| Author | Message | ||
     GMF |
Dr. Kanters: During previous communications, I discussed my newborn daughter's LQT3 and ICDs. We just received genetic testing feedback for my wife, son and me. We had Familion Tests by Genaissance Pharmaceuticals. The good news is that all 3 of us are negative for LQT3. The ambiguity of the results are that all 3 of us have the same Class III Variant Found. My daughter's EP recommended that we don't take medications with QT prolonging potential. Although she's currently consulting with other top EPs, she doesn't think they we should take medications. Her doctor said the doctors just aren't fully aware of the effects of the variants. Do you have any perspective about the following results? Class III Variant Found: This test result indicates identification of one or more genetic variants that have been identified previously in normal subjects or are considered common plymorphisms. Such variants are not likely arrhythmia syndrom-causing varients, but the actual significance of these variants has yet to be determined. Whether or not the presence of such variants confers additional risk during exposure to medications with QT prolonging potential is unknown at the present time. Family screening for the presence of such variants is in general NOT recommended but may be considered in families with clearly penetrant familial arrhythmia syndromes to determine co-segration. What kind of genetic testing is performed in your country? Do they test for more than 5 genes? What an adventure...sometimes more answers create even more questions! Take care, Glenn | ||
| Dr. Jorgen Kanters Username: Jorgen Registered: 08-2003 |
Your situation is a classical example where genetic testing does not help anything. Genetic testing cant help to make the diagnosis. In 20% of all LQTS patients it is not possible to find a mutation (false negative tests). In many cases the numbers are higher but it says more about the referring doctors than about the tests. You are in this group and it should not change your situation. If the clinical diagnosis is correct based on the ECGs and history, You have LQTS but none of these five genes Genaissance has investigated. These five genes covers most cases of identificable LQTS (>98%). There are at least three rare genes more involved and we test for two of them in Denmark (At some time in the future it would be all of them). Another problem with genetic testing is false positive answers. One out of ten healthy persons (one out of four of afro-american origin) has benign often rare variants of their LQTS genes which does not matter anything. If I understand the answer from genaissance correct, it is one of them they have found in you, and it seems that it does no matter, neither it is related to your ppossible LQTS. The conclusion is that if the diagnosis was correct before gene testing, its still correct after the answer from Genaissance. Your case shows the dangers of gene testing, it is quite common it does not help and it could even be dangerous in the hands of unexperienced electrophysiologist. However it should be mentioned that its very good in families where the diagnosis is established, since it could effectively find silent gene carriers in the family even when they have a appearing normal ECG. The problem is that it is used outside LQTS centers as a diagnostic tool, and this is it not intended to be. As seen on this website, the diagnostic criteria for LQTS does not include genetic testing | ||
| Jmac |
Dr Kanters: I don't have question just wanted to thank you for elaborating on that subject. It took me long time asking many questions to many doctors to fully understand the genetic role in LQTS. It took you only a few paragraphs to explain. It is very hard to know the questions you want to ask until you get the answers to some first. You did not leave much to ask and that is what makes this website so wonderful. Thank you for your time with all of us! Jmac | ||
| GMF |
Dr. Kanters: Thank you very much for your thorough & helpful response regarding genetic testing. Our genetic tests weren't a complete waste of time and money because they verified that no other immediate family members have my daughter's LQT3 gene. My daughter's EP recommended additional to genetic tests via skin (biopsy) instead of blood just to prove that mom and dad don't have LQT and my daughter is LQT3 first generation. Her doctor is currently consulting with LQT geneticists. We might delay further genetic testing for a several years until the EPs can clearly define & evaluate the results! Luckily, my EKG, electrocardiogram and stress tests all were normal. Now it's my wife's turn for additional testing beyond the EKG. Although my family has learned a lot during the last 5+ months of our LQT Adventure, there is still so much more for us to undestand about hearts, LQT3, AEDs, ICDs, genetic testing and etc! Thanks, Glenn | ||
| jmac |
Glenn, did they just test you and wife for LQT"3", no others forms? Just curious. Jmac (Judi) | ||
| GMF |
Judi: They did test for other genes as well as LQT3. I'm guessing that's how the class III variant was found in all of us? I'm going to be discussing the results further with my daughter's EP. Have you been tested? If so, did they find your LQT gene? Glenn | ||
| Jmac |
We did not go the commercial route. We have been in Dr. Art Moss research program with the University of Rochester, NY for almost 2 years now. No results. Research is very slow and until this years breakthrough with commercial testing, it was all we had. They are fairly sure it LQT2 by looks of ECG and triggers are startles, loud noises that all bothered me tremendously before beta blockers so I am fairly sure they are correct. I have also had "spells" upon wakening since betas so I really don't know what to think. Exercise has never been a problem. What is confusing is that my daughters symptoms seems to be aggravated by swimming or stair climbing which is not a problem with me. She was an avid swimmer but had many "spells" in junior high when trying competition swimming and she could not even get past warm up before faint symptoms would occur. Of course they never susupected heart back then, ECG was never done, just blood, EEG and brain scans and all neg. So it would seem that we have different triggers IF her symptoms were LQT related. That is why I really would like to find out the culprit so she could undergo testing and maybe then be persuaded to take betas. But as Dr. Kanters said, danger of testing is false positives and false negatives. It is soooo important to use the genetic test for what it is...identification only. Diagnosis should still be only from ECG. When no gene is found it gives people a false sense of security I suppose and that is what I see to be soooo dangerous. Jmac |