Contributed equally
Brugada syndrome (BrS) is a rare, inherited arrhythmia syndrome. The most well-known gene that is responsible for causing BrS is
Brugada syndrome (BrS) is a rare, inheritable arrhythmia syndrome, which is characterized by a coved-type ST-segment elevation in the right precordial leads (V1 to V3) on surface electrocardiography (ECG) and a high incidence of sudden mortality in patients without evident structural heart disease, electrolyte disturbances or ischemia (
Since it was first reported by Chen
In the present study, a novel heterozygous mutation, A1428S, was identified in the
The study participants were identified and enrolled at Huazhong University of Science and Technology Union Hospital (Wuhan, China). Informed consent was obtained from the participants in accordance with the study protocols approved by the Ethics Committee of Huazhong University of Science and Technology. Twenty-eight family members, including 14 males and 14 females were involved in this study (
As described previously (
Mutation c.4282G>T (p.A1428S) disrupts an
Human embryonic kidney 293 (HEK293T) cells were purchased from the American Type Culture Collection (Manassas, VA, USA). These cells were cultured in Dulbecco's modified Eagle's medium (Sigma-Aldrich, St. Louis, MO, USA) containing 10% fetal bovine serum (Life Technologies, Paisley, UK), 2 mM L-glutamine, 100 U/ml penicillin G and 10 mg/ml streptomycin (Gibco-BRL, Burlington, ON, Canada) at 37°C in a humidified atmosphere containing 5% CO2. Cells were plated on poly-L-lysine-coated glass cover slips (12 mm) (Carl Zeiss, Inc., Oberkochen, Germany) and transiently transfected with wild-type (WT)
Macroscopic sodium currents from the transfected cells were recorded at room temperature (21–24°C) using the whole-cell patch clamp technique and an Axopatch 200B amplifier (Axon Instruments, Foster City, CA, USA). The extracellular solution contained: 70 mM NaCl, 80 mM CsCl, 5.4 mM KCl, 2 mM CaCl2, 1 mM MgCl2, 10 mM D-glucose and 10 mM HEPES (adjusted with CsOH to pH 7.3). The patch pipettes were fabricated from borosilicate glass capillaries (outer diameter, 1.5 mm; inner diameter, 1 mm; VitalSense Scientific Instruments, Wuhan, China) using a Sutter Model P-97 horizontal puller (Sutter Instrument Company, Novato, CA, USA). This typically had a resistance of 1–2 M when filled with the internal solution, which contained (in mM): 20 mM NaCl, 130 mM CsCl, 10 mM EGTA and 10 mM HEPES (adjusted to pH 7.2 with CsOH). Currents were amplified and filtered using an Axopatch 200B amplifier, and digitized with Digidata 1322A (Molecular Devices, Union City, CA, USA) at 5 kHz following analog filtering with the four-pole low-pass Bessel (2 kHz) of the amplifier. pCLAMP 9.0 and Origin 8.5 (OriginLab Corporation, Northampton, MA, USA) software were used for data acquisition and analysis, respectively. Series resistance compensation was used to improve the voltage-clamp control (70–80%). Peak current were normalized by the membrane capacitance and showed as the current density (pA/pF). Membrane conductance (G) was defined as
Results are presented as the mean ± standard error of the mean with sample sizes (n) indicating the number of cells from which the data were obtained. Statistical significance was assessed using the Student's t-test. P<0.05 was considered to indicate a statistically significant difference.
The proband, a 58-year-old patient (II3) was admitted to the emergency care unit due to syncope during walking with spontaneous recovery. A 12-lead ECG was performed without a drug challenge test and showed ST-segment elevation in the right precordial leads (
To identify the molecular basis of BrS in the proband, exons 1–28 of the dystrophin gene were amplified by PCR. By direct bidirectional sequencing of the PCR products in the proband, a heterozygous missense single nucleotide at position 4,282 (c.4282G>T) in exon 24 of the
Mutation c.4282G>T (p.A1428S) disrupts an
To understand the clinical phenotypes of this patient, the biophysical properties of the WT and MT channels were studied. The WT Nav1.5 channels and channels expressed from the mutated cDNAs of
The effects of the A1428S mutation on the Vm dependence of channel activation are shown in
In this study, a novel heterozygous mutation c.4282G>T in the
It is well known that the
The Nav1.5 channel α subunit consists of four homologous domains, and each domain contains six α-helical transmembrane repeats. In the present study, the substituted amino acid p.A1428S was located at the fifth α-helical transmembrane segment of domain III-S5/S6. Mutations located at this region have been previously reported, including N1380K (
In conclusion, to the best of our knowledge, this is the first description of a novel heterozygous missense mutation, A1428S, in exon 24 of the
This study was supported by grants from the National Natural Science Foundation of China (nos. 31301024 and 81400462) and the Natural Science Foundation of Hubei Province of China (no. 2012FKB02441).
Brugada syndrome
electrocardiography
human embryonic kidney 293 cells
mutation type
cardiac Na+ channel
polymerase chain reaction-restriction fragment length polymorphism
sudden cardiac death
wild-type
Pedigree chart of a family with Brugada syndrome. The affected family members are indicated by the filled symbols. The proband is indicated by an arrow (II3).
Representative bright-field and fluorescent images of HEK cells transfected with the
Diagnostic BrS ECG. Twelve-lead electrocardiogram showing a representative type 1 BrS ECG with coved ST-segment elevation in the right precordial leads, particularly in V2 and V3. The arrows indicate the coved ST-segment elevation. BrS, Brugada syndrome; ECG, electrocardiography.
Analysis the mutation of the
PCR-restriction fragment length polymorphism analysis of the mutation in exon 24 of the
Properties of sodium current recorded from HEK293T cells transfected with