In the early 1990s, scientists found that they could engineer zinc-finger nucleases (ZFNs) to modify DNA sequences. ZFNs consist of zinc-finger proteins that find specific DNA sequences and enzymes known as nucleases, which cut DNA. Engineering ZFNs wasn't easy but it was the only game in town for gene editing.
Why CRISPR Matters
Scientists had known for several years that some bacteria used CRISPR-Cas9 to slice the DNA of attacking viruses as a self-defense mechanism. By giving a Cas molecule instructions of where to cut DNA through the help of a guide RNA molecule (gRNA), CRISPR has the power to disable any gene it’s programmed to find. CRISPR-based therapeutics could cure many genetic diseases by turning off a gene that wasn’t supposed to be on in the first place. CRISPR can also cut DNA, replace the break with a new segment, and correct a malfunctioning genetic mutation. The CRISPR-Cas9 system has generated a lot of excitement in the scientific community because it is faster, cheaper, more accurate, and more efficient than other existing genome editing methods.
In a landmark 2012 paper, Doudna, Charpentier, and Martin Jinek showed they could use this CRISPR/Cas9 system to cut up any genome at any place they wanted.
Further advances followed, Feng Zhang, a scientist at the Broad Institute in Boston, co-authored a paper in Science in February 2013 showing that CRISPR/Cas9 could be used to edit the genomes of cultured mouse cells or human cells. In the same issue of Science, Harvard’s George Church and his team showed how a different CRISPR technique could be used to edit human cells.
Who is leading in CRISPR technology?
The three leading gene-editing companies looking at commercialising CRISPR-based therapeutics are CRISPR Therapeutics, Intellia Therapeutics, and Editas Medicine.
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