MedGen

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. [from GeneReviews]

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. [from GeneReviews]

Congenital long QT syndrome is electrocardiographically characterized by a prolonged QT interval and polymorphic ventricular arrhythmias (torsade de pointes). These cardiac arrhythmias may result in recurrent syncope, seizure, or sudden death (Jongbloed et al., 1999). A form of torsade de pointes in which the first beat has a short coupling interval has been described (613600). Genetic Heterogeneity of Long QT Syndrome Other forms of LQT syndrome (LQTS) are LQT2 (613688), caused by mutation in the KCNH2 gene (152427); LQT3 (603830), caused by mutation in the SCN5A gene (600163); LQT4 (see 600919), caused by mutation in the ANK2 gene (106410); LQT5 (613695), caused by mutation in the KCNE1 gene (176261); LQT6 (613693), caused by mutation in the KCNE2 gene (603796); LQT7 (Andersen cardiodysrhythmic periodic paralysis, 170390), caused by mutation in the KCNJ2 gene (600681); LQT8 (618447), caused by mutation in the CACNA1C gene (114205); LQT9 (611818), caused by mutation in the CAV3 gene (601253); LQT10 (611819), caused by mutation in the SCN4B gene (608256); LQT11 (611820), caused by mutation in the AKAP9 gene (604001); LQT12 (612955), caused by mutation in the SNTA1 gene (601017); LQT13 (613485), caused by mutation in the KCNJ5 gene (600734); LQT14 (616247), caused by mutation in the CALM1 gene (114180), LQT15 (616249), caused by mutation in the CALM2 gene (114182); and LQT16 (618782), caused by mutation in the CALM3 gene (114183). Approximately 10% of LQTS patients in whom a mutation is identified in one ion channel gene carry a second mutation in the same gene or in another ion channel gene (Tester et al., 2005). Reviews Giudicessi and Ackerman (2016) reviewed the role of Ca(2+) cycling in cardiac repolarization and in the pathogenesis of long QT-associated cardiac arrhythmias. [from OMIM]

Increased time between the start of the Q wave and the end of the T wave as measured by the electrocardiogram (EKG). [from HPO]

Any abnormal alteration of atrioventricular conduction. [from SNOMEDCT_US]

Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both. [from HPO]

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. [from GeneReviews]