The current Curators' Favorite Papers are about rare variants, which are part of the genetic diversity within and among populations. Keinan and Clark explain how the recent explosive human population growth has resulted in an excess of rare genetic variants [PMID: 22582263]. The article by Nelson et al. focuses on rare functional variants in drug target genes [PMID: 22604722]. Ramirez et al. concluded that novel rare non-synonymous variants in congenital cardiac arrhythmia genes are frequent in drug-induced torsades de pointes [PMID: 22584458].