RESUMO
BACKGROUND. In patients with prostate cancer, PET using targeted radiotracers can identify increased activity in small morphologically normal lymph nodes, facilitating earlier detection of metastatic disease. OBJECTIVE. The purpose of this article was to assess the efficacy and safety of CT-guided biopsy of suspicious pelvic and retroperitoneal lymph nodes measuring smaller than 1 cm detected by 11C-choline PET in patients with prostate cancer, with comparison with nodes measuring 1 cm or larger. METHODS. This retrospective study included patients with prostate cancer who underwent CT-guided percutaneous biopsy of suspicious pelvic or retroperitoneal lymph nodes detected by 11C-choline PET/CT or PET/MRI (performed because of a rising or elevated PSA level or known recurrent or metastatic disease) between June 1, 2012, and March 20, 2020. Patient, lymph node, and procedural characteristics, as well as biopsy outcomes and complications, were recorded. Biopsies of lymph nodes measuring smaller than 1 cm and of lymph nodes measuring 1 cm and larger were compared. RESULTS. A total of 269 patients (mean age, 68.7 ± 6.8 [SD] years) were included. A total of 156 patients underwent biopsy of lymph nodes measuring smaller than 1 cm (range, 3-9 mm); 113 patients underwent biopsy of lymph nodes measuring 1 cm or larger (range, 10-35 mm). Lymph nodes smaller than 1 cm and lymph nodes 1 cm and larger showed no significant difference in diagnostic yield (89.7% vs 92.9%; p = .40). Diagnostic yield was not significantly different between nodes smaller than 1 cm and nodes 1 cm and larger for any individual anatomic location within the pelvis or retroperitoneum (all p > .05). Malignant yield was lower for nodes smaller than 1 cm than for nodes 1 cm and larger (44.9% vs 63.7%; p = .003). The single biopsied 3-mm node had a nondiagnostic specimen. Diagnostic yield and malignant yield were 100.0% and 40.0%, respectively, for 4-mm nodes, and 95.5% and 45.5%, respectively, for 5-mm nodes. Patients with nodes smaller than 1 cm and nodes 1 cm and larger showed no significant difference in minor (12.8% vs 7.1%; p = .16) or major (0.6% vs 2.7%; p = .31) complication rate. CONCLUSION. The findings support the safety and efficacy of CT-guided biopsy of suspicious subcentimeter pelvic and retroperitoneal lymph nodes detected on 11C-choline PET in patients with prostate cancer. CLINICAL IMPACT. Earlier diagnosis of metastatic lymphadenopathy will impact prognostic assessment and management decisions in patients with recurrent prostate cancer.
Assuntos
Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Neoplasias da Próstata , Masculino , Humanos , Pessoa de Meia-Idade , Idoso , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Estudos Retrospectivos , Colina , Recidiva Local de Neoplasia/patologia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia , Linfonodos/diagnóstico por imagem , Linfonodos/patologia , Tomografia Computadorizada por Raios X , Tomografia por Emissão de Pósitrons/métodos , Pelve/diagnóstico por imagem , Pelve/patologia , BiópsiaRESUMO
BACKGROUND: The genotype-phenotype correlation of SCN5A mutations as a predictor of cardiac events in Brugada syndrome remains controversial. We aimed to establish a registry limited to probands, with a long follow-up period, so that the genotype-phenotype correlation of SCN5A mutations in Brugada syndrome can be examined without patient selection bias. METHODS: This multicenter registry enrolled 415 probands (n=403; men, 97%; age, 46±14 years) diagnosed with Brugada syndrome whose SCN5A gene was analyzed for mutations. RESULTS: During a mean follow-up period of 72 months, the overall cardiac event rate was 2.5%/y. In comparison with probands without mutations (SCN5A (-), n=355), probands with SCN5A mutations (SCN5A (+), n=60) experienced their first cardiac event at a younger age (34 versus 42 years, P=0.013), had a higher positive rate of late potentials (89% versus 73%, P=0.016), exhibited longer P-wave, PQ, and QRS durations, and had a higher rate of cardiac events (P=0.017 by log-rank). Multivariate analysis indicated that only SCN5A mutation and history of aborted cardiac arrest were significant predictors of cardiac events (SCN5A (+) versus SCN5A (-): hazard ratio, 2.0 and P=0.045; history of aborted cardiac arrest versus no such history: hazard ratio, 6.5 and P<0.001). CONCLUSIONS: Brugada syndrome patients with SCN5A mutations exhibit more conduction abnormalities on ECG and have higher risk for cardiac events.
