The KitlSl-22J mutation arose spontaneously at The Jackson Laboratory in 2004 on the C57BL/6J-Ins2Akita/J background. Although no allele test could be performed, mapping and phenotype support the idea that this is an allele of Kitl. This strain has been maintained by sibling breeding heterozygotes with wildtype and vice versa. In 2007 this strain reached generation +F9. Throughout this time, no indication of the Akita mutation has been seen.