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(Circulation. 1999;99:1344-1347.)
© 1999 American Heart Association, Inc.

Clinical Investigation and Reports

Homozygous Deletion in KVLQT1 Associated With Jervell and Lange-Nielsen Syndrome

Qiuyun Chen, PhD; Danmei Zhang, MD; Robert L. Gingell, MD; Arthur J. Moss, MD; Carlo Napolitano, MD; Silvia G. Priori, MD, PhD; Peter J. Schwartz, MD; Eileen Kehoe, BS; Jennifer L. Robinson, MS; Eric Schulze-Bahr, MD; Qing Wang, PhD; Jeffrey A. Towbin, MD

From the Departmentx of Pediatrics (Cardiology) (Q.C., D.Z., Q.W., J.A.T.) and Molecular and Human Genetics (J.A.T.), Baylor College of Medicine, Texas Children's Hospital, Houston, Tex; Children's Hospital at Buffalo, Buffalo, NY (R.L.G.); Department of Medicine (A.J.M., E.K., J.L.R.,) and Department of Community and Preventive Medicine (J.L.R.), University of Rochester Medical Center, Rochester, NY; Department of Cardiology, University of Pavia, and Policlinico S. Matteo, IFCCS, Pavia, Italy (C.N., S.G.P., P.J.S.); and Hospital of the University of Munster, Munster, Germany (E.S.-B.).

Correspondence to Jeffrey A. Towbin, MD, Department of Pediatrics (Cardiology), Baylor College of Medicine, One Baylor Plaza, Room 333E, Houston, TX 77030. E-mail jtowbin{at}bcm.tmc.edu

Background—Long-QT (LQT) syndrome is a cardiac disorder that causes syncope, seizures, and sudden death from ventricular arrhythmias, specifically torsade de pointes. Both autosomal dominant LQT (Romano-Ward syndrome) and autosomal recessive LQT (Jervell and Lange-Nielsen syndrome, JLNS) have been reported. Heterozygous mutations in 3 potassium channel genes, KVLQT1, KCNE1 (minK), and HERG, and the cardiac sodium channel gene SCN5A cause autosomal dominant LQT. Autosomal recessive LQT, which is associated with deafness, has been found to occur with homozygous mutations in KVLQT1 and KCNE1 in JLNS families in which QTc prolongation was inherited as a dominant trait.

Methods and Results—An Amish family with clinical evidence of JLNS was analyzed for mutations by use of single-strand conformation polymorphism and DNA sequencing analyses for mutations in all known LQT genes. A novel homozygous 2-bp deletion in the S2 transmembrane segment of KVLQT1 was identified in affected members of this Amish family in which both QTc prolongation and deafness were inherited as recessive traits. This deletion represents a new JLNS-associated mutation in KVLQT1 and has deleterious effects on the KVLQT1 potassium channel, causing a frameshift and the truncation of the KVLQT1 protein. In contrast to previous reports in which LQT was inherited as a clear dominant trait, 2 parents in the JLNS family described here have normal QTc intervals (0.43 and 0.44 seconds, respectively).

Conclusions—A novel homozygous KVLQT1 mutation causes JLNS in an Amish family with deafness that is inherited as an autosomal recessive trait.

Key Words: long-QT syndrome • deafness • Jervell and Lange-Nielsen syndrome • potassium channel

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