Assuntos
Síndrome de Brugada/genética , Eletrocardiografia , Genótipo , Mutação/genética , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Fenótipo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Síndrome de Brugada/epidemiologia , Síndrome de Brugada/fisiopatologia , Criança , Pré-Escolar , Eletrocardiografia/métodos , Feminino , Seguimentos , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Adulto JovemRESUMO
BACKGROUND: Variable expressivity and incomplete penetrance between individuals with identical long QT syndrome (LQTS) causative mutations largely remain unexplained. Founder populations provide a unique opportunity to explore modifying genetic effects. We examined the role of a novel synonymous KCNQ1 p.L353L variant on the splicing of exon 8 and on heart rate corrected QT interval (QTc) in a population known to have a pathogenic LQTS type 1 (LQTS1) causative mutation, p.V205M, in KCNQ1-encoded Kv7.1. METHODS: 419 adults were genotyped for p.V205M, p.L353L and a previously described QTc modifier (KCNH2-p.K897T). Adjusted linear regression determined the effect of each variant on QTc, alone and in combination. In addition, peripheral blood RNA was extracted from three controls and three p.L353L-positive individuals. The mutant transcript levels were assessed via qPCR and normalised to overall KCNQ1 transcript levels to assess the effect on splicing. RESULTS: For women and men, respectively, p.L353L alone conferred a 10.0 (p=0.064)â ms and 14.0 (p=0.014)â ms increase in QTc and in men only a significant interaction effect in combination with the p.V205M (34.6â ms, p=0.003) resulting in a QTc of â¼500â ms. The mechanism of p.L353L's effect was attributed to approximately threefold increase in exon 8 exclusion resulting in â¼25% mutant transcripts of the total KCNQ1 transcript levels. CONCLUSIONS: Our results provide the first evidence that synonymous variants outside the canonical splice sites in KCNQ1 can alter splicing and clinically impact phenotype. Through this mechanism, we identified that p.L353L can precipitate QT prolongation by itself and produce a clinically relevant interactive effect in conjunction with other LQTS variants.
Assuntos
Canal de Potássio KCNQ1/genética , Splicing de RNA/genética , Síndrome de Romano-Ward/genética , Arritmias Cardíacas/genética , Éxons/genética , Feminino , Genótipo , Humanos , Masculino , Mutação/genética , FenótipoRESUMO
IMPORTANCE: Large-scale DNA sequencing identifies incidental rare variants in established Mendelian disease genes, but the frequency of related clinical phenotypes in unselected patient populations is not well established. Phenotype data from electronic medical records (EMRs) may provide a resource to assess the clinical relevance of rare variants. OBJECTIVE: To determine the clinical phenotypes from EMRs for individuals with variants designated as pathogenic by expert review in arrhythmia susceptibility genes. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study included 2022 individuals recruited for nonantiarrhythmic drug exposure phenotypes from October 5, 2012, to September 30, 2013, for the Electronic Medical Records and Genomics Network Pharmacogenomics project from 7 US academic medical centers. Variants in SCN5A and KCNH2, disease genes for long QT and Brugada syndromes, were assessed for potential pathogenicity by 3 laboratories with ion channel expertise and by comparison with the ClinVar database. Relevant phenotypes were determined from EMRs, with data available from 2002 (or earlier for some sites) through September 10, 2014. EXPOSURES: One or more variants designated as pathogenic in SCN5A or KCNH2. MAIN OUTCOMES AND MEASURES: Arrhythmia or electrocardiographic (ECG) phenotypes defined by International Classification of Diseases, Ninth Revision (ICD-9) codes, ECG data, and manual EMR review. RESULTS: Among 2022 study participants (median age, 61 years [interquartile range, 56-65 years]; 1118 [55%] female; 1491 [74%] white), a total of 122 rare (minor allele frequency <0.5%) nonsynonymous and splice-site variants in 2 arrhythmia susceptibility genes were identified in 223 individuals (11% of the study cohort). Forty-two variants in 63 participants were designated potentially pathogenic by at least 1 laboratory or ClinVar, with low concordance across laboratories (Cohen κ = 0.26). An ICD-9 code for arrhythmia was found in 11 of 63 (17%) variant carriers vs 264 of 1959 (13%) of those without variants (difference, +4%; 95% CI, -5% to +13%; P = .35). In the 1270 (63%) with ECGs, corrected QT intervals were not different in variant carriers vs those without (median, 429 vs 439 milliseconds; difference, -10 milliseconds; 95% CI, -16 to +3 milliseconds; P = .17). After manual review, 22 of 63 participants (35%) with designated variants had any ECG or arrhythmia phenotype, and only 2 had corrected QT interval longer than 500 milliseconds. CONCLUSIONS AND RELEVANCE: Among laboratories experienced in genetic testing for cardiac arrhythmia disorders, there was low concordance in designating SCN5A and KCNH2 variants as pathogenic. In an unselected population, the putatively pathogenic genetic variants were not associated with an abnormal phenotype. These findings raise questions about the implications of notifying patients of incidental genetic findings.
