The LTQ4 subtype of long QT syndrome is caused by a mutation in the genes which code for proteins cause ankyrins. People with this mutation experience sinus bradycardia, junctional escape rhythms, atrial fibrillation, and sudden death after physical or emotional stress. Ankyrins are important proteins that bind to various types of vital cell membrane channels which regulate the concentration of intracellular electrolytes. Abnormalities in the channels as a result of defective ankyrin proteins can lead to dangerous levels of intracellular calcium, and fatal arrhythmias.<unk>  is the only subtype of LQTS that does not involve sudden cardiac death as a part of another genetic disorder called Rett syndrome.
LQT4
LQT1
LQT2
LQT3
LQT5
LQT6
LQT10
LQT8