General Information of Drug Transporter (DT)
DT ID	DTD0527 Transporter Info
Gene Name	SCN4A
Protein Name	Voltage-gated sodium channel alpha Nav1.4
Gene ID	6329
UniProt ID	P35499
Genetic Polymorphisms of DT (GPD)
Genetic Polymorphism	rs80338792
Site of GPD	chr17:63943846 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	C>A / C>G / C>T
Minor Allele Frequency	G=0.0000/1 (Global)
Allele T	Click to Show/Hide the Full List of Affected Drugs:           8 Drugs in Total
Flecainide	Drug Info	Myotonia	Correlated with the increased drug response in patients (compare with allele C)		[ 1]
Mexiletine	N.A.	Death	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele C.		[ 2]
Flecainide	N.A.	Death	Allele T is not associated with inhibition of SCN4A with flecainide as compared to allele C.		[ 2]
Flecainide	N.A.	Death	Allele T is associated with increased response to flecainide in people with Myotonia as compared to allele C.		[ 1]
Flecainide	N.A.	Myotonia	Allele T is associated with increased response to flecainide in people with Myotonia as compared to allele C.		[ 1]
Mexiletine	N.A.	Myotonia	Allele T is associated with increased response to flecainide in people with Myotonia as compared to allele C.		[ 1]
Flecainide	N.A.	Myotonia	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele C.		[ 2]
Mexiletine	N.A.	Myotonia	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele C.		[ 2]
Genotype CC	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonia	Patients with the CC genotype may have similar response to treatment with flecainide as to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Mexiletine	N.A.	Myotonia	Patients with the CC genotype may have similar response to treatment with flecainide as to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Genotype CT	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonia	Patients with the CT genotype may respond better to treatment with flecainide than to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Mexiletine	N.A.	Myotonia	Patients with the CT genotype may respond better to treatment with flecainide than to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Genotype TT	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonia	Patients with the TT genotype may respond better to treatment with flecainide than to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Mexiletine	N.A.	Myotonia	Patients with the TT genotype may respond better to treatment with flecainide than to treatment with mexiletine. Other genetic and clinical factors may also influence a patient's response to treatment.		[ 1]
Genetic Polymorphism	rs886043595
Site of GPD	chr17:63944692 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	A>C / A>G
Allele C	Click to Show/Hide the Full List of Affected Drugs:           3 Drugs in Total
Flecainide	N.A.	Death	Allele C is not associated with inhibition of SCN4A with flecainide as compared to allele A.		[ 2]
Mexiletine	N.A.	Death	Allele C is associated with decreased inhibition of SCN4A with mexiletine as compared to allele A.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Allele C is associated with decreased inhibition of SCN4A with mexiletine as compared to allele A.		[ 2]
Genotype AA	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the AA genotype may have an increased response to mexiletine as compared to patients with the AC or CC genotypes. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype AC	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the AC genotype may have a decreased response to mexiletine as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype CC	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the CC genotype may have a decreased response to mexiletine as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genetic Polymorphism	rs121908551
Site of GPD	chr17:63944708 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	C>T
Allele T	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Death	Allele T is not associated with inhibition of SCN4A with mexiletine as compared to allele C.		[ 2]
Genetic Polymorphism	rs1567817380
Site of GPD	chr17:63943834 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	A>T
Allele T	Click to Show/Hide the Full List of Affected Drugs:           4 Drugs in Total
Mexiletine	N.A.	Death	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele A.		[ 2]
Flecainide	N.A.	Death	Allele T is associated with increased inhibition of SCN4A with flecainide as compared to allele A.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele A.		[ 2]
Flecainide	N.A.	Myotonic Disorders	Allele T is associated with increased inhibition of SCN4A with flecainide as compared to allele A.		[ 2]
Genotype AA	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the AA genotype may have an increased response to mexiletine as compared to patients with the AT or TT genotypes. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Flecainide	N.A.	Myotonic Disorders	Patients with the AA genotype may have a decreased response to flecainide as compared to patients with the AT or TT genotypes. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Genotype AT	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the AT genotype may have a decreased response to mexiletine as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Flecainide	N.A.	Myotonic Disorders	Patients with the AT genotype may have an increased response to flecainide as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Genotype TT	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the TT genotype may have a decreased response to mexiletine as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Flecainide	N.A.	Myotonic Disorders	Patients with the TT genotype may have an increased response to flecainide as compared to patients with the AA genotype. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Genetic Polymorphism	rs121908547
Site of GPD	chr17:63943825 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	G>A
Allele A	Click to Show/Hide the Full List of Affected Drugs:           5 Drugs in Total
Propafenone	N.A.	Death	Allele A is not associated with inhibition of SCN4A with propafenone as compared to allele G.		[ 2]
Mexiletine	N.A.	Death	Allele A is associated with decreased inhibition of SCN4A with mexiletine as compared to allele G.		[ 2]
Flecainide	N.A.	Death	Allele A is associated with increased inhibition of SCN4A with flecainide as compared to allele G.		[ 2]
Flecainide	N.A.	Myotonic Disorders	Allele A is associated with increased inhibition of SCN4A with flecainide as compared to allele G.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Allele A is associated with decreased inhibition of SCN4A with mexiletine as compared to allele G.		[ 2]
Genotype AA	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonic Disorders	Patients with the AA genotype may have an increased response to flecainide as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Patients with the AA genotype may have a decreased response to mexiletine as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype AG	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonic Disorders	Patients with the AG genotype may have an increased response to flecainide as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Patients with the AG genotype may have a decreased response to mexiletine as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype GG	Click to Show/Hide the Full List of Affected Drugs:           2 Drugs in Total
Flecainide	N.A.	Myotonic Disorders	Patients with the GG genotype may have a decreased response to flecainide as compared to patients with the AA or AG genotypes. Other genetic and clinical factors may also affect a patient's response to flecainide.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Patients with the GG genotype may have an increased response to mexiletine as compared to patients with the AA or AG genotypes. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genetic Polymorphism	rs121908560
Site of GPD	chr17:63944694 (GRCh38.p12)
GPD Type	SNP
Allele(s) in dbSNP	G>T
Allele T	Click to Show/Hide the Full List of Affected Drugs:           3 Drugs in Total
Flecainide	N.A.	Death	Allele T is not associated with inhibition of SCN4A with flecainide as compared to allele G.		[ 2]
Mexiletine	N.A.	Death	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele G.		[ 2]
Mexiletine	N.A.	Myotonic Disorders	Allele T is associated with decreased inhibition of SCN4A with mexiletine as compared to allele G.		[ 2]
Genotype GG	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the GG genotype may have an increased response to mexiletine as compared to patients with the GT or TT genotypes. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype GT	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the GT genotype may have a decreased response to mexiletine as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
Genotype TT	Click to Show/Hide the Full List of Affected Drugs:           1 Drugs in Total
Mexiletine	N.A.	Myotonic Disorders	Patients with the TT genotype may have a decreased response to mexiletine as compared to patients with the GG genotype. Other genetic and clinical factors may also affect a patient's response to mexiletine.		[ 2]
References
1	Dramatic improvement of myotonia permanens with flecainide: a two-case report of a possible bench-to-bedside pharmacogenetics strategy. Eur J Clin Pharmacol. 2013 Apr;69(4):1037-9.
2	Pharmacogenetics of myotonic hNav1.4 sodium channel variants situated near the fast inactivation gate. Pharmacol Res. 2019 Mar;141:224-235.

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