Assuntos
Arritmias Cardíacas/genética , Registros Eletrônicos de Saúde , Canais de Potássio Éter-A-Go-Go/genética , Variação Genética , Laboratórios/normas , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Fenótipo , Idoso , Idoso de 80 Anos ou mais , Alelos , Arritmias Cardíacas/etnologia , Arritmias Cardíacas/fisiopatologia , Síndrome de Brugada/genética , Canal de Potássio ERG1 , Feminino , Predisposição Genética para Doença , Testes Genéticos/normas , Genômica , Heterozigoto , Humanos , Achados Incidentais , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Estudos Prospectivos , Distribuição Aleatória , Estatísticas não Paramétricas , Adulto JovemRESUMO
BACKGROUND: Prolonged survival of patients with metastatic disease has furthered interest in metastasis-directed therapy (MDT). RESEARCH QUESTION: There is a paucity of data comparing lung MDT modalities. Do outcomes among sublobar resection (SLR), stereotactic body radiation therapy (SBRT), and percutaneous ablation (PA) for lung metastases vary in terms of local control and survival? STUDY DESIGN AND METHODS: Medical records of patients undergoing lung MDT at a single cancer center between January 2015 and December 2020 were reviewed. Overall survival, local progression, and toxicity outcomes were collected. Patient and lesion characteristics were used to generate multivariable models with propensity weighted analysis. RESULTS: Lung MDT courses (644 total: 243 SLR, 274 SBRT, 127 PA) delivered to 511 patients were included with a median follow-up of 22 months. There were 47 local progression events in 45 patients, and 159 patients died. Two-year overall survival and local progression were 80.3% and 63.3%, 83.8% and 9.6%, and 4.1% and 11.7% for SLR, SBRT, and PA, respectively. Lesion size per 1 cm was associated with worse overall survival (hazard ratio, 1.24; P = .003) and LP (hazard ratio, 1.50; P < .001). There was no difference in overall survival by modality. Relative to SLR, there was no difference in risk of local progression with PA; however, SBRT was associated with a decreased risk (hazard ratio, 0.26; P = .023). Rates of severe toxicity were low (2.1%-2.6%) and not different among groups. INTERPRETATION: This study performs a propensity weighted analysis of SLR, SBRT, and PA and shows no impact of lung MDT modality on overall survival. Given excellent local control across MDT options, a multidisciplinary approach is beneficial for patient triage and longitudinal management.
Assuntos
Neoplasias Pulmonares , Radiocirurgia , Humanos , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/radioterapia , Radiocirurgia/métodos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Estudos Retrospectivos , Pneumonectomia/métodos , Resultado do Tratamento , Taxa de Sobrevida , Pontuação de PropensãoRESUMO
AIMS: Heterozygous mutations in KCNQ1 cause type 1 long QT syndrome (LQT1), a disease characterized by prolonged heart rate-corrected QT interval (QTc) and life-threatening arrhythmias. It is unknown why disease penetrance and expressivity is so variable between individuals hosting identical mutations. We aimed to study whether this can be explained by single nucleotide polymorphisms (SNPs) in KCNQ1's 3' untranslated region (3'UTR). METHODS AND RESULTS: This study was performed in 84 LQT1 patients from the Academic Medical Center in Amsterdam and validated in 84 LQT1 patients from the Mayo Clinic in Rochester. All patients were genotyped for SNPs in KCNQ1's 3'UTR, and six SNPs were found. Single nucleotide polymorphisms rs2519184, rs8234, and rs10798 were associated in an allele-specific manner with QTc and symptom occurrence. Patients with the derived SNP variants on their mutated KCNQ1 allele had shorter QTc and fewer symptoms, while the opposite was also true: patients with the derived SNP variants on their normal KCNQ1 allele had significantly longer QTc and more symptoms. Luciferase reporter assays showed that the expression of KCNQ1's 3'UTR with the derived SNP variants was lower than the expression of the 3'UTR with the ancestral SNP variants. CONCLUSION: Our data indicate that 3'UTR SNPs potently modify disease severity in LQT1. The allele-specific effects of the SNPs on disease severity and gene expression strongly suggest that they are functional variants that directly alter the expression of the allele on which they reside, and thereby influence the balance between proteins stemming from either the normal or the mutant KCNQ1 allele.
