I can't quite be certain, but it seems as though the researchers who've written about an atypical, SCN4A-related form of myotonia congenita are referring to the disorder that other researchers have called "sodium-channel myotonia," which I've read about before under its alternate name, potassium-aggravated myotonia. In fact, I've not only read about it before, I emailed my husband with a link a couple of days before my appointment with Dr. January, saying, "This is my guess."
However, I'm still really confused. I looked more closely at Dr. January's report, and he says, "I suspect myotonia congenita associated with a chloride channel alteration, but there are other considerations." Okay, SCN4A is a sodium channel. CLCN1 is a chloride channel. I just don't have a chloride channel mutation. I don't. On the other hand, it's now beyond doubt that I do have a sodium channel mutation. It's true that I'm not a doctor of any sort, but this isn't up for debate. Laypeople can understand definitions; doctors don't get to rewrite them without a (generally) hard-to-get consensus.
Believe me, I'm thrilled that an expert is ready to put a name to this. But I do find the discrepancies in the language disheartening. I don't know if the doctor misspoke when dictating his report, or if he misread the report from Athena.
Hopefully, the EMG results in a couple of weeks will be clear cut and leave no room for confusion. I'm trying to figure out just how to ask about this diplomatically if they do, or if the language still leaves me confused.
Friday, January 28, 2011
Thursday, January 27, 2011
Links to Information about Atypical (SCN4A-Related) Myotonia Congenita
From the NIH National Center for Biotechnology Information site, about halfway down the page, under "Mapping":
In a family with acetazolamide-responsive atypical myotonia congenita, Ptacek et al. (1992) found linkage to SCN4A; maximum lod score = 3.56 to 4.19 at theta = 0.0, depending on assumed penetrance varying from 0.7 to 1.0.
The abstract for the Ptacek, et al., study, "Linkage of Atypical Myotonia Congenita to a Sodium Channel Locus," is here.
In a family with acetazolamide-responsive atypical myotonia congenita, Ptacek et al. (1992) found linkage to SCN4A; maximum lod score = 3.56 to 4.19 at theta = 0.0, depending on assumed penetrance varying from 0.7 to 1.0.
The abstract for the Ptacek, et al., study, "Linkage of Atypical Myotonia Congenita to a Sodium Channel Locus," is here.
Tuesday, January 25, 2011
Part of Conversation with Dr. January at First Appointment
Me (kind of tearily): Ever since I got the genetic testing back, I've been so worried that I've given my son, this active, hiking-all-the-time kid, some crappy disease.
Him (kindly, but very firmly): Hold it right there. You didn't give him anything. If he's smart and good looking, you didn't give him that, and you didn't give him this. It's the luck of the draw. If you have some kind of original sin or guilt, you need to take those issues somewhere else to deal with.
It was exactly what I needed to hear, and my husband and I burst out laughing.
Him (kindly, but very firmly): Hold it right there. You didn't give him anything. If he's smart and good looking, you didn't give him that, and you didn't give him this. It's the luck of the draw. If you have some kind of original sin or guilt, you need to take those issues somewhere else to deal with.
It was exactly what I needed to hear, and my husband and I burst out laughing.
Monday, January 24, 2011
A Suspect! Myotonia Congenita, We Have a Few Questions for You.
The appointment today was wonderful. Dr. January at the University of Pennsylvania took me very seriously and believes he knows what the problem is. The physical exam he gave was the most thorough I've ever had, as was the medical history he took.
He's ordered a few blood tests, which he expects to be negative (and, in fact, I've had them more than once before and they have always been negative). He also ordered an EMG that he will perform (remember, this is at a premier EMG lab), and I'll have that in a couple of weeks.
The suspected culprit is myotonia congenita. [Edit: I had this wrong when I first wrote up this entry; I thought the doctor was talking about paramyotonia congenita, mostly because the gene almost always associated with myotonia congenita is CLCN1; SCN4A is associated with paramyotonia congenita. However, I just got a copy of the report today; right there in black and white, Dr. January says he suspects "myotonia congenita." I did a little digging and found a couple of studies saying atypical cases of myotonia congenita can be caused by mutations in SCN4A.]
I was very active as a child, teen, and young adult, but Dr. January didn't seem to be surprised or bothered by this. (I do recall the sensation of muscle tightness even as a child, but it didn't slow me down, and I didn't know it might be abnormal.)
