mutation is in the chloride channel of the skeletal muscle, whereas mytonic MD is a mutation in a protein kinase gene that can vary greatly from person to person.

Myotonic muscular dystrophy may be mild or even unnoticeable without an EMG and DNA test if it comes through the father, but if the mother passes on the gene, the next generation is generally worse, and by the third generation through female inheritance there is usually profound weakness and mental impairment from birth. As I recall many babies don't make it past the first few weeks.

I know many families with myotonic MD and the disease progression varies quite a bit. Like your father, many men don't even show signs until they are older (40s or 50s) and may have only experienced slight weakness and stiffness with muscles gradually starting to atrophy in the neck and face. The hormones related to pregnancy can exacerbate symptoms earlier in women and affect the baby.

The DNA testing for myotonic MD is widely available. Unfortunately if we want DNA testing for MC we have to send it overseas and wait for months or even years to get results.

If you don't get tested, I would strongly advise that you get checked for cataracts every year by a good opthamologist (not optometrist). There is a type of cataracts strongly associated with myotonic MD even if other symptoms are minimal.

Thanks for your input -

Jan

Yes, I have read that it can get worse for mothers to children. I also figured that since I was fortunate to know before I had children, I can nip it in the bud in my side of the family. My dad is not sure on which side he got it, but he is clearly worse than the previous family members, and is hardly able to walk anymore (the diagnosis was about 20 years ago, now). I couldn't even imagine having children without genetic testing first, and the information you gave me only makes that more obvious. After all, we don't know when there will be a cure, and I am not going to gamble with my family.
As I said, my dad is getting worse. He has already experienced the sleep apnea, and has developed a heart murmer. He is also so weak sometimes he can't make it down the stairs, and he falls often. On the other hand my aunt only has the thinner face and cataracts which she has had removed. Thanks for keeping me on track about my eyes. Do you think my dad and/or I should wear a bracelet regarding general anesthesia? With all his falling and the number of times he has gone to the hospital, I wouldn't want them to not know he shouldn't be under? He doesn't have one now, but I might be able to convince him to get one if it is a good idea? Thanks. Kate