Novel mutation (H402R) in the S1 domain of KCNH2-encoded gene associated with long QT syndrome in a Spanish family.

Long-QT syndrome is a congenital cardiac disease resulting in ventricular arrhythmias and sudden death. Genetic mutations in two protein ion-channel genes, KCNQ1 and KCNH2. The mutations position in these genes provides additional information about the evaluation of the risk-stratification. In a Spanish family in whom previous repetitive syncope episodes, sudden death and pathological prolongation of the QT interval were documented, a novel heterozygous mutation in the KCNH2 gene (A1218>G) was identified. This mutation loading to amino acid substitution H420R in the S1 transmembrane domain of KCNH2. The new A1218>G mutation in the KCNH2 gene detected in this Spanish family causes arrhythmia manifestation in the carriers.