Testing for rare variant associations in complex diseases.

The study of rare variants holds the promise of accounting for some of the missing heritability in complex traits. Next-generation sequencing technologies enable probing of variation across the full spectrum of allele frequencies. Multiple methods for the analysis of rare variants have been proposed and, recently, Ionita-Laza et al. have presented an approach with the theoretical capacity to detect risk and protective variants. The identification of rare risk variants could have major implications in understanding complex disease etiopathogenesis.