In this study, we used a variety of molecular cytological and genetic technologies to map the transgene insertion-chromosome deletion breakpoints of a mouse model of PWS and AS to ~38 kb regions between the Luzp2 and Siglec-H genes at the centromeric end and within Chrna7 intron 4 at the telomeric end, respectively. This evidence concerns the gene LUZP2 and Prader-Willi syndrome.