Margherita Torchio - Academia.edu (original) (raw)

Papers by Margherita Torchio

Research paper thumbnail of Characterization of SEMA3A-encoded semaphorin as a naturally occurring Kv4.3 protein inhibitor and its contribution to Brugada syndrome

Circulation research, 2014

Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in ... more Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in the nervous and cardiac systems. In addition, SEMA3A has an amino acid motif that is analogous to hanatoxin, an inhibitor of voltage-gated K(+) channels. SEMA3A-knockout mice exhibit an abnormal ECG pattern and are prone to ventricular arrhythmias and sudden cardiac death. Our aim was to determine whether SEMA3A is a naturally occurring protein inhibitor of Kv4.3 (Ito) channels and its potential contribution to Brugada syndrome. Kv4.3, Nav1.5, Cav1.2, or Kv4.2 were coexpressed or perfused with SEMA3A in HEK293 cells, and electrophysiological properties were examined via whole-cell patch clamp technique. SEMA3A selectively altered Kv4.3 by significantly reducing peak current density without perturbing Kv4.3 cell surface protein expression. SEMA3A also reduced Ito current density in cardiomyocytes derived from human-induced pluripotent stem cells. Disruption of a putative toxin binding dom...

Research paper thumbnail of Role of common and rare variants in SCN10A: Results from the Brugada syndrome QRS locus gene discovery collaborative study

Cardiovascular research, Jan 17, 2015

Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac co... more Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration. A multi-centre study sequenced 7 candidate genes (SCN10A, HAND1, PLN, CASQ2, TKT, TBΧ3 and ΤΒΧ5) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A, were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for 4/7 probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A) showed co-segregation. Th...

Research paper thumbnail of Common variants at SCN5A-SCN10A and HEY2 are associated with Brugada syndrome, a rare disease with high risk of sudden cardiac death

Nature Genetics, 2013

Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in ar... more Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in around 20% of cases 1-3. Through a genome-wide association study of 312 individuals with Brugada syndrome and 1,115 controls, we detected 2 significant association signals at the SCN10A locus (rs10428132) and near the HEY2 gene (rs9388451). Independent replication confirmed both signals (meta-analyses: rs10428132, P = 1.0 × 10 −68 ; rs9388451, P = 5.1 × 10 −17) and identified one additional signal in SCN5A (at 3p21; rs11708996, P = 1.0 × 10 −14). The cumulative effect of the three loci on disease susceptibility was unexpectedly large (P trend = 6.1 × 10 −81). The association signals at SCN5A-SCN10A demonstrate that genetic polymorphisms modulating cardiac conduction 4-7 can also influence susceptibility to cardiac arrhythmia. The implication of association with HEY2, supported by new evidence that Hey2 regulates cardiac electrical activity, shows that Brugada syndrome may originate from altered transcriptional programming during cardiac development 8. Altogether, our findings indicate that common genetic variation can have a strong impact on the predisposition to rare diseases. Sudden cardiac death (SCD) is a leading cause of mortality in Western countries, with an incidence close to 1 per 1,000 individuals per year 9. SCD results most frequently from ventricular fibrillation in the setting of coronary artery disease 10. In 5-10% of cases, however, SCD occurs owing to rare inherited cardiac arrhythmias, which are typically associated with a distinctive electrocardiogram (ECG) pattern in the absence of identifiable

Research paper thumbnail of Spectrum and Prevalence of Mutations Involving BrS1- Through BrS12-Susceptibility Genes in a Cohort of Unrelated Patients Referred for Brugada Syndrome Genetic Testing

