SCN5A

(redirected from LQT3)

SCN5A

A gene on chromosome 3p21 that encodes an integral membrane protein and tetrodotoxin-resistant voltage-gated sodium channel alpha subunit, which is expressed primarily in cardiac myocytes and is responsible beginning the action potential as seen on an ECG/EKG.
 
Molecular pathology
SCN5A mutations are long QT syndrome type 3.
References in periodicals archive ?
Gene-specific response of dynamic ventricular repolarization to sympathetic stimulation in LQT1, LQT2 and LQT3 forms of congenital long QT syndrome.
LQT1 and LQT2 encode a rectifying potassium channel, while LQT3 encodes the alpha Sodium channel subunit.
Variants in 3 ion channel genes account for over 70% of patients with a definitive diagnosis of LQTS (13, 14) [although the yield is substantially less for all referral cases (15)]: loss of function variants in the potassium ion channel genes potassium voltage-gated channel subfamily Q member 1 (KCNQ1) and potassium voltage-gated channel subfamily H member 2 (KCNH2; LQT1 and LQT2 respectively) and gain of function variants in the sodium ion channel gene sodium voltage-gated channel alpha a subunit 5 (SCN5A; LQT3).
Antzelevitch, "Sodium channel block with mexiletine is effective in reducing dispersion of repolarization and preventing torsade de pointes in LQT2 and LQT3 models of the long-QT syndrome," Circulation, vol.
Here, we summarize the current effort to model "electrical human cardiac disease" caused by channelopathies finally leading to LQT-syndromes: LQT1, LQT2, LQT3, and LQT8 (Table 1).
(6) Mutation in the [Na.sup.+] channel gene SCN5A, on chromosome 3 results in LQT3 (about 8-10% of cases).
LQT3 genotype experience events during sleep or at rest.
Long QT and Jervelle Lange-Nielsen syndromes: Genetic defects and channel abnormalities Syndrome Gene Function Autosomal dominant LQT1 KCNQ1 [I.sub.ks] Decreased LQT2 KCNH2 [I.sub.Kr] Decreased LQT3 SCN5A [I.sub.Na] Decreased LQT4 ANK2 [I.sub.Na, K] Decreased LQT5 KCNE1 [I.sub.ks] Decreased LQT6 KCNE2 [I.sub.kr] Decreased LQT7 KCNJ2 [I.sub.k1] Decreased LQT8 CACNA1C [I.sub.Ca,L] Increased LQT9 CAV3 [I.sub.Na] Increased LQT10 SCN4B [I.sub.Na] Increased Autosomal recessive JLN1 KCNQ1 [I.sub.ks] Decreased JLN2 KCNE1 [I.sub.ks] Decreased Cardiac sodium ([I.sub.Na]), Potassium ([I.sub.ks], [I.sub.Kr], [I.sub.k1]) and Calcium currents
The majority of mutations have been identified in LQT1 (40%-55%), LQT2 (35%-45%), and LQT3 (2%-8%), which represent the genes KCNQ1, KCNH2, and SCN5A, respectively.
Sodium channel block with mexiletine is effective in reducing dispersion of repolarization and preventing torsade des pointes in LQT2 and LQT3 models of the long-QT syndrome.
The disorder is phenotypically quite similar to LQT3. In the largest LQT8 patient series studied to date--20 children followed for up to 12 years--all subjects presented with remarkably prolonged corrected QT intervals; the mean was 600 milliseconds.