An I-CreI variant which has at least two substitutions, one in each of the two functional subdomains of the LAGLIDADG (SEQ ID NO: 229) core domain situated from positions 26 to 40 and 44 to 77 of I-CreI, said variant being able to cleave a DNA target sequence from a xeroderma pigmentosum gene. Use of said variant and derived products for the prevention and the treatment of Xeroderma pigmentosum.