KCNE1 and familial long QT syndrome: Indeed, Roberts et al reached similar conclusions in their analysis of KCNE2, finding no evidence for a LQTS phenotype in the absence of other QT-prolonging factors in patients carrying rare or uncommon variants in this gene.31 One possible exception is evidence from several case reports suggesting an association between rare variants in KCNE1 and autosomal-recessive Jervell and Lange-Nielsen syndrome.28–30 In such rare cases, homozygous or compound heterozygous rare KCNE1 variants should be evaluated carefully for disease causality.