NOS1AP and familial long QT syndrome: It should be noted in this context that relatively common genetic variants in other genes (eg, NOS1AP), not known to be single-gene causes of LQTS, have been described as having a mild impact on ionic currents and have been associated with mild QT prolongation in population studies and with severity of phenotype in LQTS.48,49 Curation of such risk alleles or polygenic risk scores was not part of this ClinGen Working Group’s mandate, requires a different analytical process, and are not included in this study.