KCND3 and type 2 diabetes mellitus: KCNQ1 encodes the pore-forming subunit of the voltage-gated K+ channel located not only in cardiac muscles but also in islet cells, the liver, and skeletal muscles; it is considered a susceptibility gene for type 2 diabetes (Finsterer and Stöllberger, 2004; Unoki et al., 2008; Yasuda et al., 2008; Yu et al., 2011).