Journal of the American College of Cardiology, 2012

The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada s... more The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada syndrome (BrS)-susceptibility genes discovered to date in a single large cohort of unrelated BrS patients. Background BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type STsegment elevation in the right precordial leads (V 1 to V 3 ; type 1 Brugada electrocardiographic [ECG] pattern) and the presence of a personal/family history of cardiac events. Methods Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing, comprehensive mutational analysis of BrS1-through BrS12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS (46 with clinically diagnosed BrS [ECG pattern plus personal/family history of a cardiac event] and 83 with a type 1 BrS ECG pattern only). Results Overall, 27 patients (21%) had a putative pathogenic mutation, absent in 1,400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 with a CACNB2B mutation, and 1 each with a KCNJ8 mutation, a KCND3 mutation, an SCN1Bb mutation, and an HCN4 mutation. The overall mutation yield was 23% in the type 1 BrS ECG pattern-only patients versus 17% in the clinically diagnosed BrS patients and was significantly greater among young men Ͻ20 years of age with clinically diagnosed BrS and among patients who had a prolonged PQ interval. Conclusions We identified putative pathogenic mutations in ϳ20% of our BrS cohort, with BrS genes 2 through 12 accounting for Ͻ5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200 ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.

Research paper thumbnail of A comprehensive electrocardiographic, molecular, and echocardiographic study of Brugada syndrome: Validation of the 2013 diagnostic criteria

Heart Rhythm, 2014

BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number... more BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number of diagnostic leads in Brugada syndrome (BrS) has been settled by a recent expert consensus statement. OBJECTIVE To test the validity of the new electrocardiographic (ECG) diagnostic criteria using echocardiographic, molecular, and clinical evidence in 1 clinical study population with BrS Q5. METHODS We analyzed 114 patients with BrS and with a spontaneous or drug-induced type 1 ECG pattern recorded in 1 or more right precordial leads in fourth, third, and second ICSs. The right ventricular outflow tract (RVOT) was localized by using echocardiography. All probands were screened on the SCN5A gene. RESULTS The percentage of mutation carriers (MCs) and the event rate were similar regardless of the diagnostic ICS (fourth vs high ICSs: MCs 23% vs 19%; event rate 22% vs 28%) and the number of diagnostic leads (1 vs Z2: MCs 20% vs 22%; event rate 22% vs 27%). The concordance between RVOT anatomical location and the diagnostic ICSs was 86%. The percentage of the diagnostic ECG pattern recorded was significantly increased by the exploration of the ICSs showing RVOT at echocardiography Q6 (echocardiography-guided approach vs conventional approach 100% vs 43%; P o .001). CONCLUSION The high ICSs are not inferior to the standard fourth ICS for the ECG diagnosis of BrS, and the interindividual variability depends on the anatomical location of the RVOT as assessed by using echocardiography. This approach significantly increases diagnostic sensitivity without decreasing specificity and fully supports the recently published new diagnostic criteria.

Research paper thumbnail of FGF12 is a candidate Brugada syndrome locus

Heart Rhythm, 2013

BACKGROUND-Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause.... more BACKGROUND-Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause. Of the known BrS-susceptibility genes, loss-of-function mutations in SCN5A or CACNA1C and their auxiliary subunits are most common. On the basis of the recent demonstration that fibroblast growth factor (FGF) homologous factors (FHFs; FGF11-FGF14) regulate cardiac Na + and Ca 2+ channel currents, we hypothesized that FHFs are candidate BrS loci. OBJECTIVE-The goal of this study was to test whether FGF12 is a candidate BrS locus. METHODS-We used quantitative polymerase chain reaction to identify the major FHF expressed in the human ventricle and then queried a phenotype-positive, genotype-negative BrS biorepository for FHF mutations associated with BrS. We queried the effects of an identified mutant with biochemical analyses combined with electrophysiological assessment in a novel rat

Research paper thumbnail of Characterization of SEMA3A-encoded semaphorin as a naturally occurring Kv4.3 protein inhibitor and its contribution to Brugada syndrome

Circulation research, 2014

Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in ... more Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in the nervous and cardiac systems. In addition, SEMA3A has an amino acid motif that is analogous to hanatoxin, an inhibitor of voltage-gated K(+) channels. SEMA3A-knockout mice exhibit an abnormal ECG pattern and are prone to ventricular arrhythmias and sudden cardiac death. Our aim was to determine whether SEMA3A is a naturally occurring protein inhibitor of Kv4.3 (Ito) channels and its potential contribution to Brugada syndrome. Kv4.3, Nav1.5, Cav1.2, or Kv4.2 were coexpressed or perfused with SEMA3A in HEK293 cells, and electrophysiological properties were examined via whole-cell patch clamp technique. SEMA3A selectively altered Kv4.3 by significantly reducing peak current density without perturbing Kv4.3 cell surface protein expression. SEMA3A also reduced Ito current density in cardiomyocytes derived from human-induced pluripotent stem cells. Disruption of a putative toxin binding dom...

