The first association testing regarding NOS1AP variants in LQTS patients was performed in carriers of the KCNQ1 A341V pathogenic variant (n = 205) from a South African founder population, reporting a significant association between variants rs4657139 and rs16847548 and the probability of having a QTc in the top 40% (rs4657139, p = 0.03; rs16847548, p = 0.03) [13]. This evidence concerns the gene NOS1AP and familial long QT syndrome.