Fortunately, advances in sequencing technology now provide an opportunity to address the role of rare SNVs. In recent years, the cost of direct DNA sequencing has dropped dramatically and technologic advances have facilitated the development of “high-throughput” sequencing.122,123 To date, these “next generation sequencing technologies” have been largely applied to study variants in exons, which are the protein-coding regions of the genome collectively known as the “exome.” Exons comprise about 30 megabases of DNA or 1% of the total genome. Although no exome-sequencing studies of depression have been reported at the time of this writing, such studies are underway. Next generation sequencing technologies can also be applied to the entire genome (“whole genome sequencing”), enabling researchers to explore a full range of genetic variants in both coding as well as non-coding regions of the genome.