Research paper thumbnail of Role of common and rare variants in SCN10A: Results from the Brugada syndrome QRS locus gene discovery collaborative study

Cardiovascular research, Jan 17, 2015

Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac co... more Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration. A multi-centre study sequenced 7 candidate genes (SCN10A, HAND1, PLN, CASQ2, TKT, TBΧ3 and ΤΒΧ5) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A, were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for 4/7 probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A) showed co-segregation. Th...

Research paper thumbnail of Genotypes and haplotypes in the 3′ untranslated region of the HLA-G gene and their association with clinical outcome of hematopoietic stem cell transplantation for beta-thalassemia

Tissue Antigens, 2012

Polymorphisms in the 3 untranslated region (3 UTR) of HLA-G, an important player in immunological... more Polymorphisms in the 3 untranslated region (3 UTR) of HLA-G, an important player in immunological tolerance, could be involved in post-transcriptional expression control, and their association with different clinical immune-related conditions including autoimmunity and transplantation is of mounting interest. Most studies have focused on a 14 base pair (bp) insertion/deletion (ins/del), while additional singlenucleotide polymorphisms (SNPs) in the HLA-G 3 UTR have been described but not extensively investigated for their clinical relevance. Here we have comparatively studied the association between 3 UTR haplotypes of HLA-G, or the 14 bp ins/del, with clinical outcome of HLA-identical sibling hematopoietic stem cell transplantation (HSCT) in 147 Middle Eastern beta-thalassemia patients. Sequence based typing of 3 UTR HLA-G polymorphisms in the patients and in 102 healthy Italian blood donors showed strong linkage disequilibrium between the 14 bp ins/del and five 3 UTR SNPs, which together could be arranged into eight distinct haplotypes based on expectationmaximization studies, with four predominant haplotypes (UTRs1-4). After HSCT, we found a moderate though not significant association between the presence of UTR-2 in double dose and protection from acute graft versus host disease (hazard ratio (HR) 0.45, 95% confidence intervals (CI): 0.14-1.45; P = 0.18), an effect that was also seen when the corresponding 14 bp ins/ins genotype was considered alone (HR 0.42, 95% CI: 0.16-1.06; P = 0.07). No association was found with rejection or survival. Taken together, our data show that there is no apparent added value of considering entire 3 UTR HLA-G haplotypes for risk prediction after allogeneic HSCT for beta-thalassemia.

Research paper thumbnail of Common variants at SCN5A-SCN10A and HEY2 are associated with Brugada syndrome, a rare disease with high risk of sudden cardiac death

Nature Genetics, 2013

Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in ar... more Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in around 20% of cases. Through a genome-wide association study of 312 individuals with Brugada syndrome and 1,115 controls, we detected 2 significant association signals at the SCN10A locus (rs10428132) and near the HEY2 gene (rs9388451). Independent replication confirmed both signals (meta-analyses: rs10428132, P = 1.0 × 10(-68); rs9388451, P = 5.1 × 10(-17)) and identified one additional signal in SCN5A (at 3p21; rs11708996, P = 1.0 × 10(-14)). The cumulative effect of the three loci on disease susceptibility was unexpectedly large (Ptrend = 6.1 × 10(-81)). The association signals at SCN5A-SCN10A demonstrate that genetic polymorphisms modulating cardiac conduction can also influence susceptibility to cardiac arrhythmia. The implication of association with HEY2, supported by new evidence that Hey2 regulates cardiac electrical activity, shows that Brugada syndrome may originate from altered transcriptional programming during cardiac development. Altogether, our findings indicate that common genetic variation can have a strong impact on the predisposition to rare diseases.

