title: The phenotype characteristics of type 13 long QT syndrome with mutation in KCNJ5 (Kir3.4-G387R).
abstract: BACKGROUND
  Long QT syndrome type 13 (LQT13) is caused by loss-of-function mutation in the KCNJ5-encoded cardiac G-protein-coupled inward rectifier potassium channel subtype 4 protein. The electrocardiographic (ECG) features of LQT13 are not described yet.
  
  
  OBJECTIVE
  To describe for the first time in detail the phenotype-genotype relationship of the ECG and clinical features in patients with LQT13.
  
  
  METHODS
  The 12-lead ECGs, 24-hour Holter recordings, and clinical information from KCNJ5-G387R mutation carriers of a fourth-generation Han Chinese family with LQT13 and a group of healthy Chinese individuals were analyzed.
  
  
  RESULTS
  Compared with the analysis of the healthy group (n = 8), age- and sex-matched pair analysis revealed that the mutation carriers (n = 8) had ventricular repolarization abnormality results in the prolongation of corrected QT and QTpeak intervals (P < .01); greater combined measure of repolarization morphology (T-wave morphology combination score) based on asymmetry, flatness, and notch (P < .01); and reduced low frequency/high frequency ratio of heart rate variability (P < .01) as a reflection of cardiac autonomic imbalance. Mean heart rate, time domain parameters of heart rate variability, time interval from T-wave peak to T-wave end, and T-wave amplitude were similar.
  
  
  CONCLUSIONS
  This study demonstrates for the first time the ECG features of patients with LQT13. Our data suggest that QTpeak intervals and T-wave morphology combination score may be the better parameters than the corrected QT interval to predict the phenotype-genotype relationship in patients with LQT13.
authors.affiliation: Laboratory of Experimental Cardiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.forename: Jinqiu
authors.initials: J
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Hong
authors.forename: Bo
authors.initials: B
authors.lastname: Liang
authors.forename: Claus
authors.initials: C
authors.lastname: Graff
authors.forename: Yanzong
authors.initials: Y
authors.lastname: Yang
authors.forename: Michael
authors.initials: M
authors.lastname: Christiansen
authors.forename: Søren-Peter
authors.initials: SP
authors.lastname: Olesen
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Jørgen K
authors.initials: JK
authors.lastname: Kanters
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics*; D005838:Genotype; D006339:Heart Rate / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D008133:Long QT Syndrome / Q000235:genetics* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C484274:KCNJ5 protein, human
keywords: AAI; AF; APD; AVB; ECG; G-protein coupled inward rectifier potassium channel subtype 4 protein; GIRK4; HRV; Heart rate variability; I(K,ACh)(I(GIRK)); Kir3.4 (GIRK4); LF/HF; LQT13; LQTS; MCS; Morphology combination score; QT; QTc; QTcF; RMP; T-wave morphology; T-wave morphology combination score; TpTe; VVI; acetylcholine/adenosine-induced potassium current; action potential duration; atrial fibrillation; atrioventricular block; atrium paced, atrium sensed, and pacemaker inhibited in response to sensed beat; corrected QT interval; corrected QT interval for heart rate using the formula QTcF = QT/RR(1/3); electrocardiogram/electrocardiographic; heart rate variability; long QT syndrome; long QT syndrome type 13; low frequency/high frequency ratio; resting membrane potential; time interval from T-wave peak to T-wave end; ventricle paced, ventricle sensed, and pacemaker inhibited in response to sensed beat