Welcome, Luis! I hope you get your results quickly. It is always a relief to have documentation and know exactly what is causing the symptoms. I wish doctors would quit doing muscle biopsies. They are almost always inconclusive and not necessary since DNA testing has become widely available.
Thomsen's can show up at different ages. In my family the most common age was around 8-10, but one of my daughters had some muscle hypertrophy at a young age. Children tend to push against the stiffness to try to force their arms and legs to move, and that causes some muscle damage. When the body repairs the damage, the muscle size is increased to try to deal with the additional stress. It's basically the same thing you see in bodybuilders who rip the muscles on purpose to increase muscle mass after it heals.
If you haven't read the Letter for School Staff on the main page (click on Return to Website above) that might be helpful for your son's teachers. I am going to try to get a Spanish translation because we get many visitors from Spanish-speaking countries.
Ana, glad you got a definite diagnosis! So you would have the recessive form, Becker's MC. That's always good news for people who have children or who want to have children because the chances of them having symptoms is almost zero, even if they are a carrier of the mutation.
Has your doctor talked to you about medications for myotonia? I don't believe mexiletine is available in Spain. Some of the others used to treat MC would be acetazolamide (Diamox), phenytoin (Dilantin), lamotrigene, flecainide, carbamazepine (my least favorite), and quinine sulfate. Diamox and quinine seem to have the fewest side effects, especially for younger people.
Hello! No, I have the dominant form, Thomsen MC. My doctor has not put me treatment yet. My doctor has considered more important, that I first saw the medical geneticist. The geneticist will explain me the chances of transmitting the disease to my children and the problems they may have.
The neurologist told me that after visiting the geneticist visit again to see the ability to get treatment.
I do not speak good English, I hope you can understand me. A greeting!
Do you have two copies of the same mutation? I can't access my genetic database right now, but if G233V is associated with dominant MC, then both your parents would also have symptoms. (Heterozygous is one, homozygous is two.) Is that the case? I haven't ever heard from anyone who had two dominant mutations, but a few have had one dominant and one recessive. That's pretty rare, too.
In the results of my genetic test is written: it has been identified by sequencing the presence of pathogenic homozygous mutation c.698g>T in the gene CLCN1. This change is a "missense" mutation leading to the replacement of glycine by vanila at position 233: p.Gly233Val (p.G233V)
I do not really understand what it means, but my parents did not have any symptom, however, I have symptoms since childhood.
Ana, did you have an EMG showing myotonic discharges? Also, do you know exactly what type of DNA testing was ordered? In the US the gene is usually specified (like CLCN1), but perhaps your lab did a profile looking at several genes.
I don't see that genetic mutation listed in the database for myotonia congenita. However it is a variant associated with Limb Girdle Muscular Dystrophy Type 2A which is on a different gene (CAPN3).
The symptoms could be quite similar earlier in life. I don't know if the lab made a mistake listing the gene or the variant, or if it is a variant for myotonia congenita that hasn't been published yet (very unlikely that it would have exactly the same notation as the LGMD2A variant).
I would suggest contacting the lab or having your geneticist contact them to review the results and make sure they were reported correctly. It's not the first time I have seen misreported test results, so it's worth confirming because they are two entirely different conditions.
If it does turn out to be Limb Girdle MD, there is a doctor in San Sebastian who specializes in LGMD: