Thursday, November 1, 2007
I have always had an issue with genetic testing in sudden cardiac death. A significant proportion of patients come up with "negative tests" Does that mean the patient and her/his family is not at genetic risk for sudden cardiac death? No....and now we do know there is another gene.
The gene is called GPD 1-L. Why is this gene important? Several reasons.
1. While not an ion channel (Which are the majority of Sudden Cardiac Death Genes) itself, it is a trafficking gene that allows the sodium channel to find its way to the cell membrane. Therefore the "channel" doesn't work properly. This has been known in LongQT syndrome and now Brugada Syndrome Many diseases have tricked us by these pathway variants, I can think of several modifier genes/polymorphisms in cystic fibrosis that can be missed on routine carrier screening
2. "we suspect that the function of the native GPD1-L gene and the mutant are influenced by oxidative stress, a process which interferes with the body's natural ability to repair itself from antioxidant assaults" Interestingly, smoking parents have been linked to SIDS deaths for quite some time now....This could lead to our finally understanding why on a given day someone who has this loaded gun can actually display the deadly arrythmia (funny heart beat)
3. This new discovery will help to identify those at risk of the >250,000 deaths each year from sudden cardiac death
The Sherpa Says: The evidence behind this link is solid. It is truly an identifiable cause of arrhythmia. Now if we could only get Familion to charge less than 5000 USD for this set of screening tests.....Perhaps we may be able to elucidate who will benefit from the device known as an Automated Inplantable Cardiac Defibrillator and who will not. Perhaps oxidative stress is the key linchpin here. Therefore, maybe by not smoking, taking antioxidants, avoiding oxidative stress we can prevent some of the 250k cases of arryhtmogenic death. Time will tell.