Whole genome sequencing (WGS) is the process of determining the entirety, or nearly the entirety, of the DNA sequence of an organism's genome at a single time.[2] This entails sequencing all of an organism's chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast. Whole genome sequencing has largely been used as a research tool, but was being introduced to clinics in 2014.[3][4][5] In the future of personalized medicine, whole genome sequence data may be an important tool to guide therapeutic intervention.[6] The tool of gene sequencing at SNP level is also used to pinpoint functional variants from association studies and improve the knowledge available to researchers interested in evolutionary biology, and hence may lay the foundation for predicting disease susceptibility and drug response.