RESUMEN
Toll-like receptors (TLRs) play key roles in innate immune recognition of pathogen-associated molecular patterns of invading microbes. Among the 10 TLR family members identified in humans, TLR10 remains an orphan receptor without known agonist or function. TLR10 is a pseudogene in mice and mouse models are noninformative in this regard. Using influenza virus infection in primary human peripheral blood monocyte-derived macrophages and a human monocytic cell line, we now provide previously unidentified evidence that TLR10 plays a role in innate immune responses following viral infection. Influenza virus infection increased TLR10 expression and TLR10 contributed to innate immune sensing of viral infection leading to cytokine induction, including proinflammatory cytokines and interferons. TLR10 induction is more pronounced following infection with highly pathogenic avian influenza H5N1 virus compared with a low pathogenic H1N1 virus. Induction of TLR10 by virus infection requires active virus replication and de novo protein synthesis. Culture supernatants of virus-infected cells modestly up-regulate TLR10 expression in nonvirus-infected cells. Signaling via TLR10 was activated by the functional RNA-protein complex of influenza virus leading to robust induction of cytokine expression. Taken together, our findings identify TLR10 as an important innate immune sensor of viral infection and its role in innate immune defense and immunopathology following viral and bacterial pathogens deserves attention.
Asunto(s)
Inmunidad Innata/inmunología , Subtipo H5N1 del Virus de la Influenza A/inmunología , Gripe Humana/inmunología , Receptor Toll-Like 10/inmunología , Animales , Benzotiazoles , Western Blotting , Cartilla de ADN/genética , Diaminas , Perros , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente , Humanos , Subtipo H1N1 del Virus de la Influenza A/inmunología , Macrófagos , Células de Riñón Canino Madin Darby , Ratones , Compuestos Orgánicos , Quinolinas , ARN Interferente Pequeño/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Receptor Toll-Like 10/metabolismoRESUMEN
The negative impact of extreme temperatures on health is well-established. Individual help-seeking behavior, however, may mitigate the extent of morbidity and mortality during elevated temperatures. This study examines individual help-seeking behavior during periods of elevated temperatures among a Chinese population. Help-seeking patterns and factors that influence behavior will be identified so that vulnerable subgroups may be targeted for health protection during heat crises. A retrospective time-series Poisson generalized additive model analysis, using meteorological data of Hong Kong Observatory and routine emergency help call data from The Hong Kong Senior Citizen Home Safety Association during warm seasons (June-September) 1998-2007, was conducted. A "U"-shaped association was found between daily emergency calls and daily temperature. About 49% of calls were for explicit health-related reasons including dizziness, shortness of breath, and general pain. The associate with maximum temperature was statistically significant (p = 0.034) with the threshold temperature at which the frequency of health-related calls started to increase being around 30-32°C. Mean daily relative humidity (RH) also had a significant U-shaped association with daily emergency health-related calls with call frequency beginning to increase with RH greater than 70-74% (10-25% of the RH distribution). Call frequency among females appeared to be more sensitive to high temperatures, with a threshold between 28.5°C and 30.5°C while calls among males were more sensitive to cold temperatures (threshold 31.5-33.5°C). Results indicate differences in community help-seeking behavior at elevated temperatures. Potential programs or community outreach services might be developed to protect vulnerable subgroups from the adverse impact of elevated temperatures.
Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Comportamiento del Consumidor/estadística & datos numéricos , Calor/efectos adversos , Población Urbana/estadística & datos numéricos , Adaptación Psicológica , Anciano , Cambio Climático , Femenino , Conocimientos, Actitudes y Práctica en Salud , Necesidades y Demandas de Servicios de Salud , Hong Kong/etnología , Humanos , Masculino , Modelos Psicológicos , Modelos Estadísticos , Distribución de Poisson , Estudios Retrospectivos , Estudios de Tiempo y MovimientoAsunto(s)
Inhibidores de la Ciclooxigenasa/farmacología , Subtipo H5N1 del Virus de la Influenza A/efectos de los fármacos , Gripe Aviar/tratamiento farmacológico , Gripe Humana/tratamiento farmacológico , Nitrobencenos/farmacología , Sulfonamidas/farmacología , Animales , Aves , Técnicas de Cultivo de Célula , Inhibidores de la Ciclooxigenasa/uso terapéutico , Humanos , Macrófagos , Nitrobencenos/uso terapéutico , Alveolos Pulmonares/citología , Sulfonamidas/uso terapéutico , Replicación Viral/efectos de los fármacosRESUMEN
A selective cyclooxygenase-2 (COX-2) inhibitor has been previously shown to suppress the hyper-induced pro-inflammatory responses in H5N1 infected primary human cells. Here, we demonstrate that COX-2 inhibitors suppress H5N1 virus replication in human macrophages suggesting that H5N1 virus replication (more so than seasonal H1N1 virus) is dependent on activation of COX-2 dependent signaling pathways in host cells. COX-2 and its downstream signaling pathways deserve detailed investigation as a novel therapeutic target for treatment of H5N1 disease.
Asunto(s)
Ciclooxigenasa 2/metabolismo , Subtipo H5N1 del Virus de la Influenza A/efectos de los fármacos , Gripe Humana/tratamiento farmacológico , Macrófagos/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Sulfonamidas/farmacología , Proteínas Virales/metabolismo , Animales , Antivirales/farmacología , Aves , Células Cultivadas , Ciclooxigenasa 2/genética , Inhibidores de la Ciclooxigenasa 2/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/fisiología , Subtipo H5N1 del Virus de la Influenza A/fisiología , Gripe Aviar/tratamiento farmacológico , Gripe Aviar/virología , Gripe Humana/virología , Macrófagos/citología , Macrófagos/virología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Proteínas Virales/genética , Replicación Viral/efectos de los fármacosRESUMEN
BACKGROUND: Pandemic influenza H1N1 (pdmH1N1) virus causes mild disease in humans but occasionally leads to severe complications and even death, especially in those who are pregnant or have underlying disease. Cytokine responses induced by pdmH1N1 viruses in vitro are comparable to other seasonal influenza viruses suggesting the cytokine dysregulation as seen in H5N1 infection is not a feature of the pdmH1N1 virus. However a comprehensive gene expression profile of pdmH1N1 in relevant primary human cells in vitro has not been reported. Type I alveolar epithelial cells are a key target cell in pdmH1N1 pneumonia. METHODS: We carried out a comprehensive gene expression profiling using the Affymetrix microarray platform to compare the transcriptomes of primary human alveolar type I-like alveolar epithelial cells infected with pdmH1N1 or seasonal H1N1 virus. RESULTS: Overall, we found that most of the genes that induced by the pdmH1N1 were similarly regulated in response to seasonal H1N1 infection with respect to both trend and extent of gene expression. These commonly responsive genes were largely related to the interferon (IFN) response. Expression of the type III IFN IL29 was more prominent than the type I IFN IFNß and a similar pattern of expression of both IFN genes was seen in pdmH1N1 and seasonal H1N1 infection. Genes that were significantly down-regulated in response to seasonal H1N1 but not in response to pdmH1N1 included the zinc finger proteins and small nucleolar RNAs. Gene Ontology (GO) and pathway over-representation analysis suggested that these genes were associated with DNA binding and transcription/translation related functions. CONCLUSIONS: Both seasonal H1N1 and pdmH1N1 trigger similar host responses including IFN-based antiviral responses and cytokine responses. Unlike the avian H5N1 virus, pdmH1N1 virus does not have an intrinsic capacity for cytokine dysregulation. The differences between pdmH1N1 and seasonal H1N1 viruses lay in the ability of seasonal H1N1 virus to down regulate zinc finger proteins and small nucleolar RNAs, which are possible viral transcriptional suppressors and eukaryotic translation initiation factors respectively. These differences may be biologically relevant and may represent better adaptation of seasonal H1N1 influenza virus to the host.
