Whole-genome sequencing (WGS) is the most comprehensive genetic test possible, theoretically allowing the detection of all types of genetic variants. With decreasing DNA sequencing costs, we can now consider applying WGS to worldwide populations, but this requires the collection of DNA samples. While blood is the traditional source of DNA, saliva and buccal (cheek) samples are less invasive to collect and easier to ship. We compared the accuracy of WGS from blood, saliva, and buccal sources, and showed that while blood samples are best, saliva and buccal samples are nearly as good, and thus can be used for population-scale WGS. (By Dr. Brett Trost, https://jmg.bmj.com/content/early/2019/09/11/jmedgenet-2019-106281 )