Table 1

Congenital long QT syndromes

	Gene^1-150	Current	Frequency	ECG	Circumstances surrounding events	DQT with exercise
LQT1	KvLQT1	↓I_Ks	40%	Broad T	Exercise, emotion	–
LQT2	HERG	↓I_Kr	40%	Bifid T	Sudden auditory stimuli	Normal
LQT3	SCN5A	↑I_Na	10%	Long isoelectric ST	Sleep	Supernormal
LQT4	Unknown		Rare
LQT5	minK	↓I_Ks	Rare
LQT6	MiRP1	↓I_Kr(?)	Rare
JLN1	KvLQT1	↓I_Ks	Rare	Marked ↑QT	Exertion
JLN2	minK	↓I_Ks	Rare	Marked ↑QT	Exertion

LQT1-6 are autosomal dominant without deafness (also termed Romano-Ward syndrome). JLN: Jervell-Lange-Neilsen syndrome (autosomal recessive with deafness) arises in individuals who inherit abnormal alleles from both parents, and is much rarer.
↵1-150 Some of these genes have alternate names. The “official” terms forKvLQT1, HERG,minK, and MiRP1are KCNQ1, KCNH2,KCNE1, and KCNE2, respectively. MinK is also known asIsK. HERG is an acronym for “Human Ether a-go-go-Related Gene”, andMiRP1 is an acronym for “MinK-Related Protein -1”.