In the March 2006 issue of the journal Acta Neurologica Scandinavica there is an article about VGKC antibodies: IgM-containing fraction suppressed voltage-gated potassium channels in acquired neuromyotonia.
So far, I've only been able to read the abstract. (The university here doesn't carry this journal, and, being a cheapskate, I don't feel like paying the exorbitant fee for access to the article.) According to the abstract, apparently most people who have VGKC antibodies have the IgG type, and for them, it's only the IgG antibodies that affect the potassium channels. But some people have IgM antibodies to VGKC, and for them, it's only the IgM antibodies that affect the potassium channels. Here's the part I found interesting: they conclude that people who test negative for VGKC should also be tested for IgM VGKC. I assume this means that the standard VGKC test only checks for IgG VGKC, but I'm not sure. Maybe some VGKC tests aready check for IgM. Maybe the article will clear all of that up.
This article should be of interest to anyone who has tested negative for VGKC antibodies. I haven't had the VGKC test, but it's interesting to me because I happen to have elevated IgM, so I assume that if I have VGKC antibodies, they're probably IgM.
If anybody has access to the full article, could you please enlighten us?
Here's the full abstract:
"Objectives - Acquired neuromyotonia (ANM) is an autoimmune disorder caused by antibodies to voltage-gated potassium channels (VGKC). Previously, we reported a patient with immunoglobulin M (IgM), instead of immunoglobulin G (IgG), anti-VGKC antibody. The purpose of this study was to determine the function of IgM-containing fraction in ANM patients. Materials and methods - We determined whether anti-VGKC antibodies in the IgG or IgM-containing fractions suppressed outward potassium current (OKC) using the patch clamp method in three patients with ANM. Whole sera from all patients suppressed OKCs. Result - Only the purified IgG, not the IgM-containing fractions from two patients suppressed VGKCs, whereas in a patient with IgM anti-VGKC antibody, only the IgM-containing fractions, not the IgG-containing fractions suppressed VGKCs. Conclusion - Anti-VGKC antibodies belonging to the IgM subclass should be determined in seronegative ANM patients."
Jodi
So far, I've only been able to read the abstract. (The university here doesn't carry this journal, and, being a cheapskate, I don't feel like paying the exorbitant fee for access to the article.) According to the abstract, apparently most people who have VGKC antibodies have the IgG type, and for them, it's only the IgG antibodies that affect the potassium channels. But some people have IgM antibodies to VGKC, and for them, it's only the IgM antibodies that affect the potassium channels. Here's the part I found interesting: they conclude that people who test negative for VGKC should also be tested for IgM VGKC. I assume this means that the standard VGKC test only checks for IgG VGKC, but I'm not sure. Maybe some VGKC tests aready check for IgM. Maybe the article will clear all of that up.
This article should be of interest to anyone who has tested negative for VGKC antibodies. I haven't had the VGKC test, but it's interesting to me because I happen to have elevated IgM, so I assume that if I have VGKC antibodies, they're probably IgM.
If anybody has access to the full article, could you please enlighten us?
Here's the full abstract:
"Objectives - Acquired neuromyotonia (ANM) is an autoimmune disorder caused by antibodies to voltage-gated potassium channels (VGKC). Previously, we reported a patient with immunoglobulin M (IgM), instead of immunoglobulin G (IgG), anti-VGKC antibody. The purpose of this study was to determine the function of IgM-containing fraction in ANM patients. Materials and methods - We determined whether anti-VGKC antibodies in the IgG or IgM-containing fractions suppressed outward potassium current (OKC) using the patch clamp method in three patients with ANM. Whole sera from all patients suppressed OKCs. Result - Only the purified IgG, not the IgM-containing fractions from two patients suppressed VGKCs, whereas in a patient with IgM anti-VGKC antibody, only the IgM-containing fractions, not the IgG-containing fractions suppressed VGKCs. Conclusion - Anti-VGKC antibodies belonging to the IgM subclass should be determined in seronegative ANM patients."
Jodi