Abstract: RNA-guided programmable cytosine and adenine base editors are a powerful class of genome editing tool for the introduction of localized base transitions without generating a double-stranded DNA break. Base editors (BE) have an optimal window of activity relative to the PAM recognized by the Cas9 enzyme and these constructs are strand selective. Here we demonstrate that fusion of a programmable DNA-binding domain (pDBD) or another Cas9 orthologue to spCas9-BE, we can produce an RNA-programmable Cas9-BE-pDBD chimera or Cas9-BE-Cas9 chimeras with dramatically improved activities and increased targeting range. Cas9-pDBD or Cas9-Cas9 fusion base editors display an expanded targeting repertoire and achieve highly specific genome editing, which can be tailored to achieve extremely precise genome editing at nearly any genomic locus.

Abstract: Provided herein are ribonucleoprotein (RNP) complexes comprising a DNA-targeting endonuclease Cas (CRISPR-associated) protein and a guide RNA (gRNA) that that targets and hybridizes to the ?-Globin gene. In one embodiment, the Cas protein is Cas9 and the gRNA comprises the sequence of SEQ ID NO: 1. In one embodiment, the Cas protein is Cas12a and the gRNA comprises the sequence of SEQ ID NO: 3.

Abstract: Provided herein are methods and compositions for increasing fetal hemoglobin levels in a cell by disrupting BCL11A expression at the genomic level. Also provided herein are methods and compositions relating to the treatment of hemoglobinopathies by reinduction of fetal hemoglobin levels.