Asunto(s)
Citocinas/inmunología , Huésped Inmunocomprometido/inmunología , Subtipo H1N1 del Virus de la Influenza A/fisiología , Gripe Humana/inmunología , Alveolos Pulmonares/inmunología , Alveolos Pulmonares/virología , Estaciones del Año , Línea Celular , Células Epiteliales/inmunología , Células Epiteliales/virología , Humanos , PandemiasRESUMEN
The recent emergence of a novel H1N1 influenza A virus in humans caused the first influenza pandemic of this century. Many clinical diagnostic laboratories are overwhelmed by the testing demands related to the infection. Three novel H1N1-specific primer-probe sets reported during the early phase of the pandemic were tested in three commercial real-time RT-PCR mixtures. The amplification efficiencies and detection limits of these assays were determined. A ready-to-use premixed RT-PCR stored in a lyophilized format was developed. The detection limits of the studied assays were highly variable, ranging from 1.68E-01 to 1.68E-05 TCID(50) per reaction. The detection limit of the lyophilized reaction mixture was found to be 1.68E-05 TCID(50) per reaction, but the amplification efficiency of the assay was lower than those deduced from the other assays. All respiratory samples from infected patients and all control nasopharyngeal aspirates were positive and negative, respectively, in the newly developed assay. The results highlighted that, to enhance the sensitivity of an assay, it is essential to evaluate a primer-probe set with different commercial RT-PCR assays. This study also demonstrated the feasibility of using lyophilized reaction mixtures for the molecular diagnosis of novel H1N1.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/diagnóstico , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Cartilla de ADN , Liofilización , Humanos , Juego de Reactivos para DiagnósticoRESUMEN
Human disease caused by highly pathogenic avian influenza (HPAI) H5N1 can lead to a rapidly progressive viral pneumonia leading to acute respiratory distress syndrome. There is increasing evidence from clinical, animal models and in vitro data, which suggests a role for virus-induced cytokine dysregulation in contributing to the pathogenesis of human H5N1 disease. The key target cells for the virus in the lung are the alveolar epithelium and alveolar macrophages, and we have shown that, compared to seasonal human influenza viruses, equivalent infecting doses of H5N1 viruses markedly up-regulate pro-inflammatory cytokines in both primary cell types in vitro. Whether this H5N1-induced dysregulation of host responses is driven by qualitative (i.e activation of unique host pathways in response to H5N1) or quantitative differences between seasonal influenza viruses is unclear. Here we used microarrays to analyze and compare the gene expression profiles in primary human macrophages at 1, 3, and 6 h after infection with H5N1 virus or low-pathogenic seasonal influenza A (H1N1) virus. We found that host responses to both viruses are qualitatively similar with the activation of nearly identical biological processes and pathways. However, in comparison to seasonal H1N1 virus, H5N1 infection elicits a quantitatively stronger host inflammatory response including type I interferon (IFN) and tumor necrosis factor (TNF)-alpha genes. A network-based analysis suggests that the synergy between IFN-beta and TNF-alpha results in an enhanced and sustained IFN and pro-inflammatory cytokine response at the early stage of viral infection that may contribute to the viral pathogenesis and this is of relevance to the design of novel therapeutic strategies for H5N1 induced respiratory disease.
