QT interval is linked to 2 long-QT syndrome loci in normal subjects.
BACKGROUND
The rate-corrected QT interval (QTc) is heritable, and the discovery of quantitative trait loci that influence the QTc would be an important step in identifying the genes responsible for life-threatening arrhythmias in the general population. We studied 66 pairs of unselected normal dizygotic (DZ) twin subjects and their parents in a sib-pair analysis. We tested for linkage of gene loci harboring genes known to cause the long-QT syndrome (LQT) to the quantitative trait QTc.


RESULTS
We found genetic variance on QRS duration, QRS axis, T-wave axis, and QTc. Women had a longer QTc than men. Microsatellite markers were tested in the vicinity of the gene loci for the 5 known LQT genes. We found significant linkage of QTc with the loci for LQT1 on chromosome 11 and LQT4 on chromosome 4 but not to LQT2, LQT3, or LQT5. We also found linkage of the QRS axis with LQT2 and LQT3.


CONCLUSIONS
We suggest that these quantitative trait loci may represent the presence of variations in LQT genes that could be important to the risk for rhythm disturbances in the general population.
Busjahn
A
A
Franz Volhard Clinic and Max Delbrück Center for Molecular Medicine, Medical Faculty of the Charité, Humboldt University of Berlin, Germany.
Knoblauch
H
H
Faulhaber
H D
HD
Boeckel
T
T
Rosenthal
M
M
Uhlmann
R
R
Hoehe
M
M
Schuster
H
H
Luft
F C
FC
D000328:Adult; D000483:Alleles; D002880:Chromosomes, Human, Pair 11; D002894:Chromosomes, Human, Pair 4; D004276:DNA, Satellite / Q000032:analysis; D004562:Electrocardiography; D005260:Female; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
D004276:DNA, Satellite; D005819:Genetic Markers