Order of authorship in the original publication: Gaudelli, Komor, Rees....Liu. 

Liu and colleagues developed an advanced CRISPR system that can edit pairings of DNA nucleotide bases Adenine and Thymine into Guanine and Cytosine. In order to achieve this they created a new enzyme in the lab to chemically convert and work on the above pairings. They called this enzyme a "base editor."  In theory this tool would enable this improved CRISPR able to target a substantial fraction of SNPs (Single-nucleotide polymorphisms) associated with human genetic diseases.

(Thanks to Juan Weiss for this reference and its interpretation.)

Order of authorship in the original publication: Anzalone, Randolph, Davis....Liu.

Liu and colleagues modified the CRISPR tool to create the "prime editing" or precise genome editing technique. Working with human and mouse cells, the authors used a heavily modified Cas9 protein and the guide RNA. The new guide called "pegRNA" contains an RNA template with a reverse transcriptase which makes DNA for a new "desired/normal" DNA sequence from and on the blueprint carried in the pegRNA that is added to the genome at the abnormal / target location. With this new tool they performed 175 different edits, and as proof of principle, they created and then corrected the mutations that cause sicle cell anemia and Tay Sachs.

(Thanks to Juan Weiss for this reference and its interpretation.)

Using the base editor enzyme developed by Liu (GM11865), the authors report that they can “correct the pathogenic HGPS mutation in cultured fibroblasts derived from children with progeria and in a mouse model of HGPS.” Their technique resulted in “87-91% correction of the pathogenic allele, mitigation of the resulting RNA mis-splicing, reduced levels of progerin and correction of the nuclear abnormalities.” Mice treated like this, exhibited “improved vitality and greatly extended median lifespan from 215 to 510 days.” At the end they added that “these findings demonstrate the potential of in vivo base editing as a possible treatment for HGPS and other genetic diseases by directly correcting their root cause.”

Digital facsimile from PubMedCentral at this link. Order of authorship in the original publication: Koblan, Erdos, Wilson....Collins..Liu.

(Thanks to Juan Weiss for this reference and its interpretation.)