The two labs in the US that do testing are Fullerton Genetics in Asheville, NC and Athena Diagnostics in Worcester, MA. And yes, the testing can make a difference in the treatment. He may have a sodium ion channel myotonia rather than myotonia congenita which may respond better to other medications or to dietary changes. Both labs do a myotonia profile which covers both types (CLCN1 and SCN4A). It's also important to know the pattern of inheritance for family planning (recessive or dominant).

The Periodic Paralysis Association offers the testing through a research lab in Germany. It is free, but has to be ordered by your doctor. You can register on their website, and then go to the "Genetic Testing" section for the forms:

Periodic Paralysis Association

Mexitil can work very quickly. You build up a bit of a tolerance, and then the dose is adjusted, but it usually is not prescribed above 300 mg 3x a day for myotonia. Some younger patients only take it before a sports event, but not on a regular basis. Be sure that he takes it with food or with an antacid. It's important to get the product insert and be familiar with potential side effects. Usually when people don't tolerate it, it's because of the GI symptoms.

I hope you get the insurance approval since it only takes a few weeks to get results when it's done in the US. It can take several months to get the results from Germany, but it will be thorough.

Jan

Type of Myotonia: Thomsen's

Country: US

Spoke with insurance again regarding the labs for genetic testing. Apparently Athena Diagnostics in Worcester, MA is on their list but prior approval is needed.

Did follow up EKG after 5 pills of Mexiletine. My son says he "feels better". Yay, Long time coming!

Type of Myotonia: Thomsen

Country: USA

That's great! It's a life-changing medication for a lot of people.

I hope you get the approval. Tell them it's very important to document the exact type because of the potential of death from anesthesia reactions. My doctors did not take it seriously until I had the DNA confirmation.

Jan

Type of Myotonia: Thomsen's

Country: IS

Life changing for sure. My son can feel a difference when getting up after sitting or laying, but hopes it will eventually do more. I told him to be patient. He just started this medicine and I am sure his doctor wants to see how his body accepts it before any change in dosage. It is good feeling that we are finally on the right track.

Next doctor visit May 2nd.

Thanks so much for the interaction.

Type of Myotonia: Thomsen

Country: USA

Finally getting somewhere with the genetic testing. Looks like Fullerton Genetics in Asheville, N.C. is a participating provider with our insurance. Thanks for mentioning the available labs in the US. I was looking at $5800 with Athena Diagnostics. The insurance would have paid 80% of an allowance ( they claimed not to know allowance amount until billed by lab), leaving me to pay anything over their allowance, plus the remaining 20% and a $ 500 deductible.

I was first informed by my insurance that the only genetic lab listed as a participating provider was Myriad Genetics, Salt Lake City Utah and they do not do myotonia profiles. It wasnt until I mentioned Fullerton, that they found it to be a participating provider.

The call taker at Fullerton was great. She double checked to make sure they would be able to bill a NY resident and supplied me with the CPT codes to give to my son's doctor for prior approval.

Type of Myotonia: Thomsen

Country: USA

I edited my initial reply because I missed your paragraph about the EMG and Mexitil. It's best to start with a small dose and work up to the full dose on the Mexitil. Be sure to read the product insert so you'll be able to recognize potential side effects.

Jan

Type of Myotonia: Thomsen's

Country: US