The spontaneous dominant mutation extra toes and odd legs (Xtol) causes heterozygotes to have malformed toes on all four feet and pronounced deformity of the rear legs. The toe deformities include polydactyly, syndactyly, and shortening. The rear legs may be twisted, misplaced on the body or otherwise misshapen, affecting the gait in some heterozygotes. This phenotype varies in expressivity with some heterozygotes having more severely twisted legs and malformed toes than others. Both female and male heterozygotes have bred and generally live a normal lifespan. Breeding heterozygous females or males with C57BL/6J mates produced 36 affected offspring out of 96 progeny (38.1%), less than predicted by Mendelian inheritance and indicative of some prenatal lethality.
The extra toes-like mutation (Xtol) arose spontaneously in the C57BL/6J inbred strain at The Jackson Laboratory and was maintained coisogenic. Sperm was cryopreserved from heterozygous males.
When using the extra toes and odd legs mouse strain in a publication, please cite the originating article(s) and include JAX stock #018924 in your Materials and Methods section.