Assuntos
Regiões 3' não Traduzidas/genética , Canal de Potássio KCNQ1/genética , Mutação/genética , Polimorfismo de Nucleotídeo Único/genética , Síndrome de Romano-Ward/genética , Adulto , Alelos , Animais , Eletrocardiografia , Feminino , Variação Genética , Heterozigoto , Humanos , Luciferases/metabolismo , Masculino , Miócitos Cardíacos/enzimologia , Ratos , Síndrome de Romano-Ward/enzimologia , TransfecçãoRESUMO
BACKGROUND: Mutations in the KCNQ1-encoded Kv7.1 potassium channel cause long QT syndrome (LQTS) type 1 (LQT1). It has been suggested that â¼10%-20% of rare LQTS case-derived variants in the literature may have been published erroneously as LQT1-causative mutations and may be "false positives." OBJECTIVE: The purpose of this study was to determine which previously published KCNQ1 case variants are likely false positives. METHODS: A list of all published, case-derived KCNQ1 missense variants (MVs) was compiled. The occurrence of each MV within the Genome Aggregation Database (gnomAD) was assessed. Eight in silico tools were used to predict each variant's pathogenicity. Case-derived variants that were either (1) too frequently found in gnomAD or (2) absent in gnomAD but predicted to be pathogenic by ≤2 tools were considered potential false positives. Three of these variants were characterized functionally using whole-cell patch clamp technique. RESULTS: Overall, there were 244 KCNQ1 case-derived MVs. Of these, 29 (12%) were seen in ≥10 individuals in gnomAD and are demotable. However, 157 of 244 MVs (64%) were absent in gnomAD. Of these, 7 (4%) were predicted to be pathogenic by ≤2 tools, 3 of which we characterized functionally. There was no significant difference in current density between heterozygous KCNQ1-F127L, -P477L, or -L619M variant-containing channels compared to KCNQ1-WT. CONCLUSION: This study offers preliminary evidence for the demotion of 32 (13%) previously published LQT1 MVs. Of these, 29 were demoted because of their frequent sighting in gnomAD. Additionally, in silico analysis and in vitro functional studies have facilitated the demotion of 3 ultra-rare MVs (F127L, P477L, L619M).
Assuntos
Biologia Computacional/métodos , DNA/genética , Sistema de Condução Cardíaco/patologia , Canal de Potássio KCNQ1/genética , Mutação , Síndrome de Romano-Ward/genética , Células Cultivadas , Análise Mutacional de DNA , Feminino , Sistema de Condução Cardíaco/metabolismo , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Canal de Potássio KCNQ1/metabolismo , Masculino , Técnicas de Patch-Clamp , Fenótipo , Síndrome de Romano-Ward/metabolismo , Síndrome de Romano-Ward/fisiopatologiaRESUMO
BACKGROUND: Pathogenic RYR2 variants account for ≈60% of clinically definite cases of catecholaminergic polymorphic ventricular tachycardia. However, the rate of rare benign RYR2 variants identified in the general population remains a challenge for genetic test interpretation. Therefore, we examined the results of the RYR2 genetic test among patients referred for commercial genetic testing and examined factors impacting variant interpretability. METHODS: Frequency and location comparisons were made for RYR2 variants identified among 1355 total patients of varying clinical certainty and 60 706 Exome Aggregation Consortium controls. The impact of the clinical phenotype on the yield of RYR2 variants was examined. Six in silico tools were assessed using patient- and control-derived variants. RESULTS: A total of 18.2% (218/1200) of patients referred for commercial testing hosted rare RYR2 variants, statistically less than the 59% (46/78) yield among clinically definite cases, resulting in a much higher potential genetic false discovery rate among referrals considering the 3.2% background rate of rare, benign RYR2 variants. Exclusion of clearly putative pathogenic variants further complicates the interpretation of the next novel RYR2 variant. Exonic/topologic analyses revealed overrepresentation of patient variants in exons covering only one third of the protein. In silico tools largely failed to show evidence toward enhancement of variant interpretation. CONCLUSIONS: Current expert recommendations have resulted in increased use of RYR2 genetic testing in patients with questionable clinical phenotypes. Using the largest to date catecholaminergic polymorphic ventricular tachycardia patient versus control comparison, this study highlights important variables in the interpretation of variants to overcome the 3.2% background rate that confounds RYR2 variant interpretation.