The doctor also said that the symptoms of myotonia congenita can be managed, and that there are better drugs available to treat the muscle tightness than any I have tried.
The news that this disease can be managed is the best news of all. It was a tremendous relief to hear that even if my son is at risk for this disease, his quality of life will not necessarily be compromised even if he develops it.
I'll let you know the results of the EMG in a couple of weeks; I'm expecting to see something (after all, I've already had one abnormal EMG), but I'm not sure what. I also don't know if the kind of activity seen will make a difference diagnostically.
He's ordered a few blood tests, which he expects to be negative (and, in fact, I've had them more than once before and they have always been negative). He also ordered an EMG that he will perform (remember, this is at a premier EMG lab), and I'll have that in a couple of weeks.
The suspected culprit is myotonia congenita. [Edit: I had this wrong when I first wrote up this entry; I thought the doctor was talking about paramyotonia congenita, mostly because the gene almost always associated with myotonia congenita is CLCN1; SCN4A is associated with paramyotonia congenita. However, I just got a copy of the report today; right there in black and white, Dr. January says he suspects "myotonia congenita." I did a little digging and found a couple of studies saying atypical cases of myotonia congenita can be caused by mutations in SCN4A.]
I was very active as a child, teen, and young adult, but Dr. January didn't seem to be surprised or bothered by this. (I do recall the sensation of muscle tightness even as a child, but it didn't slow me down, and I didn't know it might be abnormal.)
The doctor also said that the symptoms of myotonia congenita can be managed, and that there are better drugs available to treat the muscle tightness than any I have tried.
The news that this disease can be managed is the best news of all. It was a tremendous relief to hear that even if my son is at risk for this disease, his quality of life will not necessarily be compromised even if he develops it.
I'll let you know the results of the EMG in a couple of weeks; I'm expecting to see something (after all, I've already had one abnormal EMG), but I'm not sure what. I also don't know if the kind of activity seen will make a difference diagnostically.
Saturday, January 22, 2011
Specialists' Specialists
My neurologist looked at the results of my genetic testing and suggested I see a specialist he really respects. I'll call her Doctor Very Busy. Unfortunately, according to Doctor Very Busy's receptionist, I could only get on the waiting list for an appointment.
My general practitioner was doing his own research at the same time, at came up with two names. The first name was that of a specialist who could see me in June. I'll call him Doctor June for now, but I'll change his name in a bit. The second name was that of Doctor Very Busy. Turns out I wasn't even on the waiting list to see Doctor Very Busy - because there is no waiting list. Doctor Very Busy has decided to limit her practice to ALS patients. So my general practitioner asked to whom Doctor Very Busy recommended patients she couldn't see go, and was given a name. My amazing general practitioner got me a February appointment with the recommended doctor, so I'll call that doctor Doctor February.
Earlier this week, I got a phone call from Doctor June's receptionist. Doctor June had an opening; could I come in on Monday? Yay! Doctor June is now Doctor January. And Doctor January heads one of the most prestigious neuromuscular research centers in the country.
I'm quite excited; I really do think I am getting close to a real answer now. (Remember, CFS is a syndrome, so it doesn't explain anything causative - an underlying disorder, such as a genetic disorder, can cause the physical symptoms that get labeled CFS.) I'm also a bit nervous. "Important" doesn't begin to describe the significance of at least one of these upcoming appointments.
My general practitioner was doing his own research at the same time, at came up with two names. The first name was that of a specialist who could see me in June. I'll call him Doctor June for now, but I'll change his name in a bit. The second name was that of Doctor Very Busy. Turns out I wasn't even on the waiting list to see Doctor Very Busy - because there is no waiting list. Doctor Very Busy has decided to limit her practice to ALS patients. So my general practitioner asked to whom Doctor Very Busy recommended patients she couldn't see go, and was given a name. My amazing general practitioner got me a February appointment with the recommended doctor, so I'll call that doctor Doctor February.
Earlier this week, I got a phone call from Doctor June's receptionist. Doctor June had an opening; could I come in on Monday? Yay! Doctor June is now Doctor January. And Doctor January heads one of the most prestigious neuromuscular research centers in the country.
I'm quite excited; I really do think I am getting close to a real answer now. (Remember, CFS is a syndrome, so it doesn't explain anything causative - an underlying disorder, such as a genetic disorder, can cause the physical symptoms that get labeled CFS.) I'm also a bit nervous. "Important" doesn't begin to describe the significance of at least one of these upcoming appointments.
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