1. A method for modifying a chromosomal sequence in a eukaryotic cell, the method comprising:
a) introducing into the eukaryotic cell two RNA-guided nickase systems or nucleic acid encoding said systems, and, optionally, a donor polynucleotide,
wherein each RNA-guided nickase system comprises
(i) a RNA-guided endonuclease that is modified to cleave one strand of a double-stranded sequence; and
(ii) a guide RNA comprising a first region having complementarity to a target site in the chromosomal sequence and a second region that interacts with the RNA-guided endonuclease,
wherein each target site is immediately followed by a protospacer adjacent motif (PAM), and the target sites of the two RNA-guided endonucleases are on opposite strands of the chromosomal sequence; and
b) culturing the eukaryotic cell such that the two RNA-guided endonucleases cleave opposite strands of the chromosomal sequence in close enough proximity to introduce a double-stranded break in the chromosomal sequence, and repair of the double-stranded break by a DNA repair process leads to modification of the chromosomal sequence,
wherein the method does not comprise a process for modifying the germ line genetic identity of a human being and,
wherein the method does not comprise a method for treatment of the human or animal body by surgery or therapy.
・HRの修復を使った核酸の導入×ニッカーゼ型
・ニッカーゼは、Cas9に限定されず、RNAガイドエンドヌクレアーゼ(他のCasを含む)