Assuntos
Canal de Liberação de Cálcio do Receptor de Rianodina , Taquicardia Ventricular , Exoma , Testes Genéticos , Variação Genética , Genótipo , Humanos , Mutação , Fenótipo , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/genéticaRESUMO
BACKGROUND: Long QT syndrome type 3 (LQT3) accounts for 5%-10% of long QT syndrome and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Approximately 2% of healthy individuals host rare SCN5A variants of uncertain significance (VUS). Distinction of true LQT3-causative mutations from background genetic noise is essential. OBJECTIVE: The purpose of this study was to assess the use of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3. METHODS: We reviewed the LAT results and medical records for 25 patients with a possible LQT3-associated SCN5A variant. The LAT involved a loading dose of 1 mg/kg of intravenous lidocaine followed by continuous infusion at 50 µg/(kgâ min) for 20 minutes. If the corrected QT interval shortened by ≥30 ms, the LAT was defined as positive. RESULTS: Sixteen patients (64%) had a positive LAT, 6 of which demonstrated the E1784K variant. A positive LAT correlated in 86% of cases with abnormal in vitro channel function (mean corrected QT interval attenuation 43 ± 3 ms vs 25 ± 5 ms for wild-type variants; P = .03). Four of 5 patients (80%) with a VUS had a positive LAT (T1304M [2 patients], L1786P, and R800L). The T1304M variant demonstrated abnormal in vitro function and a positive LAT, opening the door for a potential variant promotion from VUS to likely pathogenic. CONCLUSION: The LAT may help distinguish true LQT3-causative mutations from an otherwise noncontributory VUS. Given that lidocaine acts as a late sodium current blocker, a positive LAT may enable the early identification of a pathological accentuation of the late sodium current that could be targeted therapeutically.
Assuntos
Doença do Sistema de Condução Cardíaco/tratamento farmacológico , Eletrocardiografia/efeitos dos fármacos , Lidocaína/farmacologia , Síndrome do QT Longo/tratamento farmacológico , Mutação , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Adolescente , Doença do Sistema de Condução Cardíaco/genética , Doença do Sistema de Condução Cardíaco/metabolismo , Análise Mutacional de DNA , Feminino , Genótipo , Frequência Cardíaca/efeitos dos fármacos , Humanos , Síndrome do QT Longo/genética , Síndrome do QT Longo/metabolismo , Masculino , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Estudos Retrospectivos , Resultado do Tratamento , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologia , Adulto JovemRESUMO
Sudden infant death syndrome (SIDS) is the leading cause of post-neonatal infant mortality in developed countries, characterized by the death of infants for no obvious reason and without prior warning. The complex interaction of multiple factors in the pathogenesis of SIDS is illustrated by the 'triple risk hypothesis', which proposed that SIDS results from a convergence of three overlapping risk factors: a critical developmental period, an exogenous stressor, and underlying genetic and/or nongenetic vulnerability in the infant. Rare variants in genes associated with inherited arrhythmia syndromes and cardiomyopathies have been proposed as the substrate for an infant's critical vulnerability in a small subset of SIDS cases. Given the potential risk of inherited cardiac disease, current guidelines recommend post-mortem genetic testing (molecular autopsy) and cardiological investigation of the surviving family, complemented by targeted genetic testing if appropriate. In this Review, we highlight the latest developments in understanding the spectrum and prevalence of cardiac-mediated SIDS, and discuss the clinical implications of SIDS in the surviving family and the general population.
