Realizing the full potential of gene editing

Harnessing the power of precise DNA repair

Our UltraHDR platform is a novel gene-editing technology designed to allow us to move CRISPR-based gene editing beyond cutting and gene disruption towards precise DNA repair, also known as homology directed repair (HDR). With our platform, we seek to harness the power of the cell’s natural DNA repair processes at high efficiencies to restore function to mutated genes that cause disease. This proprietary technology has the potential to go beyond personalized medicine and deliver individualized therapies with the ability to cure a patient of their genetic disease.

We are initially focused on developing one-time, stem cell-based cures for serious genetic diseases, like sickle cell disease and beta-thalassemia. However, our novel gene editing platform has been observed to be highly efficient across a wide range of cell types, yielding broad potential to treat cancer, autoimmune diseases, and neurodegenerative diseases.

Our UltraHDR platform: A ‘find and replace’ approach to gene editing

  1. Find the mutated gene

    First, we identify the genetic mutation that causes a specific disease, just like an editing software would find a misspelled word or incorrect sentence.

  2. Cut the incorrect DNA sequence

    Then, we use our proprietary HiFi Cas9, bound by a guide RNA, to make a highly precise cut to remove the incorrect DNA sequence in the disease-causing gene. Our HiFi Cas9 is specifically engineered to have higher fidelity, leading to more efficient and precise cutting at the target site.

  3. Replace with the correct DNA sequence

    Finally, we deliver a template containing the correct DNA sequence, aiming to restore and normalize function in the disease-causing gene, effectively rewriting a patient’s DNA so they can write the next chapter in their life story.

Our ‘find and replace’ approach to gene editing allows us to correct, replace, and insert genes anywhere in the genome.

Gene correction

Correct point mutations or short DNA stretches in endogenous locus.

Gene replacement

Replace gene driven by own promoter.

Targeted gene insertion

Knock-in promoter gene expression cassette into safe harbor location.

The science behind our gene editing platform

See how we’re using our UltraHDR platform to develop what we believe may be a definitive cure for sickle cell disease, and how this same approach is being used to develop potential cures for other diseases thought to be incurable.


Our vision is a future where the word ‘incurable’ no longer exists—transforming our founders’ groundbreaking discoveries into potential cures. Graphite Bio’s scientific approach is supported by extensive peer-reviewed preclinical research. Explore select publications featuring our novel UltraHDR platform below.

Our pursuit of ‘one dose, one cure’

We’re striving to create a future where the word ‘incurable’ no longer exists. The potential cures we’re developing are just the beginning of our work.

See what we’re developing