a single chain meganuclease comprises an n terminal domain and a c terminal domain joined by a linker peptide each of the two domains recognizes half of the recognition sequence and the site of dna cleavage is at the middle of the recognition sequence near the interface of the two subunits dna strand breaks are offset by four basepairs such that dna cleavage by a meganuclease generates a pair of four basepair 3 u2032 single strand overhangs in a preferred embodiment single chain meganucleases are selected which cut recognition sequences with complementary overhangs as in examples 1 and 2 example recognition sequences for dmd exons 44 45 and 51 are listed in tables 2 7 to excise exon 44 for example a first meganuclease can be selected which cuts a recognition sequence from table 2 which lists recognition sequences upstream of exon 44 a second meganuclease can then be selected which cuts a recognition sequences from table 3 which lists recognition sequences downstream of exon 44 co expression of the two meganucleases in the same cell will thus excise exon 44 preferably meganucleases are selected which cut dna to leave complementary single strand overhangs for example seq id no 19 if cut by a meganuclease leaves the overhang sequence 5 u2032 gtac 3 u2032 likewise seq id no 42 if cut by a meganuclease leaves the overhang sequence 5 u2032 gtac 3 u2032 thus co expressing a first meganuclease which cleaves seq id no 19 with a second meganuclease which cleaves seq id no 42 will excise dmd exon 44 from the.