Research paper thumbnail of Spectrum and Prevalence of Mutations Involving BrS1- Through BrS12-Susceptibility Genes in a Cohort of Unrelated Patients Referred for Brugada Syndrome Genetic Testing

Journal of the American College of Cardiology, 2012

The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada s... more The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada syndrome (BrS)-susceptibility genes discovered to date in a single large cohort of unrelated BrS patients. BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type ST-segment elevation in the right precordial leads (V1 to V3; type 1 Brugada electrocardiographic [ECG] pattern) and the presence of a personal/family history of cardiac events. Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing, comprehensive mutational analysis of BrS1- through BrS12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS (46 with clinically diagnosed BrS [ECG pattern plus personal/family history of a cardiac event] and 83 with a type 1 BrS ECG pattern only). Overall, 27 patients (21%) had a putative pathogenic mutation, absent in 1,400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 with a CACNB2B mutation, and 1 each with a KCNJ8 mutation, a KCND3 mutation, an SCN1Bb mutation, and an HCN4 mutation. The overall mutation yield was 23% in the type 1 BrS ECG pattern-only patients versus 17% in the clinically diagnosed BrS patients and was significantly greater among young men&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;20 years of age with clinically diagnosed BrS and among patients who had a prolonged PQ interval. We identified putative pathogenic mutations in ∼20% of our BrS cohort, with BrS genes 2 through 12 accounting for &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200 ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.

Research paper thumbnail of A comprehensive electrocardiographic, molecular and echocardiographic study of the Brugada Syndrome: validation of the 2013 diagnostic criteria

Heart Rhythm, 2014

. BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the numb... more . BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number of diagnostic leads in Brugada syndrome (BrS) has been settled by a recent expert consensus statement.

Research paper thumbnail of FGF12 is a candidate Brugada syndrome locus

Heart Rhythm, 2013

BACKGROUND Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause.... more BACKGROUND Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause. Of the known BrSsusceptibility genes, loss-of-function mutations in SCN5A or CACNA1C and their auxiliary subunits are most common. On the basis of the recent demonstration that fibroblast growth factor (FGF) homologous factors (FHFs; FGF11-FGF14) regulate cardiac Na þ and Ca 2þ channel currents, we hypothesized that FHFs are candidate BrS loci.

Research paper thumbnail of Characterization of SEMA3A-encoded semaphorin as a naturally occurring Kv4.3 protein inhibitor and its contribution to Brugada syndrome

Circulation research, 2014

Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in ... more Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in the nervous and cardiac systems. In addition, SEMA3A has an amino acid motif that is analogous to hanatoxin, an inhibitor of voltage-gated K(+) channels. SEMA3A-knockout mice exhibit an abnormal ECG pattern and are prone to ventricular arrhythmias and sudden cardiac death. Our aim was to determine whether SEMA3A is a naturally occurring protein inhibitor of Kv4.3 (Ito) channels and its potential contribution to Brugada syndrome. Kv4.3, Nav1.5, Cav1.2, or Kv4.2 were coexpressed or perfused with SEMA3A in HEK293 cells, and electrophysiological properties were examined via whole-cell patch clamp technique. SEMA3A selectively altered Kv4.3 by significantly reducing peak current density without perturbing Kv4.3 cell surface protein expression. SEMA3A also reduced Ito current density in cardiomyocytes derived from human-induced pluripotent stem cells. Disruption of a putative toxin binding dom...

Research paper thumbnail of Role of common and rare variants in SCN10A: Results from the Brugada syndrome QRS locus gene discovery collaborative study

Cardiovascular research, Jan 17, 2015

Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac co... more Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration. A multi-centre study sequenced 7 candidate genes (SCN10A, HAND1, PLN, CASQ2, TKT, TBΧ3 and ΤΒΧ5) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A, were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for 4/7 probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A) showed co-segregation. Th...

