These mutations include but are not limited to the SCN5A
, GPD1-L, CACNA1C, CACNB2, SCN1B, KCNE3, SCN3B, and HCN4genes (5).
In contrast, LQT3 (caused by gain of function variants in SCN5A
) may be treated with sodium channel blockers such as mexilitine, flecainide, or ranolazine (24).
On the other hand, SCN5A
R1193Q (amino acid substitution of glutamine for arginine), which was identified in this case, is a variant that alters the current of cardiac sodium channel .
mutations, the defect in sodium channels leads to decrease in the sodium current and a shortening of the cardiac action potential by blunting phase 0 depolarisation.
The analysis demonstrated that a defect in the SCN5A
gene was found in 2.2 percent of IBS patients.
To incorporate the effects of SCN5A
mutation and acetylcholine (Ach) into the models, (i) parameters of the [Na.sup.+] current were changed according to the study of Butters et al.
GPD1-L catalyses the conversion of sn-glycerol 3-phosphate to glycerone phosphate and binds to the SCN5A
ion channel protein; mutations in the GPD1L gene have been linked to Brugada syndrome and to sudden infant death syndrome .
le Coq et al., "Novel Brugada SCN5A
mutation leading to ST segment elevation in the inferior or the right precordial leads," Journal of Cardiovascular Electrophysiology, vol.
In the case at hand, the child had mutation in the SCN5A
gene, which encodes a sodium channel, and a common polymorphism in the KCNH2 gene, which encodes a potassium channel.
In approximately one fourth of Brugada patients, a mutation has been reported in the cardiac sodium channel gene (SCN5A
) on chromosome 3, which encodes for the a-subunit of the cardiac sodium channel (2).
(6) Mutation in the [Na.sup.+] channel gene SCN5A
, on chromosome 3 results in LQT3 (about 8-10% of cases).