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Long QT syndrome 14(LQT14)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonym: LQT14
Gene (location): CALM1 (14q32.11)
Monarch Initiative: MONDO:0014548
OMIM®: 616247

Alexander J Groffen  |  Hennie Bikker  |  Imke Christiaans   view full author information

Additional descriptions

From GeneReviews Overview
Long QT syndrome (LQTS) is a cardiac electrophysiologic disorder, characterized by QT prolongation and T-wave abnormalities on the EKG that are associated with tachyarrhythmias, typically the ventricular tachycardia torsade de pointes (TdP). TdP is usually self-terminating, thus causing a syncopal event, the most common symptom in individuals with LQTS. Such cardiac events typically occur during exercise and emotional stress, less frequently during sleep, and usually without warning. In some instances, TdP degenerates to ventricular fibrillation and causes aborted cardiac arrest (if the individual is defibrillated) or sudden death. Approximately 50% of untreated individuals with a pathogenic variant in one of the genes associated with LQTS have symptoms, usually one to a few syncopal events. While cardiac events may occur from infancy through middle age, they are most common from the preteen years through the 20s. Some types of LQTS are associated with a phenotype extending beyond cardiac arrhythmia. In addition to the prolonged QT interval, associations include muscle weakness and facial dysmorphism in Andersen-Tawil syndrome (LQTS type 7); hand/foot, facial, and neurodevelopmental features in Timothy syndrome (LQTS type 8); and profound sensorineural hearing loss in Jervell and Lange-Nielson syndrome.
LQT14 is a cardiac arrhythmia disorder characterized by ventricular arrhythmias, often life-threatening, occurring very early in life, frequent episodes of T-wave alternans, markedly prolonged QTc intervals, and intermittent 2:1 atrioventricular block (Crotti et al., 2013). Patients with LQT14, LQT15 (616249), or LQT16 (618782), resulting from mutation in calmodulin genes CALM1, CALM2 (114182), or CALM3 (114183), respectively, typically have a more severe phenotype, with earlier onset, profound QT prolongation, and a high predilection for cardiac arrest and sudden death, than patients with mutations in other genes (Boczek et al., 2016).  http://www.omim.org/entry/616247

Clinical features

From HPO
Sudden death
MedGen UID:
Concept ID:
Pathologic Function
Rapid and unexpected death.
Cardiac arrest
MedGen UID:
Concept ID:
An abrupt loss of heart function.
Ventricular fibrillation
MedGen UID:
Concept ID:
Disease or Syndrome
Uncontrolled contractions of muscles fibers in the left ventricle not producing contraction of the left ventricle. Ventricular fibrillation usually begins with a ventricular premature contraction and a short run of rapid ventricular tachycardia degenerating into uncoordinating ventricular fibrillations.
Prolonged QT interval
MedGen UID:
Concept ID:
Increased time between the start of the Q wave and the end of the T wave as measured by the electrocardiogram (EKG).
Prolonged QTc interval
MedGen UID:
Concept ID:
Pathologic Function
A longer than normal interval (corrected for heart rate) between the Q and T waves in the heart's cycle. Prolonged QTc can cause premature action potentials during late phase depolarizations thereby leading to ventricular arrhythmias and ventricular fibrillations.
T-wave alternans
MedGen UID:
Concept ID:
A periodic beat-to-beat variation in the amplitude or shape of the T wave in an EKG.
2:1 atrioventricular block
MedGen UID:
Concept ID:
Disease or Syndrome
A type of second-degree atrioventricular block in which every other P wave is not conducted through the AV node such that only every other P wave is followed by a QRS complex.

Term Hierarchy

Professional guidelines


Kaufman ES, Eckhardt LL, Ackerman MJ, Aziz PF, Behr ER, Cerrone M, Chung MK, Cutler MJ, Etheridge SP, Krahn AD, Lubitz SA, Perez MV, Priori SG, Roberts JD, Roden DM, Schulze-Bahr E, Schwartz PJ, Shimizu W, Shoemaker MB, Sy RW, Towbin JA, Viskin S, A M Wilde A, Zareba W
Circ Arrhythm Electrophysiol 2021 Jul;14(7):e009726. Epub 2021 Jul 9 doi: 10.1161/CIRCEP.120.009726. PMID: 34238011Free PMC Article
Michaud V, Dow P, Al Rihani SB, Deodhar M, Arwood M, Cicali B, Turgeon J
Clin Transl Sci 2021 Jan;14(1):20-28. Epub 2020 Nov 18 doi: 10.1111/cts.12882. PMID: 32888379Free PMC Article
Markiewicz-Łoskot G, Moric-Janiszewska E, Mazurek U
Ann Noninvasive Electrocardiol 2009 Jan;14(1):86-92. doi: 10.1111/j.1542-474X.2008.00278.x. PMID: 19149798Free PMC Article

Recent clinical studies


Sun Q, Xie Z, Wang F, Guo J, Yan X
Mol Genet Genomic Med 2024 Jan;12(1):e2287. Epub 2023 Oct 31 doi: 10.1002/mgg3.2287. PMID: 37905352Free PMC Article


Sun Q, Xie Z, Wang F, Guo J, Yan X
Mol Genet Genomic Med 2024 Jan;12(1):e2287. Epub 2023 Oct 31 doi: 10.1002/mgg3.2287. PMID: 37905352Free PMC Article

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