Research paper thumbnail of Common variants at SCN5A-SCN10A and HEY2 are associated with Brugada syndrome, a rare disease with high risk of sudden cardiac death

Nature Genetics, 2013

Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in ar... more Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in around 20% of cases 1-3. Through a genome-wide association study of 312 individuals with Brugada syndrome and 1,115 controls, we detected 2 significant association signals at the SCN10A locus (rs10428132) and near the HEY2 gene (rs9388451). Independent replication confirmed both signals (meta-analyses: rs10428132, P = 1.0 × 10 −68 ; rs9388451, P = 5.1 × 10 −17) and identified one additional signal in SCN5A (at 3p21; rs11708996, P = 1.0 × 10 −14). The cumulative effect of the three loci on disease susceptibility was unexpectedly large (P trend = 6.1 × 10 −81). The association signals at SCN5A-SCN10A demonstrate that genetic polymorphisms modulating cardiac conduction 4-7 can also influence susceptibility to cardiac arrhythmia. The implication of association with HEY2, supported by new evidence that Hey2 regulates cardiac electrical activity, shows that Brugada syndrome may originate from altered transcriptional programming during cardiac development 8. Altogether, our findings indicate that common genetic variation can have a strong impact on the predisposition to rare diseases. Sudden cardiac death (SCD) is a leading cause of mortality in Western countries, with an incidence close to 1 per 1,000 individuals per year 9. SCD results most frequently from ventricular fibrillation in the setting of coronary artery disease 10. In 5-10% of cases, however, SCD occurs owing to rare inherited cardiac arrhythmias, which are typically associated with a distinctive electrocardiogram (ECG) pattern in the absence of identifiable

Research paper thumbnail of Spectrum and Prevalence of Mutations Involving BrS1- Through BrS12-Susceptibility Genes in a Cohort of Unrelated Patients Referred for Brugada Syndrome Genetic Testing

Journal of the American College of Cardiology, 2012

The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada s... more The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada syndrome (BrS)-susceptibility genes discovered to date in a single large cohort of unrelated BrS patients. Background BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type STsegment elevation in the right precordial leads (V 1 to V 3 ; type 1 Brugada electrocardiographic [ECG] pattern) and the presence of a personal/family history of cardiac events. Methods Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing, comprehensive mutational analysis of BrS1-through BrS12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS (46 with clinically diagnosed BrS [ECG pattern plus personal/family history of a cardiac event] and 83 with a type 1 BrS ECG pattern only). Results Overall, 27 patients (21%) had a putative pathogenic mutation, absent in 1,400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 with a CACNB2B mutation, and 1 each with a KCNJ8 mutation, a KCND3 mutation, an SCN1Bb mutation, and an HCN4 mutation. The overall mutation yield was 23% in the type 1 BrS ECG pattern-only patients versus 17% in the clinically diagnosed BrS patients and was significantly greater among young men Ͻ20 years of age with clinically diagnosed BrS and among patients who had a prolonged PQ interval. Conclusions We identified putative pathogenic mutations in ϳ20% of our BrS cohort, with BrS genes 2 through 12 accounting for Ͻ5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200 ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.

Research paper thumbnail of A comprehensive electrocardiographic, molecular, and echocardiographic study of Brugada syndrome: Validation of the 2013 diagnostic criteria

Heart Rhythm, 2014

BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number... more BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number of diagnostic leads in Brugada syndrome (BrS) has been settled by a recent expert consensus statement. OBJECTIVE To test the validity of the new electrocardiographic (ECG) diagnostic criteria using echocardiographic, molecular, and clinical evidence in 1 clinical study population with BrS Q5. METHODS We analyzed 114 patients with BrS and with a spontaneous or drug-induced type 1 ECG pattern recorded in 1 or more right precordial leads in fourth, third, and second ICSs. The right ventricular outflow tract (RVOT) was localized by using echocardiography. All probands were screened on the SCN5A gene. RESULTS The percentage of mutation carriers (MCs) and the event rate were similar regardless of the diagnostic ICS (fourth vs high ICSs: MCs 23% vs 19%; event rate 22% vs 28%) and the number of diagnostic leads (1 vs Z2: MCs 20% vs 22%; event rate 22% vs 27%). The concordance between RVOT anatomical location and the diagnostic ICSs was 86%. The percentage of the diagnostic ECG pattern recorded was significantly increased by the exploration of the ICSs showing RVOT at echocardiography Q6 (echocardiography-guided approach vs conventional approach 100% vs 43%; P o .001). CONCLUSION The high ICSs are not inferior to the standard fourth ICS for the ECG diagnosis of BrS, and the interindividual variability depends on the anatomical location of the RVOT as assessed by using echocardiography. This approach significantly increases diagnostic sensitivity without decreasing specificity and fully supports the recently published new diagnostic criteria.

