The genomic sequence containing Myh1 and Myh4 (chr11:67090295-67152081 GRCm39) was inverted using sgRNAs (targeting ATGAGTGTGTGGCTAGGCAACGG, GTGGCTAGGCAACGGTTTGGGGG, ATGATTTGACAGTGAGTCAGAGG, GGGTTCTCATGCTAACACAGAGG, AAGTGAAGTGGATAACCACAGGG and CAGAATGGCAGACGGCCCTGTGG) with CRISPR/Cas9 technology. (J:322002)