The strain of origin of this Robertsonian translocation was only defined as an albino strain that had not been exposed to any known mutagen in 3 generations of breeding. It was first reported by White and Tjio in 1967 and later sent from Dr. Beverly White to Dr. Eva Eicher at The Jackson Laboratory where it was maintained by sibling inbreeding homozygotes for well over a decade before being backcrossed onto C57BL/6JEi. At generation N8 this strain was intercrossed to homozygosity. Embryos were generated from C57BL/6JEi females bred to homozygous males at generation N8F6. All cryorecovered pups will be heterozygous for this Robertsonian translocation.