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Genetic footprinting in arrhythmias

Arrhythmias


In almost any disease there is a genetic component that contributes to the disease manifestation, and this genetic component is particularly strong in inherited arrhythmias.

Silvia Priori from Pavia, Italy started the session by providing a brief update of the mutations in ion channels that are known to be causal in Long QT Syndrome and sudden cardiac death (SCD). Taking the cardiac sodium channel (SCN5A) as an example, mutations in the SCN5A gene can lead to multiple rhythm disturbances through a variety of defects in the different biophysical channel properties. The overlap in QTc interval distribution in populations of mutation carriers vs. non carriers is substantial, indicating that gene penetrance varies and is modified by additional factors. Polymorphisms in genes encoding for ion channels increase the susceptibility of developing an arrhythmia. Genome-wide association studies have identified single nucleotides polymorphisms that may serve as markers for the susceptibility of atrial fibrillation, SCD and LQTS.

Christian Wolpert from Mannheim, Germany asked how SCD could be prevented by genetic risk calculations and proposed a score indicating whether or not genotyping has an impact on diagnosis or treatment with a low score for Short QT syndrome (due to small patient numbers) and a high score in LQT syndrome for members of an affected family.

Raymondo Brugada, Girona, Spain was sceptical of whether genetic information will provide the basis for clinical decision making, because a certain mutation may behave very differently in other families. The great variability in phenotype is determined by other factors such as environment or triggers.

The last speaker, Arthur Wilde from Amsterdam, Netherlands also detailed the costs of genetic screening and provided some cost benefit relationship. Family members of a symptomatic LQTS patient can receive commercial genotyping, however, many of the detected polymorphisms may not be of any predictive value.

In conclusion, although genotyping has made a big contribution to the management of patients with LQTS and CPVT, it is not the whole story. To answer the problems of genotype/phenotype mismatch more has to learned with respect to the impact of gene polymorphisms in modifying the susceptibility to arrhythmic phenotype.

References


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SessionTitle:

Genetic footprinting in arrhythmias

Notes to editor


This congress report accompanies a presentation given at the ESC Congress 2009. Written by the author himself/herself, this report does not necessarily reflect the opinion of the European Society of Cardiology.

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.