A novel deletion-frameshift mutation in the S1 region of HERG gene in a Chinese family with long QT syndrome

Background The congenital Long QT syndrome （LQTS） is a hereditary cardiac channelopathy that is characterized by a prolonged QT interval,syncope,ventricular arrhythmias,and sudden death.The chromosome 7-linked type 2 congenital LQTS （LQT2） is caused by gene mutations in the human ether-a-go-go-related gene （HERG）.Methods A Chinese family diagnosed with LQTS were screened for KCNQ1,HERG and SCN5A,using polymerase chain reaction （PCR）,direct sequencing,and clong sequencing.We also investigated the mRNA expression of the HERG gene.Results We identified a novel i414fs＋98X mutation in the HERG gene.The deletion mutation of 14-bp in the first transmembrane segment （S1） introduced premature termination codons （PTCs） at the end of exon 6.This mutation would result in a serious phenotype if the truncated proteins co-assembled with normal subunit to form the defective channels.But only the proband was symptomatic.Conclusions We found that the mRNA level of the HERG gene was significantly lower in 1414fs＋98X carriers than in noncarriers.We found a novel 1414fs＋98X mutation.The mRNA level supports that NMD mechanism might regulate the novel mutation.