Assuntos
Cardiopatias/complicações , Morte Súbita do Lactente/etiologia , Testes Genéticos/métodos , Saúde Global , Cardiopatias/congênito , Cardiopatias/diagnóstico , Humanos , Lactente , Mortalidade Infantil/tendências , Fatores de Risco , Morte Súbita do Lactente/diagnóstico , Morte Súbita do Lactente/epidemiologiaRESUMO
Genetic testing for hypertrophic cardiomyopathy (HCM) can provide an important clinical marker for disease outcome and family screening. This study set out to validate our recently developed phenotype-based HCM genotype predictor score. Patients clinically diagnosed with HCM and evaluated by genetic counselors comprised the study cohort. Genotype score was derived based on clinical and echocardiographic variables. Total score was correlated with the yield of genetic testing. Of 564 HCM patients, 198 sought genetic testing (35 %; 55 % male; mean age at diagnosis, 50 ± 20 years). Of these, 101 patients (51 %) were genotype positive for a HCM-associated genetic mutation (55 % male; mean age at diagnosis, 42 ± 18 years). Cochran-Armitage analysis showed similar, statistically significant trends of increased yields for higher genotype scores for both the original and study cohort. Validated by the current study, this scoring system provides an easy-to-use, clinical tool to aid in determining the likelihood of a positive HCM genetic test.
Assuntos
Cardiomiopatia Hipertrófica/diagnóstico , Cardiomiopatia Hipertrófica/genética , Análise Mutacional de DNA , Técnicas de Apoio para a Decisão , Aconselhamento Genético , Mutação , Adulto , Idoso , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Ecocardiografia , Registros Eletrônicos de Saúde , Feminino , Marcadores Genéticos , Predisposição Genética para Doença , Hereditariedade , Humanos , Masculino , Pessoa de Meia-Idade , Minnesota , Linhagem , Fenótipo , Valor Preditivo dos Testes , Prognóstico , Reprodutibilidade dos Testes , Estudos Retrospectivos , Medição de Risco , Fatores de RiscoRESUMO
We illustrate the work necessary to reverse course after identification of a KCNQ1 variant interpreted erroneously as causing long QT syndrome (LQTS) and to identify the true cause of a case of sudden death in the young. Surrogate genetic testing of a decedent's living brother identified a rare KCNQ1-V133I variant, which prompted an implantable cardioverter defibrillator and subsequent diagnosis of LQTS in other family members. Subsequently, this presumed LQT1 family came to our institution for further clinical evaluation and research-based investigations, including KCNQ1-V133I variant-specific analysis of the decedent, heterologous expression studies of KCNQ1-V133I, and a whole-exome molecular autopsy along with genomic triangulation using his unaffected parents' DNA. After evaluating several V133I-positive family members, clinical doubt was cast on the veracity of the previously levied diagnosis of LQT1, resulting in a re-opening of the case and an intense pursuit of the lethal substrate. Furthermore, the decedent tested negative for V133I, and heterologous expression studies demonstrated a normal cellular phenotype for V133I-containing Kv7.1 channels. Instead, after whole-exome molecular autopsy, a de novo pathogenic variant (p.R454W) in DES-encoded desmin was identified. As detailed herein, the forensic evaluation of sudden death in the young requires meticulous focus on the decedent followed by a careful and deliberate assessment of the decedent's relatives. Surrogate genetic testing can have disastrous consequences and should be avoided. Genetic test results require careful scrutiny to avoid unintended and potentially devastating repercussions. Although the root cause of the decedent's tragic death would have remained a mystery, the unintended consequences for the living relatives described herein might have been avoided based on clinical grounds alone. All family members had electrocardiograms with normal QT intervals, making the diagnosis of familial LQTS unlikely. As such, if the clinicians caring for these patients had focused solely on clinical data from the survivors, there might have been no reason to embark on a path of inappropriate treatment based on genetic testing.
