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Whole Genome Sequencing

WHAT IT IS

Whole genome sequencing (WGS) is a comprehensive method that can rapidly sequence large amounts of DNA and provide genetic analysis of an individual's entire genome, including coding and non-coding regions of nuclear DNA. In the current study, the researchers used this technique to study the genome of single cells.

HOW IT WORKS

The scientists start with neuronal nuclei from postmortem brain. They individually sort single nuclei into wells on a microtiter plate. Then, then they amplify the entire genome from a single DNA copy using a highly efficient DNA polymerase that makes millions of copies of the original genome. They generate a tube of DNA as if it came from the blood of an individual, but it is obtained from a single cell's genomes. Then, they sequence that DNA sample from the single cell. The sequences are then mapped to the consensus genome and the variants that pop up in the sequencer that are different from the genome reference are annotated.

HOW IT IS APPLIED

WGS has been used mostly as a research tool to identify inherited disorders, mutations, and large and small variants that put people at risk for disease. More recently, costs for WGS have dropped substantially: It cost $350,000 in 2005 and today it can cost a few thousand dollars. It is being used clinically to diagnose disorders.