The research represents the discovery and engineering of bridge recombinases, natural RNA-directed enzymes that enable programmable megabase-scale rearrangement of the human genome.[3][4] Scientists have developed a variant of ISCro4 (or IS622) that, after bridge RNA optimization and deep mutational scanning, achieved up to 20% efficiency of DNA insertion into the human genome and 82% specificity for target sites.[1][2][3][4] The system enables the simultaneous recognition of two different DNA targets via bridge RNA, facilitating coordinated operations such as insertion, excision, or reversal of sequences.[2][6] They demonstrated an intrachromosomal inversion and excision of up to 0.93 megabases of DNA.[3][4] They provided proof of concept for excision of gene regulatory regions or disease-relevant repetitive expansions, including the BCL11A enhancer from sickle cell therapy.[3][4][6] These methods have been tested in human cells with high accuracy.[1][2]