A missense mutation (G604S) in the S5/pore region of HERG causes long QT syndrome in a Chinese family with a high incidence of sudden unexpected death.
Long QT syndrome (LQTS) is characterized by abnormalities in cardiac repolarization that lead to prolongation of the electrocardiographic (ECG) QT interval. Mutations in the human ether-a-go-go-related gene (HERG, KCNH2) cause the chromosome 7-linked LQT2 form of congenital LQTS, which is characterized by a prolonged QT interval and a bifid T-wave with an increased susceptibility to life-threatening cardiac arrhythmias, especially in children. We describe the genotypic and phenotypic pedigree of a large Chinese family (n = 36) in which 11 members were diagnosed with LQTS on the basis of typical ECG patterns for LQT2. Symptomatic syncopal episodes appeared in seven members of this family at a young age; an additional four members had died suddenly at ages of 18, 19, 24 and 70 years, respectively. Screening for SCN5A and HERG candidate genes identified a heterozygous missense mutation 1810G-->A in exon 7 of HERG that leads to the substitution of the amino acid glycine by serine (G604S); this mutation was located in the S5/pore region of the HERG protein and was associated with a malignant phenotype. Ten of the family members carrying the mutation showed a prolongation of the corrected QT interval (QTc), and seven of these had experienced multiple syncopal episodes. The retrospective examination of documented ECG records revealed that one family member who had died suddenly also had a prolonged QT interval. This study is the first to demonstrate a close correlation between clinical phenotype and genotype with a 100% penetrance based on the pedigree of a Chinese family with LQT2.
Zhang
Yanmin
Y
Department of Pediatrics, First Affiliated Hospital, Cardiovascular Ion Channel Disease Laboratory, Ministry of Education, Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China. zhangym@nail.xjtu.edu.cn
Zhou
Nan
N
Jiang
Wenhui
W
Peng
Jun
J
Wan
Hongmei
H
Huang
Chen
C
Xie
Zenghui
Z
Huang
Christopher L-H
CL
Grace
Andrew A
AA
Ma
Aiqun
A
D000293:Adolescent; D000328:Adult; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D016757:Death, Sudden, Cardiac / Q000209:etiology; D000072237:ERG1 Potassium Channel; D004562:Electrocardiography; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense / Q000235:genetics; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D013575:Syncope / Q000209:etiology / Q000235:genetics
D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human