Asunto(s)
Interacciones Huésped-Patógeno/inmunología , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H5N1 del Virus de la Influenza A/inmunología , Gripe Aviar/virología , Gripe Humana/virología , Macrófagos/inmunología , Macrófagos/virología , Animales , Aves/virología , Células Cultivadas , Regulación hacia Abajo/genética , Perfilación de la Expresión Génica , Interacciones Huésped-Patógeno/genética , Humanos , Gripe Aviar/inmunología , Gripe Humana/inmunología , Interferón Tipo I/inmunología , Monocitos/citología , Análisis de Secuencia por Matrices de Oligonucleótidos , Reproducibilidad de los Resultados , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Factores de Tiempo , Regulación hacia Arriba/genéticaRESUMEN
The initiation of transcription and replication of influenza A virus requires the 5' and 3' ends of vRNA. Here, the role of segment-specific non-coding sequences of influenza A virus on viral RNA synthesis was studied. Recombinant viruses, with the nonstructural protein (NS) segment-specific non-coding sequences replaced by the corresponding sequences of the neuraminidase (NA) segment, were characterized. The NS and NA vRNA levels in cells infected with these mutants were much higher than those of the wild type, whereas the NS and NA mRNA levels of the mutants were comparable to the wild-type levels. By contrast, the PB2 vRNA and mRNA levels of all the tested viruses were similar, indicating that vRNA with heterologous segment-specific non-coding sequences was not affected by the mutations. The observations suggested that, with the cooperation between the homologous 5' and 3'segment-specific sequences, the introduced mutations could specifically enhance the replication of NA and NS vRNA.
Asunto(s)
Virus de la Influenza A/fisiología , ARN Viral/fisiología , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/fisiología , Replicación Viral , Regiones no Traducidas 3' , Regiones no Traducidas 5' , Línea Celular , Genoma Viral , Virus de la Influenza A/genética , Virus de la Influenza A/crecimiento & desarrollo , Neuraminidasa/genética , Neuraminidasa/metabolismo , ARN Mensajero/análisis , ARN Viral/química , Transcripción GenéticaRESUMEN
The outbreaks of avian influenza A virus in poultry and humans over the last decade posed a pandemic threat to human. Here, we discuss the basic classification and the structure of influenza A virus. The viral genome contains eight RNA viral segments and the functions of viral proteins encoded by this genome are described. In addition, the RNA transcription and replication of this virus are reviewed.
Asunto(s)
Virus de la Influenza A/fisiología , Genoma Viral , Virus de la Influenza A/clasificación , Virus de la Influenza A/genética , Virus de la Influenza A/ultraestructura , ARN Viral/genética , Transcripción Genética , Proteínas Virales/fisiología , Replicación ViralRESUMEN
BACKGROUND: A novel coronavirus (CoV) was recently identified as the agent for severe acute respiratory syndrome (SARS). We compared the abilities of conventional and real-time reverse transcription-PCR (RT-PCR) assays to detect SARS CoV in clinical specimens. METHODS: RNA samples isolated from nasopharyngeal aspirate (NPA; n = 170) and stool (n = 44) were reverse-transcribed and tested by our in-house conventional RT-PCR assay. We selected 98 NPA and 37 stool samples collected at different times after the onset of disease and tested them in a real-time quantitative RT-PCR specific for the open reading frame (ORF) 1b region of SARS CoV. Detection rates for the conventional and real-time quantitative RT-PCR assays were compared. To investigate the nature of viral RNA molecules in these clinical samples, we determined copy numbers of ORF 1b and nucleocapsid (N) gene sequences of SARS CoV. RESULTS: The quantitative real-time RT-PCR assay was more sensitive than the conventional RT-PCR assay for detecting SARS CoV in samples collected early in the course of the disease. Real-time assays targeted at the ORF 1b region and the N gene revealed that copy numbers of ORF 1b and N gene sequences in clinical samples were similar. CONCLUSIONS: NPA and stool samples can be used for early diagnosis of SARS. The real-time quantitative RT-PCR assay for SARS CoV is potentially useful for early detection of SARS CoV. Our results suggest that genomic RNA is the predominant viral RNA species in clinical samples.
