Myotonic dystrophy type 1 (DM1) is a genetic disorder which compromises multiple organs and for which investigators lack a suitable mouse model for mechanistic end potential drug screening studies.Yin and colleagues using the latest genetic editing method,the CRISPR-Cas9 technique,started from newly established androgenic haploid embryonic stem cells to make a triple heterozygous mutant DM1 mouse model,as well as a quadruple heterozygous mutant DM1 mouse model,which faithfully recapitulates the pathological phenotypes of human DM1.