Stock No. 007249 was assigned to the mixed B6;129 genetic background line of Smn1 COIN conditional inversion (Smn1tm3(SMN2/Smn1)Mrph) mice. While mutant mice on the mixed B6;129 genetic background are no longer available, mice harboring the same Smn1tm3(SMN2/Smn1)Mrph allele are available on an FVB congenic background (Stock No. 007964) and a C57BL/6 congenic background (Stock No. 007966).