Asunto(s)
Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/genética , Heces/virología , Humanos , Cavidad Nasal/virología , Faringe/virología , ARN Viral/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/aislamiento & purificación , Síndrome Respiratorio Agudo Grave/virología , Manejo de EspecímenesRESUMEN
BACKGROUND: The congenital long-QT syndrome (LQTS) is caused by mutations on several genes, all of which encode cardiac ion channels. The progressive understanding of the electrophysiological consequences of these mutations opens unforeseen possibilities for genotype-phenotype correlation studies. Preliminary observations suggested that the conditions ("triggers") associated with cardiac events may in large part be gene specific. METHODS AND RESULTS: We identified 670 LQTS patients of known genotype (LQT1, n=371; LQT2, n=234; LQT3, n=65) who had symptoms (syncope, cardiac arrest, sudden death) and examined whether 3 specific triggers (exercise, emotion, and sleep/rest without arousal) differed according to genotype. LQT1 patients experienced the majority of their events (62%) during exercise, and only 3% occurred during rest/sleep. These percentages were almost reversed among LQT2 and LQT3 patients, who were less likely to have events during exercise (13%) and more likely to have events during rest/sleep (29% and 39%). Lethal and nonlethal events followed the same pattern. Corrected QT interval did not differ among LQT1, LQT2, and LQT3 patients (498, 497, and 506 ms, respectively). The percent of patients who were free of recurrence with ss-blocker therapy was higher and the death rate was lower among LQT1 patients (81% and 4%, respectively) than among LQT2 (59% and 4%, respectively) and LQT3 (50% and 17%, respectively) patients. CONCLUSIONS: Life-threatening arrhythmias in LQTS patients tend to occur under specific circumstances in a gene-specific manner. These data allow new insights into the mechanisms that relate the electrophysiological consequences of mutations on specific genes to clinical manifestations and offer the possibility of complementing traditional therapy with gene-specific approaches.
Asunto(s)
Síndrome de QT Prolongado/genética , Antagonistas Adrenérgicos beta/uso terapéutico , Adulto , Arritmias Cardíacas/etiología , Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatología , Muerte Súbita Cardíaca/etiología , Electrocardiografía , Emociones , Ejercicio Físico , Femenino , Genotipo , Humanos , Canales Iónicos/genética , Síndrome de QT Prolongado/clasificación , Síndrome de QT Prolongado/diagnóstico , Síndrome de QT Prolongado/tratamiento farmacológico , Síndrome de QT Prolongado/fisiopatología , Masculino , Fenotipo , Factores Sexuales , Sueño , Tasa de Supervivencia , Síncope/etiologíaRESUMEN
BACKGROUND: Long-QT Syndrome (LQTS) is a cardiovascular disorder characterized by prolongation of the QT interval on ECG and presence of syncope, seizures, and sudden death. Five genes have been implicated in Romano-Ward syndrome, the autosomal dominant form of LQTS: KVLQT1, HERG, SCN5A, KCNE1, and KCNE2. Mutations in KVLQT1 and KCNE1 also cause the Jervell and Lange-Nielsen syndrome, a form of LQTS associated with deafness, a phenotypic abnormality inherited in an autosomal recessive fashion. METHODS AND RESULTS: We used mutational analyses to screen a pool of 262 unrelated individuals with LQTS for mutations in the 5 defined genes. We identified 134 mutations in addition to the 43 that we previously reported. Eighty of the mutations were novel. The total number of mutations in this population is now 177 (68% of individuals). CONCLUSIONS: KVLQT1 (42%) and HERG (45%) accounted for 87% of identified mutations, and SCN5A (8%), KCNE1 (3%), and KCNE2 (2%) accounted for the other 13%. Missense mutations were most common (72%), followed by frameshift mutations (10%), in-frame deletions, and nonsense and splice-site mutations (5% to 7% each). Most mutations resided in intracellular (52%) and transmembrane (30%) domains; 12% were found in pore and 6% in extracellular segments. In most cases (78%), a mutation was found in a single family or an individual.
