Project description:Donated human MII oocytes and zygotes were injected with ABE mRNA or RNP, or Cas9 RNP targeting indicated genes. The purpose of the experiment is to study DNA repair after base editing in preimplantation human embryos. Key findings are a lack of chromosomal aneuploidies in base editing samples, contrasting with the outcomes after Cas9 cleavage at the same sites. Off target base editing is highly gRNA dependent. Base editing is efficient, and lacks the genotoxicity of Cas9.
Project description:Even the latest generation of base editor (BE3) causes unwanted indels and non-C-to-T substitutions, compromising the fidelity of base editing outcome. Here we report a enhanced base editing system. The enhanced base edting system decreased the formation of unintended indels and C-to-A/C-to-G substitutions, and increased the frequency of desired C-to-T substitution, thereby improving both the accuracy and efficiency of base editing.
Project description:The goal of these experiments were to test the on-target and target-adjacent editing efficiencies of different single-nucleobase editing systems. Previous studies have shown that tethering DNA mutating enzymes to Cas9-nickase-UGI complexes results in editing of chromosomal DNA. However, these editing events encompass undesirable target-adjacent nucleobase edits. Here, we characterize a novel approach that reduces the frequency of target-adjacent editing while maintaining a high level of on-target editing.