Table 2.

Cardiac Phenotype of Classic Timothy Syndrome

Cardiac PhenotypeAffected 1/Evaluated%Not Available
QTc prolongation25/251000
Functional 2:1 AV block17/21814
Congenital heart disease

TWA = T-wave alternance

PDA = patent ductus arteriosus

PFO = patent foramen ovale

VSD = ventricular septal defect

TOF = tetralogy of Fallot

HCM = hypertrophic cardiomyopathy


n = 25 (13 males, 12 females)

From: Timothy Syndrome

Cover of GeneReviews®
GeneReviews® [Internet].
Pagon RA, Adam MP, Ardinger HH, et al., editors.
Seattle (WA): University of Washington, Seattle; 1993-2017.
Copyright © 1993-2017, University of Washington, Seattle. GeneReviews is a registered trademark of the University of Washington, Seattle. All rights reserved.

GeneReviews® chapters are owned by the University of Washington. Permission is hereby granted to reproduce, distribute, and translate copies of content materials for noncommercial research purposes only, provided that (i) credit for source ( and copyright (© 1993-2017 University of Washington) are included with each copy; (ii) a link to the original material is provided whenever the material is published elsewhere on the Web; and (iii) reproducers, distributors, and/or translators comply with the GeneReviews® Copyright Notice and Usage Disclaimer. No further modifications are allowed. For clarity, excerpts of GeneReviews chapters for use in lab reports and clinic notes are a permitted use.

For more information, see the GeneReviews® Copyright Notice and Usage Disclaimer.

For questions regarding permissions or whether a specified use is allowed, contact: ude.wu@tssamda.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.