Gia:

If you've had the full myotonic panel from Athena Diagnostic, the first thing I would ask your doctor is, did it turn up any recessive mutations? Some people with recessive mutations on their CLCN1 gene have myotonia congenita even though they only have one recessive mutation (rather than the two typically required of recessive mutations to manifest symptoms). One theory put forth to explain this is something called "copy number variation" where a segment of the gene gets copied and "pasted" back into the gene sequence. If this happens to a segment of the gene with a recessive mutation, the person ends up with two segments of the gene with the same recessive mutation.

Aside from the disorders Jan mentioned, another cause of myotonia like symptoms is something called Brody/Brody's Disease or Brody Myopathy or something of that sort. It's currently considered to be very rare but should be considered in people who have EMG confirmed myotonia for which a CLCN1 or SCN4A mutation can't be found. Additionally, some mutations on the skeletal muscle calcium channel genes can cause myotonia, as well as some mutations on the skeletal muscle potassium channel gene. I think you can find more about that at the Periodic Paralysis Association website.

I know hypothyroidism can cause a myopathy which have been described as presenting as a form of psuedomyotonia. I don't know if it's indistinguishable from true myotonia on an EMG.

Type of Myotonia: Becker

Country: USA

Hi Jenna,

I tried to post a reply to your message earlier and did not see it up. Please excuse if you see more than one incase it shows up later on. Thank you for the information, I will surely look into this. I did not have a genetic test yet or anything to distinquish what type of myotonia I have. I have to wait well into November to see the specialist. They are very booked up in my area. I have had very mild symptoms of myotonia for many many years. Just some stiffness when it is cold or when I do not eat for long periods of time. I do recall one winter where I was out in the cold and was not able to catch my breath. Also, I recall a time where I was splashed with freezen cold water on a water ride at an amusment park where also I was not able to catch my breath right away where others were hit with the cold water and nothing happen to them. I am just confused with the dry eyes and mouth at times and rash along with a slight positve ANA test. Along with the bout of optic neuritis in 2005 and last year a bout of iritis in the same eye. Very very strange. It is the reason I am wondering if Lupus or something like this could cause a EMG to show myotonic symptoms ? It seems that doctors really do not know much about this problem. Thanks and have a great weekend.

Gia

Type of Myotonia: Not sure

Country: USA

Gia:

The genetic testing should give you some definitive answers. From your symptoms, if it is indeed a true myotonia, and I had to guess, I would bet a chloride channel myotonia such as Thomsen or Becker MC, or a sub type called Myotonia Levior...you don't hear much about that last one but it's a very mild, dominant form of chloride channel myotonia congenita.

If you had a chloride channel myotonia, it would usually show up on Athena Diagnostic's test 128, the "CLCN1 DNA Sequencing Test"

If your insurance will pay for it, or you can afford it, I would ask the doctor to test for all forms of myotonia by doing the "Complete Myotonia Evaluation", test, 147, because it can save a lot of time and trouble, and some people have been found to have two different myotonia causing disorders.

As for the other symptoms, it's possible to have myotonia and an unrelated autoimmune disorder, as autoimmune disorders tend to be fairly common.

Type of Myotonia: Becker

Country: USA

Hi

I suffer from the Sjögren Syndrom and Myotonia. My ANA is 1:350 and my eyes are absolutely dry as well as my throat and lungs. I do have stiffness, musclepain, fasciculations and symptoms of a mild periodic paralysis after activities. My EMG shows myotonic (or pseudomyotonic patterns, every doctor says something else). The muscular problems get worse with cold, hunger, stress, infections, menstruation/hormons and injuries.

My bloodresults are all ok, exept the mild increase of ANA, I dont have polymyositis, so it's not prouved that the sicca syndrom has an autoimmune cause. Many family members suffer/ed from the same problems, so it has to be a genetic defect. But up to now they didn't find the mutation, I should do a chromosomal mirco-array, but the costs are not covered.

So I'm living without diagnosis and treatment.

Stephany

Type of Myotonia: unknown

Country: Switzerland