[Genetic bases of arrhythmias].

We have long known that there are diseases which are inherited from the parents, but it has not been until this last decade, with the introduction of the techniques of molecular biology, that we have been able to study them. These techniques have enable us to localize and detect the gene that causes a disease in the members of a family. The identification of a disease-causing gene does not lead only to the diagnosis and possible treatment of a very select patient population (the one with the familial disease), but also to a better understanding of the molecular basis and pathogenesis of the non-familial forms of the disease. Cardiology, despite having received these techniques more slowly, is now completely. Involved in the study of the molecular basis of cardiac diseases. The first gene to be mapped was that of hypertrophic cardiomyopathy in 1989. Since then, advances have been achieved at all levels in familial cardiac diseases. Hypertension, atherosclerosis, congenital heart diseases, and arrhythmias have all benefitted from the new techniques. Spectacular progress has been achieved in understanding familial heart rhythm disturbances, like long QT syndrome, both as congenital and acquired diseases. In the last five years 4 loci and 3 genes have been identified. The first studies of genetic based therapy have shown that in the near future patients with receive medication depending on the affected gene. Other familial arrhythmias are presently under study. Loci have been detected in some, such as bundle branch block and familial atrial fibrillation. At the speed that the techniques are evolving, and with the impressive advances of the Human Genome Project, we can expect to find the rest of the genes causing familial diseases in the next few years. These results are encouraging and clearly indicate the need for genetic diagnosis in all patients with these diseases. The diagnostic and therapeutic implications of all these discoveries could be of paramount importance.