This is a pathology similar to LQTS, but it is caused by the calcium channel gene RYR2 or, less often, the sarcoplasmic reticulum protein calsequestrin 2 gene CASQ2. The mutation of the RYR2 gene destabilizes the calcium channel by causing leakage of a large amount of calcium, which hinders the sodium-calcium exchange that helps generate the cardiac potential needed for the heart to function 66. Here, RYR2 is linked to familial long QT syndrome.