RESUMO
BACKGROUND: A 2% to 5% background rate of rare SCN5A nonsynonymous single nucleotide variants (nsSNVs) among healthy individuals confounds clinical genetic testing. Therefore, the purpose of this study was to enhance interpretation of SCN5A nsSNVs for clinical genetic testing using estimated predictive values derived from protein-topology and 7 in silico tools. METHODS AND RESULTS: Seven in silico tools were used to assign pathogenic/benign status to nsSNVs from 2888 long-QT syndrome cases, 2111 Brugada syndrome cases, and 8975 controls. Estimated predictive values were determined for each tool across the entire SCN5A-encoded Na(v)1.5 channel as well as for specific topographical regions. In addition, the in silico tools were assessed for their ability to correlate with cellular electrophysiology studies. In long-QT syndrome, transmembrane segments S3-S5+S6 and the DIII/DIV linker region were associated with high probability of pathogenicity. For Brugada syndrome, only the transmembrane spanning domains had a high probability of pathogenicity. Although individual tools distinguished case- and control-derived SCN5A nsSNVs, the composite use of multiple tools resulted in the greatest enhancement of interpretation. The use of the composite score allowed for enhanced interpretation for nsSNVs outside of the topological regions that intrinsically had a high probability of pathogenicity, as well as within the transmembrane spanning domains for Brugada syndrome nsSNVs. CONCLUSIONS: We have used a large case/control study to identify regions of Na(v)1.5 associated with a high probability of pathogenicity. Although topology alone would leave the variants outside these identified regions in genetic purgatory, the synergistic use of multiple in silico tools may help promote or demote a variant's pathogenic status.
Assuntos
Síndrome de Brugada/genética , Predisposição Genética para Doença/genética , Síndrome do QT Longo/genética , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Polimorfismo de Nucleotídeo Único , Sequência de Aminoácidos , Síndrome de Brugada/classificação , Síndrome de Brugada/fisiopatologia , Estudos de Casos e Controles , Biologia Computacional/métodos , Simulação por Computador , Eletrofisiologia , Frequência do Gene , Humanos , Síndrome do QT Longo/classificação , Síndrome do QT Longo/fisiopatologia , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Canal de Sódio Disparado por Voltagem NAV1.5/química , Canal de Sódio Disparado por Voltagem NAV1.5/fisiologia , Fenótipo , Estrutura Secundária de ProteínaRESUMO
Despite the overrepresentation of Kv7.1 mutations among patients with a robust diagnosis of long QT syndrome (LQTS), a background rate of innocuous Kv7.1 missense variants observed in healthy controls creates ambiguity in the interpretation of LQTS genetic test results. A recent study showed that the probability of pathogenicity for rare missense mutations depends in part on the topological location of the variant in Kv7.1's various structure-function domains. Since the Kv7.1's C-terminus accounts for nearly 50 % of the overall protein and nearly 50 % of the overall background rate of rare variants falls within the C-terminus, further enhancement in mutation calling may provide guidance in distinguishing pathogenic long QT syndrome type 1 (LQT1)-causing mutations from rare non-disease-causing variants in the Kv7.1's C-terminus. Therefore, we have used conservation analysis and a large case-control study to generate topology-based estimative predictive values to aid in interpretation, identifying three regions of high conservation within the Kv7.1's C-terminus which have a high probability of LQT1 pathogenicity.
Assuntos
Simulação por Computador , Canal de Potássio KCNQ1/genética , Mutação de Sentido Incorreto , Síndrome de Romano-Ward/genética , Sequência de Aminoácidos , Estudos de Casos e Controles , Sequência Conservada , Análise Mutacional de DNA , Bases de Dados Genéticas , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Canal de Potássio KCNQ1/metabolismo , Fenótipo , Valor Preditivo dos Testes , Conformação Proteica , Fatores de Risco , Síndrome de Romano-Ward/diagnóstico , Síndrome de Romano-Ward/metabolismo , Síndrome de Romano-Ward/fisiopatologia , Relação Estrutura-AtividadeRESUMO
Despite the significant progress that has been made in identifying disease-associated mutations, the utility of the hypertrophic cardiomyopathy (HCM) genetic test is limited by a lack of understanding of the background genetic variation inherent to these sarcomeric genes in seemingly healthy subjects. This study represents the first comprehensive analysis of genetic variation in 427 ostensibly healthy individuals for the HCM genetic test using the "gold standard" Sanger sequencing method validating the background rate identified in the publically available exomes. While mutations are clearly overrepresented in disease, a background rate as high as â¼5 % among healthy individuals prevents diagnostic certainty. To this end, we have identified a number of estimated predictive value-based associations including gene-specific, topology, and conservation methods generating an algorithm aiding in the probabilistic interpretation of an HCM genetic test.
