hERG potassium channels are essential for normal electrical activity in the heart. Inherited mutations in the HERG gene cause long QT syndrome, a disorder that predisposes individuals to life-threatening arrhythmias. Arrhythmia can also be induced by a blockage of hERG channels by a surprisingly diverse group of drugs. This side effect is a common reason for drug failure in preclinical safety trials. Insights gained from the crystal structures of other potassium channels have helped our understanding of the block of hERG channels and the mechanisms of gating.

hERG potassium channels and cardiac arrhythmia

Inwardly rectifying K+ (Kir) channels allow K+ to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are ...

Inwardly Rectifying Potassium Channels: Their Structure, Function, and Physiological Roles

http://www.cardiologia-vigo.com/wp-content/uploads/2011/10/2011_HRS-EHRA_GeneticTesting.pdf

HRS/EHRA Expert Consensus Statement on the State of Genetic Testing for the Channelopathies and Cardiomyopathies: This document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA)

This international consensus statement provides the state of genetic testing for the channelopathies and cardiomyopathies. It summarizes the opinion of the international writing group members based on their own experience and on a general review of the literature with respect to the use and role of genetic testing for these potentially heritable cardiac conditions. This document focuses primarily on the state of genetic testing for the 13 distinct entities detailed and the relative diagnostic, prognostic, and therapeutic impact of the genetic test result for each entity. It does not focus on the therapeutic management of the various channelopathies and cardiomyopathies. Treatment/management issues are only discussed for those diseases (i.e., LQTS, HCM, DCM + CCD, RCM) in which the genetic test result could potentially influence treatment considerations.

Writing recommendations for genetic diseases require adaptation of the methodology normally adopted to prepare guidelines for clinical practice. Documents produced by other scientific societies have acknowledged the need to define the criteria used to rank the strength of recommendation for genetic diseases.1

The most obvious difference is that randomized and/or blinded studies do not exist. Instead, most of the available data are derived from registries that have followed patients and recorded outcome information. The authors of this statement have therefore defined specific criteria for Class I, Class IIa or b, and Class III recommendations and have used the conventional language adopted by AHA/ACC/ESC Guidelines to express each class. All recommendations are level of evidence (LOE) C (i.e., based on experts' opinions).

A Class I recommendation ( “is recommended” ) was applied for genetic testing in index cases with a sound clinical suspicion for the presence of a channelopathy or a cardiomyopathy when the positive predictive value of a genetic test is high (likelihood of positive result >40% and signal/noise ratio >10; Table 3), AND/OR when …

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HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies

MicroRNAs (miRNAs) are a class of posttranscriptional regulators that have recently introduced an additional level of intricacy to our understanding of gene regulation. There are currently over 10,000 miRNAs that have been identified in a range of species including metazoa, mycetozoa, viridiplantae, and viruses, of which 940, to date, are found in humans. It is estimated that more than 60% of human protein-coding genes harbor miRNA target sites in their 3′ untranslated region and, thus, are potentially regulated by these molecules in health and disease. This review will first briefly describe the discovery, structure, and mode of function of miRNAs in mammalian cells, before elaborating on their roles and significance during development and pathogenesis in the various mammalian organs, while attempting to reconcile their functions with our existing knowledge of their targets. Finally, we will summarize some of the advances made in utilizing miRNAs in therapeutics.

/pdf/micrornas-in-development-and-disease-472gt45lvo.pdf

John Wesley Clark

Papers

Mutations in Kir2.1 cause the developmental and episodic electrical phenotypes of Andersen's syndrome