A novel mutation - L539fs/47 of hERG in a Chinese long QT syndrome family / 西安交通大学学报·英文版

Objective: To identify the mutation of human ether-a-go-go-related gene (hERG) and analyze the clinical characteristics of a Chinese family with long ST syndrome (LQTS). Methods: The electrocardiogram and DNA samples were obtained from a Chinese LQTS family of 26 members. Genotype was performed with polymorphic short tandem repeat (STR) markers at the known LQT1, LQT2, and LQT3 loci. SSCP analysis was used to find aberrant conformers. hERG mutation was confirmed by cloning and sequencing. Results: Three gene carriers were linked to chromosome 7q35-36, where the potassium channel gene hERG was encoded. A 19-base pair deletion was identified. The mutation was located at nucleotide position 1619-1637 between transmembrane domains S4 and S5. Furthermore, A1692G polymorphism was found both in the normal control and patients. Conclusion: A novel 19 bp deletion mutation of hERG is identified in a Chinese family. All gene carriers are demonstrated to be typical LQT2 ECG phenotype.

Functional expression of congenital long QT syndrome related HERG mutation A561V in vitro / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the functional expression of HERG mutation A561V detected in a Chinese congenital long QT syndrome family.</p><p><b>METHODS</b>The mutation gene A561V was cloned into eukaryotic expressive vector pcDNA3 by quick site-directed mutagenesis PCR and restriction enzymes. The wild-type HERG, heterozygous type HERG and HERG mutation A561V were respectively cotransfected with pRK5-GFP into HEK293 cells by Suprefact transfection regent. The protein expression was measured by immunofluorescence method and Western blot. The electrophysiological characteristics of transfected cells were determined by whole cell patch-clamp technique.</p><p><b>RESULTS</b>Direct sequence analyses revealed a C to T transition at position 1682. A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein expression of mutation and heterozygosis were located in cytoplasm and cellular membrane. 155 kDa and 135 kDa protein bands were detected in wild type HERG channel while only 135 kDa protein band was shown in heterozygous and mutational channels. Significant HERG tail-current was recorded in wild type HERG channel but not in mutation and heterozygosis channels.</p><p><b>CONCLUSION</b>This study evidenced a functional dominant-negative current suppression in HEK293 cells transfected with HERG mutation A561V.</p>

Construction of eukaryotic expression vector of congenital long QT syndrome related HERG gene A561V mutation and its expression in HEK293 cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the protocol of the construction of HERG gene mutations, an A561V mutation which was detected in a Chinese congenital long QT syndrome (LQTS) family had been constructed and expressed in vitro.</p><p><b>METHODS</b>The A561V cloning vector PGEM-HERG-A561V was constructed by quick site-directed mutagenesis PCR. The A561V expressive vector pcDNA3-HERG-A561V was constructed by restriction enzymes. pRK5-GFP was cotransfected with pcDNA3-HERG-A561V or wild type pcDNA3-HERG into HEK293 cells by Superfect transfection reagent. The protein was measured by immunofluorescence.</p><p><b>RESULTS</b>Direct sequence analyses revealed a C to T transition at position 1682. The A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein of mutation was expressed in cytoplasm and cellular membrane while the wild type gene was expressed only on cellular membrane.</p><p><b>CONCLUSION</b>The protocol can be used successfully to construct and express HERG A561V mutation and it forms the basement of the further study on functions of mutation.</p>

Single nucleotide polymorphisms of genes associated with high density lipoprotein metabolism in Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the single nucleotide polymorphisms in genes associated with the high density lipoprotein (HDL) metabolism in Chinese population.</p><p><b>METHODS</b>Two hundred and nine normal Han ethnic subjects, aged 59+/-10 years, were recruited from 5 medical centers in western part of China. DNA was extracted by proteinase K digestion, phenol and chloroform extraction as well as isopropanol precipitation. The polymerase chain reaction (PCR)-restriction fragment length polymorphisms (RFLP) in conjunction with sequencing were employed to test the single nucleotide polymorphisms (SNPs) in ATP-binding cassette transporter (ABCA1), cholesteryl ester transfer protein (CETP) and lipoprotein lipase (LPL) genes.</p><p><b>RESULTS</b>The allelic frequencies of A and G of ABCA1 gene are 53.4% and 46.6%; of B2 and B1 allele of CETP, 41.0% and 59.0%; of HindIII (-) and (+) allele of LPL, 18.9% and 81.1%; and of PvuII(+) and (-) allele of LPL, 66.0% and 34.0%, respectively. All genotype frequencies fit well with the Hardy-Weinberg equilibrium; the significant linkage disequilibrium exists between LPL HindIII(+)and PvuII(+) polymorphisms. All of the RFLP in these genes result from the single nucleic substitution in fragment recognized by corresponding restriction enzymes.</p><p><b>CONCLUSION</b>The genetic polymorphisms of ABCA1, LPL-HindIII and LPL-PvuII in Chinese Han ethnic population are significantly different from Caucasians residing in USA or Europe.</p>

Long QT syndrome gene diagnosis by haplotype analysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Three long QT syndrome(LQTS) pedigrees were brought together for genetic diagnosis by using short tandem repeat(STR) markers.</p><p><b>METHODS</b>Genomic DNA was extracted from blood samples. STR markers (D7S1824, D7S2439, D7S483, D3S1298, D3S1767, D3S3521) in or spanning the HERG and SCN5A gene were amplified; the haplotype analysis for LQTS was performed.</p><p><b>RESULTS</b>Clinical diagnosis showed that 15 are LQTS patients (3 died) and 11 are probable patients. Linkage analysis showed that LQTS patients are linked with the SCN5A gene in family 1, HERG is linked with the disease in family 2 and 3. Fourteen gene carriers were identified, 2 patients and 7 probable patients were excluded.</p><p><b>CONCLUSION</b>Linkage analysis using STR markers can serve as useful tool for presymptomatic diagnosis.</p>