Assuntos
Cardiomiopatia Hipertrófica/diagnóstico , Cardiomiopatia Hipertrófica/genética , Testes Genéticos/métodos , Genômica/métodos , Análise de Sequência de DNA/métodos , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético , Sarcômeros/genética , Adulto JovemRESUMO
BACKGROUND: Hundreds of nonsynonymous single nucleotide variants (nsSNVs) have been identified in the 2 most common long-QT syndrome-susceptibility genes (KCNQ1 and KCNH2). Unfortunately, an ≈3% BACKGROUND: and KCNH2 nsSNVs amongst healthy individuals complicates the ability to distinguish rare pathogenic mutations from similarly rare yet presumably innocuous variants. METHODS AND RESULTS: In this study, 4 tools [(1) conservation across species, (2) Grantham values, (3) sorting intolerant from tolerant, and (4) polymorphism phenotyping] were used to predict pathogenic or benign status for nsSNVs identified across 388 clinically definite long-QT syndrome cases and 1344 ostensibly healthy controls. From these data, estimated predictive values were determined for each tool independently, in concert with previously published protein topology-derived estimated predictive values, and synergistically when ≥3 tools were in agreement. Overall, all 4 tools displayed a statistically significant ability to distinguish between case-derived and control-derived nsSNVs in KCNQ1, whereas each tool, except Grantham values, displayed a similar ability to differentiate KCNH2 nsSNVs. Collectively, when at least 3 of the 4 tools agreed on the pathogenic status of C-terminal nsSNVs located outside the KCNH2/Kv11.1 cyclic nucleotide-binding domain, the topology-specific estimated predictive value improved from 56% to 91%. CONCLUSIONS: Although in silico prediction tools should not be used to predict independently the pathogenicity of a novel, rare nSNV, our results support the potential clinical use of the synergistic utility of these tools to enhance the classification of nsSNVs, particularly for Kv11.1's difficult to interpret C-terminal region.
Assuntos
Síndrome do QT Longo/genética , Síndrome de Romano-Ward/genética , Algoritmos , Estudos de Casos e Controles , Biologia Computacional , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/química , Canais de Potássio Éter-A-Go-Go/genética , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos , Canal de Potássio KCNQ1/química , Canal de Potássio KCNQ1/genética , Canal de Potássio KCNQ1/metabolismo , Síndrome do QT Longo/classificação , Síndrome do QT Longo/patologia , Fenótipo , Filogenia , Polimorfismo de Nucleotídeo Único , Estrutura Terciária de Proteína , Síndrome de Romano-Ward/classificação , Síndrome de Romano-Ward/patologiaAssuntos
Medicina de Precisão , Incerteza , Morte Súbita Cardíaca , Genótipo , Parada Cardíaca , Humanos , MutaçãoRESUMO
OBJECTIVES: The aims of this study were to determine the spectrum and prevalence of "background genetic noise" in the arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) genetic test and to determine genetic associations that can guide the interpretation of a positive test result. BACKGROUND: ARVC is a potentially lethal genetic cardiovascular disorder characterized by myocyte loss and fibrofatty tissue replacement of the right ventricle. Genetic variation among the ARVC susceptibility genes has not been systematically examined, and little is known about the background noise associated with the ARVC genetic test. METHODS: Using direct deoxyribonucleic acid sequencing, the coding exons/splice junctions of PKP2, DSP, DSG2, DSC2, and TMEM43 were genotyped for 93 probands diagnosed with ARVC from the Netherlands and 427 ostensibly healthy controls of various ethnicities. Eighty-two additional ARVC cases were obtained from published reports, and additional mutations were included from the ARVD/C Genetic Variants Database. RESULTS: The overall yield of mutations among ARVC cases was 58% versus 16% in controls. Radical mutations were hosted by 0.5% of control individuals versus 43% of ARVC cases, while 16% of controls hosted missense mutations versus a similar 21% of ARVC cases. Relative to controls, mutations in cases occurred more frequently in non-Caucasians, localized to the N-terminal regions of DSP and DSG2, and localized to highly conserved residues within PKP2 and DSG2. CONCLUSIONS: This study is the first to comprehensively evaluate genetic variation in healthy controls for the ARVC susceptibility genes. Radical mutations are high-probability ARVC-associated mutations, whereas rare missense mutations should be interpreted in the context of race and ethnicity, mutation location, and sequence conservation.