Research paper thumbnail of FGF12 is a candidate Brugada syndrome locus

Heart Rhythm, 2013

BACKGROUND-Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause.... more BACKGROUND-Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause. Of the known BrS-susceptibility genes, loss-of-function mutations in SCN5A or CACNA1C and their auxiliary subunits are most common. On the basis of the recent demonstration that fibroblast growth factor (FGF) homologous factors (FHFs; FGF11-FGF14) regulate cardiac Na + and Ca 2+ channel currents, we hypothesized that FHFs are candidate BrS loci. OBJECTIVE-The goal of this study was to test whether FGF12 is a candidate BrS locus. METHODS-We used quantitative polymerase chain reaction to identify the major FHF expressed in the human ventricle and then queried a phenotype-positive, genotype-negative BrS biorepository for FHF mutations associated with BrS. We queried the effects of an identified mutant with biochemical analyses combined with electrophysiological assessment in a novel rat

Research paper thumbnail of Characterization of SEMA3A-encoded semaphorin as a naturally occurring Kv4.3 protein inhibitor and its contribution to Brugada syndrome

Circulation research, 2014

Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in ... more Semaphorin 3A (SEMA3A)-encoded semaphorin is a chemorepellent that disrupts neural patterning in the nervous and cardiac systems. In addition, SEMA3A has an amino acid motif that is analogous to hanatoxin, an inhibitor of voltage-gated K(+) channels. SEMA3A-knockout mice exhibit an abnormal ECG pattern and are prone to ventricular arrhythmias and sudden cardiac death. Our aim was to determine whether SEMA3A is a naturally occurring protein inhibitor of Kv4.3 (Ito) channels and its potential contribution to Brugada syndrome. Kv4.3, Nav1.5, Cav1.2, or Kv4.2 were coexpressed or perfused with SEMA3A in HEK293 cells, and electrophysiological properties were examined via whole-cell patch clamp technique. SEMA3A selectively altered Kv4.3 by significantly reducing peak current density without perturbing Kv4.3 cell surface protein expression. SEMA3A also reduced Ito current density in cardiomyocytes derived from human-induced pluripotent stem cells. Disruption of a putative toxin binding dom...

Research paper thumbnail of Role of common and rare variants in SCN10A: Results from the Brugada syndrome QRS locus gene discovery collaborative study

Cardiovascular research, Jan 17, 2015

Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac co... more Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration. A multi-centre study sequenced 7 candidate genes (SCN10A, HAND1, PLN, CASQ2, TKT, TBΧ3 and ΤΒΧ5) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A, were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for 4/7 probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A) showed co-segregation. Th...

Research paper thumbnail of Genotypes and haplotypes in the 3′ untranslated region of the HLA-G gene and their association with clinical outcome of hematopoietic stem cell transplantation for beta-thalassemia

Tissue Antigens, 2012

Polymorphisms in the 3 untranslated region (3 UTR) of HLA-G, an important player in immunological... more Polymorphisms in the 3 untranslated region (3 UTR) of HLA-G, an important player in immunological tolerance, could be involved in post-transcriptional expression control, and their association with different clinical immune-related conditions including autoimmunity and transplantation is of mounting interest. Most studies have focused on a 14 base pair (bp) insertion/deletion (ins/del), while additional singlenucleotide polymorphisms (SNPs) in the HLA-G 3 UTR have been described but not extensively investigated for their clinical relevance. Here we have comparatively studied the association between 3 UTR haplotypes of HLA-G, or the 14 bp ins/del, with clinical outcome of HLA-identical sibling hematopoietic stem cell transplantation (HSCT) in 147 Middle Eastern beta-thalassemia patients. Sequence based typing of 3 UTR HLA-G polymorphisms in the patients and in 102 healthy Italian blood donors showed strong linkage disequilibrium between the 14 bp ins/del and five 3 UTR SNPs, which together could be arranged into eight distinct haplotypes based on expectationmaximization studies, with four predominant haplotypes (UTRs1-4). After HSCT, we found a moderate though not significant association between the presence of UTR-2 in double dose and protection from acute graft versus host disease (hazard ratio (HR) 0.45, 95% confidence intervals (CI): 0.14-1.45; P = 0.18), an effect that was also seen when the corresponding 14 bp ins/ins genotype was considered alone (HR 0.42, 95% CI: 0.16-1.06; P = 0.07). No association was found with rejection or survival. Taken together, our data show that there is no apparent added value of considering entire 3 UTR HLA-G haplotypes for risk prediction after allogeneic HSCT for beta-thalassemia.