Asunto(s)
Síndrome de QT Prolongado/genética , Adolescente , Adulto , Anciano , Niño , Análisis Mutacional de ADN , Femenino , Mutación del Sistema de Lectura , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mutación Missense , FenotipoRESUMEN
BACKGROUND: Congenital long-QT syndrome (LQTS) is caused by mutations of genes encoding the slow component of the delayed rectifier current (LQT1, LQT5), the rapid component of the delayed rectifier current (LQT2, LQT6), or the Na(+) current (LQT3), resulting in ST-T-wave abnormalities on the ECG. This study evaluated the spectrum of ST-T-wave patterns and repolarization parameters by genotype and determined whether genotype could be identified by ECG. METHODS AND RESULTS: ECGs of 284 gene carriers were studied to determine ST-T-wave patterns, and repolarization parameters were quantified. Genotypes were identified by individual ECG versus family-grouped ECG analysis in separate studies using ECGs of 146 gene carriers from 29 families and 233 members of 127 families undergoing molecular genotyping, respectively. Ten typical ST-T patterns (4 LQT1, 4 LQT2, and 2 LQT3) were present in 88% of LQT1 and LQT2 carriers and in 65% of LQT3 carriers. Repolarization parameters also differed by genotype. A combination of quantified repolarization parameters identified genotype with sensitivity/specificity of 85%/70% for LQT1, 83%/94% for LQT2, and 47%/63% for LQT3. Typical patterns in family-grouped ECGs best identified the genotype, being correct in 56 of 56 (21 LQT1, 33 LQT2, and 2 LQT3) families with mutation results. CONCLUSIONS: Typical ST-T-wave patterns are present in the majority of genotyped LQTS patients and can be used to identify LQT1, LQT2, and possibly LQT3 genotypes. Family-grouped ECG analysis improves genotype identification accuracy. This approach can simplify genetic screening by targeting the gene for initial study. The multiple ST-T patterns in each genotype raise questions regarding the pathophysiology and regulation of repolarization in LQTS.
Asunto(s)
Electroencefalografía/estadística & datos numéricos , Síndrome de QT Prolongado/congénito , Síndrome de QT Prolongado/diagnóstico , Adolescente , Adulto , Biomarcadores , Niño , Preescolar , Mapeo Cromosómico/estadística & datos numéricos , Diagnóstico Diferencial , Femenino , Expresión Génica , Genotipo , Humanos , Síndrome de QT Prolongado/genética , Masculino , Fenotipo , Sensibilidad y EspecificidadRESUMEN
A novel potassium channel gene has been cloned, characterized, and associated with cardiac arrhythmia. The gene encodes MinK-related peptide 1 (MiRP1), a small integral membrane subunit that assembles with HERG, a pore-forming protein, to alter its function. Unlike channels formed only with HERG, mixed complexes resemble native cardiac IKr channels in their gating, unitary conductance, regulation by potassium, and distinctive biphasic inhibition by the class III antiarrhythmic E-4031. Three missense mutations associated with long QT syndrome and ventricular fibrillation are identified in the gene for MiRP1. Mutants form channels that open slowly and close rapidly, thereby diminishing potassium currents. One variant, associated with clarithromycin-induced arrhythmia, increases channel blockade by the antibiotic. A mechanism for acquired arrhythmia is revealed: genetically based reduction in potassium currents that remains clinically silent until combined with additional stressors.
Asunto(s)
Arritmias Cardíacas/metabolismo , Proteínas de Transporte de Catión , Proteínas de Unión al ADN , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/metabolismo , Transactivadores , Secuencia de Aminoácidos , Animales , Arritmias Cardíacas/etiología , Arritmias Cardíacas/genética , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , Canal de Potasio ERG1 , Conductividad Eléctrica , Canales de Potasio Éter-A-Go-Go , Femenino , Humanos , Técnicas In Vitro , Cinética , Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/metabolismo , Datos de Secuencia Molecular , Mutación Missense , Potasio/metabolismo , Canales de Potasio/química , Canales de Potasio/genética , Conformación Proteica , Ratas , Homología de Secuencia de Aminoácido , Regulador Transcripcional ERG , Xenopus laevisRESUMEN
Long QT syndrome (LQT) is a cardiac disorder causing syncope and sudden death from arrhythmias. LQT is characterized by prolongation of the QT interval on electrocardiogram, an indicationof abnormal cardiac repolarization. Mutations in KVLQT1, HERG, SCN5A, and KCNE1, genes encoding cardiac ion channels, cause LQT. Here, we define thecomplete genomic structure of three LQT genesand use this information to identify disease-associated mutations. KVLQT1 is composed of 16 exonsand encompasses approximately 400 kb. HERG consists of 16 exons and spans 55 kb. Three exons make up KCNE1. Each intron of these genes contains the invariant GT and AG at the donor and acceptor splice sites, respectively. Intron sequences were used to design primer pairs for the amplification of all exons. Familial and sporadic cases affected bymutations in KVLQT1, HERG, and KCNE1 can nowbe genetically screened to identify individuals at risk of developing this disorder. This work has clinical implications for presymptomatic diagnosis and therapy.
