Base Editor Nucleobase Substitution for Sickle Cell Disease
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Solution Overview
Problem
Current genome editing technologies, such as CRISPR, are inefficient in correcting point mutations and often introduce random insertions or deletions (indels) at the target locus, which can lead to unintended consequences in genetic diseases.
Innovation Solution
A programmable base editor system comprising a polynucleotide-programmable nucleotide-binding domain and a deaminase domain is used to target and edit specific nucleobases, allowing precise substitution of pathogenic amino acids with benign ones, such as changing valine to alanine in the β-globin protein to treat sickle cell disease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CRISPR genome editing technology is used to correct point mutations, then gene correction can be achieved, but random insertions or deletions (indels) are introduced at the target locus
Solution Approach 1:
The patent extracts and removes the harmful double-stranded DNA break step from the CRISPR editing process. By using base editors that directly convert one nucleotide base to another without creating dsDNA breaks, the technology eliminates the source of random indels while maintaining the ability to correct point mutations with high precision.
Solution Approach 2:
The patent changes the fundamental mechanism of genome editing from a break-based approach to a direct base conversion approach. Base editors use deaminase enzymes to chemically convert specific bases (e.g., C to T, A to G) at targeted locations, fundamentally altering the editing parameter from structural disruption to chemical modification, thereby achieving precise point mutation correction without indels.
2Manufacturing precision
If double-stranded DNA breaks are introduced for gene correction, then point mutation correction can be attempted, but cellular DNA repair processes result in random insertions or deletions (indels)
Solution Approach 1:
The patent converts the harmful effect of cellular DNA repair mechanisms (which cause random indels) into a beneficial process. By using base editors that create only single-base modifications without dsDNA breaks, the technology directs cellular repair processes toward accurate base substitution rather than error-prone indel formation, effectively converting the repair mechanism from a source of harm to a tool for precise correction.
3Productivity
If current CRISPR approaches are used for point mutation correction, then some gene correction can be achieved, but the efficiency is low and undesired products are generated
Solution Approach 1:
The patent introduces base editors as intermediary molecules that mediate between the guide RNA targeting system and the final base substitution outcome. These base editors contain fused domains including a Cas protein for targeting, a deaminase for base conversion, and often a uracil glycosylase inhibitor to prevent repair of unwanted intermediates, thereby increasing efficiency while minimizing undesired products through controlled intermediate states.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves precise correction of genetic disorders by minimizing indels and translocations, effectively treating conditions like sickle cell disease by generating a β-globin protein variant that does not polymerize, thus alleviating the sickle cell phenotype.
Implementation Method 1
editing a nucleobase of the target nucleotide sequence by deaminating the nucleobase upon targeting of the base editor to the target nucleotide sequence, thereby treating the genetic disorder by changing the nucleobase to another nucleobase
Data Source
AI summary
Provided herein are compositions and methods of using base editors comprising a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain in conjunction with a guide polynucleotide. Also provided herein are base editor systems for editing nucleobases of target nucleotide sequences.