LQT2 is one form of the congenital long QT syndrome. It results from mutati
ons in the human ether-a-go-go-related gene (HERG), and more than 80 mutati
ons, usually causing single amino acid substitutions in the HERG protein, a
re known, HERG encodes the ion channel pore-forming subunit protein for the
rapidly activating delayed rectifier K+ channel (I-Kr) in the heart. This
review summarizes current findings about mutations causing LQT2, the mechan
isms by which mutations may cause the clinical phenotype of a reduction in
I-Kr and a prolonged QT interval, and how this may be involved in the gener
ation of ventricular arrhythmias.