Asunto(s)
Proteínas de Transporte de Catión , Proteínas de Unión al ADN , Síndrome de QT Prolongado/genética , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Transactivadores , Empalme Alternativo , Secuencia de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico , Análisis Mutacional de ADN , Cartilla de ADN , Canal de Potasio ERG1 , Canales de Potasio Éter-A-Go-Go , Exones , Femenino , Humanos , Intrones , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Síndrome de QT Prolongado/diagnóstico , Masculino , Datos de Secuencia Molecular , Mutación , Linaje , Polimorfismo Conformacional Retorcido-Simple , Regulador Transcripcional ERGRESUMEN
Jervell and Lange-Nielsen syndrome is an autosomal recessive form of long-QT syndrome. In addition to QT interval prolongation, this disorder is associated with congenital deafness. Jervell and Lange-Nielsen syndrome is rare, but affected individuals are susceptible to cardiac arrhythmias with a high incidence of sudden death and short life expectancy. A proband with Jervell and Lange-Nielsen syndrome and family members were ascertained and phenotypically characterized. Linkage, mutational, and DNA sequence analyses were used to define the genetic basis of this disorder. We found that the proband had long-QT syndrome and sensory deafness. Some family members also had QTc prolongation with an autosomal dominant pattern of inheritance, but these patients had normal hearing. The gene responsible for QTc prolongation in this family was mapped to chromosome 11p15.5 using linkage analyses. The maximum LOD score at D11S1318 was 5.46, indicating odds greater than 100,000:1 favoring linkage. Mutation analyses revealed a single base pair insertion in KVLQT11, the potassium channel gene responsible for chromosome 11-linked long-QT syndrome. This mutation caused a premature stop codon. All family members with QTc prolongation, except the proband, were heterozygous for the mutation. The proband with Jervell and Lange-Nielsen syndrome resulted from a consanguineous marriage and was homozygous for the KVLQT1 mutation. Homozygous mutation of KVLQT1 causes Jervell and Lange-Nielsen syndrome. Members of Jervell and Lange-Nielsen syndrome families should be examined for long-QT syndrome, even if they have normal hearing.
