KCNE1 and familial long QT syndrome: While the majority of the Swedish p.R518X JLNS and LQTS probands have now been identified as pertaining to a founder population, the additional finding of two p.R518X probands, as well as one parent to a homozygous p.R518X case, lacking the founder haplotype supports the occurrence of p.R518X also as a hotspot mutation in the Swedish setting.