Research paper thumbnail of Common variants at SCN5A-SCN10A and HEY2 are associated with Brugada syndrome, a rare disease with high risk of sudden cardiac death

Nature Genetics, 2013

Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in ar... more Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in around 20% of cases. Through a genome-wide association study of 312 individuals with Brugada syndrome and 1,115 controls, we detected 2 significant association signals at the SCN10A locus (rs10428132) and near the HEY2 gene (rs9388451). Independent replication confirmed both signals (meta-analyses: rs10428132, P = 1.0 × 10(-68); rs9388451, P = 5.1 × 10(-17)) and identified one additional signal in SCN5A (at 3p21; rs11708996, P = 1.0 × 10(-14)). The cumulative effect of the three loci on disease susceptibility was unexpectedly large (Ptrend = 6.1 × 10(-81)). The association signals at SCN5A-SCN10A demonstrate that genetic polymorphisms modulating cardiac conduction can also influence susceptibility to cardiac arrhythmia. The implication of association with HEY2, supported by new evidence that Hey2 regulates cardiac electrical activity, shows that Brugada syndrome may originate from altered transcriptional programming during cardiac development. Altogether, our findings indicate that common genetic variation can have a strong impact on the predisposition to rare diseases.

Research paper thumbnail of Spectrum and Prevalence of Mutations Involving BrS1- Through BrS12-Susceptibility Genes in a Cohort of Unrelated Patients Referred for Brugada Syndrome Genetic Testing

Journal of the American College of Cardiology, 2012

The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada s... more The aim of this study was to provide the spectrum and prevalence of mutations in the 12 Brugada syndrome (BrS)-susceptibility genes discovered to date in a single large cohort of unrelated BrS patients. BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type ST-segment elevation in the right precordial leads (V1 to V3; type 1 Brugada electrocardiographic [ECG] pattern) and the presence of a personal/family history of cardiac events. Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing, comprehensive mutational analysis of BrS1- through BrS12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS (46 with clinically diagnosed BrS [ECG pattern plus personal/family history of a cardiac event] and 83 with a type 1 BrS ECG pattern only). Overall, 27 patients (21%) had a putative pathogenic mutation, absent in 1,400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 with a CACNB2B mutation, and 1 each with a KCNJ8 mutation, a KCND3 mutation, an SCN1Bb mutation, and an HCN4 mutation. The overall mutation yield was 23% in the type 1 BrS ECG pattern-only patients versus 17% in the clinically diagnosed BrS patients and was significantly greater among young men&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;20 years of age with clinically diagnosed BrS and among patients who had a prolonged PQ interval. We identified putative pathogenic mutations in ∼20% of our BrS cohort, with BrS genes 2 through 12 accounting for &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200 ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.

Research paper thumbnail of A comprehensive electrocardiographic, molecular and echocardiographic study of the Brugada Syndrome: validation of the 2013 diagnostic criteria

Heart Rhythm, 2014

. BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the numb... more . BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number of diagnostic leads in Brugada syndrome (BrS) has been settled by a recent expert consensus statement.

Research paper thumbnail of FGF12 is a candidate Brugada syndrome locus

Heart Rhythm, 2013

BACKGROUND Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause.... more BACKGROUND Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause. Of the known BrSsusceptibility genes, loss-of-function mutations in SCN5A or CACNA1C and their auxiliary subunits are most common. On the basis of the recent demonstration that fibroblast growth factor (FGF) homologous factors (FHFs; FGF11-FGF14) regulate cardiac Na þ and Ca 2þ channel currents, we hypothesized that FHFs are candidate BrS loci.