Asunto(s)
Cromosomas Humanos Par 11/genética , Sordera/genética , Síndrome de QT Prolongado/genética , Mutación , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Consanguinidad , Sordera/congénito , Genes Dominantes , Genes Recesivos , Heterocigoto , Homocigoto , Humanos , Lactante , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Escala de Lod , Persona de Mediana Edad , Modelos Genéticos , Datos de Secuencia Molecular , Linaje , Polimorfismo Conformacional Retorcido-Simple , Análisis de Secuencia de ADNAsunto(s)
Sordera/genética , Síndrome de QT Prolongado/genética , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Cromosomas Humanos Par 11 , Análisis Mutacional de ADN , Sordera/congénito , Femenino , Ligamiento Genético , Homocigoto , Humanos , Lactante , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Síndrome de QT Prolongado/congénito , Masculino , Persona de Mediana Edad , Mutación , LinajeRESUMEN
OBJECTIVES: We sought to analyze age-gender differences in the rate-corrected QT (QTc) interval in the presence of a QT-prolonging gene. BACKGROUND: Compared with men, women exhibit a longer QTc interval and an increased propensity toward torsade de pointes. In normal subjects, the QTc gender difference reflects QTc interval shortening in men during adolescence. METHODS: QTc intervals were analyzed according to age (< 16 or > or = 16 years) and gender in 460 genotyped blood relatives from families with long QT syndrome linked to chromosome 11p (KVLQT1; n = 199), 7q (HERG; n = 208) or 3p (SCN5A; n = 53). RESULTS: The mean QTc interval in genotype-negative blood relatives (n = 240) was shortest in men, but similar among women, boys and girls. For genotype-positive blood relatives, men exhibited the shortest mean QTc interval in chromosome 7q- and 11p-linked blood relatives (n = 194), but not in the smaller 3p-linked group (n = 26). Among pooled 7q- and 11p-linked blood relatives, multiple regression analysis identified both genotype (p < 0.001) and age-gender group (men vs. women/children; p < 0.001) as significant predictors of the QTc interval; and heart rate (p < 0.001), genotype (p < 0.001) and age-gender group (p = 0.01) as significant predictors of the absolute QT interval. A shorter mean QT interval in men was most evident for heart rates < 60 beats/min. CONCLUSIONS: In familial long QT syndrome linked to either chromosome 7q or 11p, men exhibit shorter mean QTc values than both women and children, for both genotype-positive and -negative blood relatives. Thus, adult gender differences in propensity toward torsade de pointes may reflect the relatively greater presence in men of a factor that blunts QT prolongation responses, especially at slow heart rates.
Asunto(s)
Frecuencia Cardíaca/fisiología , Síndrome de QT Prolongado/genética , Adolescente , Adulto , Factores de Edad , Niño , Cromosomas Humanos Par 11 , Cromosomas Humanos Par 3 , Cromosomas Humanos Par 7 , Electrocardiografía , Femenino , Ligamiento Genético , Genotipo , Frecuencia Cardíaca/genética , Humanos , Síndrome de QT Prolongado/diagnóstico , Síndrome de QT Prolongado/fisiopatología , Masculino , Análisis de Regresión , Factores Sexuales , Torsades de Pointes/genéticaRESUMEN
Genetic factors contribute to the risk of sudden death from cardiac arrhythmias. Here, positional cloning methods establish KVLQT1 as the chromosome 11-linked LQT1 gene responsible for the most common inherited cardiac arrhythmia. KVLQT1 is strongly expressed in the heart and encodes a protein with structural features of a voltage-gated potassium channel. KVLQT1 mutations are present in affected members of 16 arrhythmia families, including one intragenic deletion and ten different missense mutations. These data define KVLQT1 as a novel cardiac potassium channel gene and show that mutations in this gene cause susceptibility to ventricular tachyarrhythmias and sudden death.
Asunto(s)
Síndrome de QT Prolongado/genética , Canales de Potasio/genética , Secuencia de Aminoácidos , Secuencia de Bases , Cromosomas Humanos Par 11 , Clonación Molecular , Femenino , Ligamiento Genético , Humanos , Masculino , Datos de Secuencia Molecular , Linaje , Mutación Puntual , Polimorfismo Conformacional Retorcido-Simple , Alineación de Secuencia , Eliminación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
To identify genes involved in cardiac arrhythmia, we investigated patients with long QT syndrome (LQT), an inherited disorder causing sudden death from a ventricular tachyarrythmia, torsade de pointes. We previously mapped LQT loci on chromosomes 11 (LQT1), 7 (LQT2), and 3 (LQT3). Here, linkage and physical mapping place LQT2 and a putative potassium channel gene, HERG, on chromosome 7q35-36. Single strand conformation polymorphism and DNA sequence analyses reveal HERG mutations in six LQT families, including two intragenic deletions, one splice-donor mutation, and three missense mutations. In one kindred, the mutation arose de novo. Northern blot analyses show that HERG is strongly expressed in the heart. These data indicate that HERG is LQT2 and suggest a likely cellular mechanism for torsade de pointes.