Although most of the LQTS mutant genes are related to K+ and Na+ channels (i.e. LQTS-1–3 being ~75–85% of total congenital LQTS), there are several Ca2+-signaling proteins that are linked to the occurrence of long QT intervals, typically causing LQTS-8, LQTS-14, LQTS-15, LQTS-16, and LQTS-17 (Table 1). Here, KLK7 is linked to familial long QT syndrome.