Jervell and Lange-Nielsen syndrome with novel KCNQ1 and additional gene mutations.

We encountered a boy with Jervell and Lange-Nielsen syndrome (JLNS) with compound heterozygous KCNQ1 mutations, maternal Trp248Phe and a novel paternal mutation, Leu347Arg. His father showed long QT (LQT) and arrhythmia. His mother was asymptomatic with no ECG abnormalities. The proband and his father had an additional mutation (SNTA1 Thr372Met), which is reportedly related to SIDS. These results suggest that multiple gene mutations influence the phenotype of KCNQ1 mutation-related arrhythmia.