Leg dragger homozygotes are slightly smaller than their unaffected littermates and lose most of the use of their rear legs such that they drag their rear legs and pull themselves along with their front legs to move. This phenotype can be detected as early as 2 weeks of age and is evident by 3 weeks of age. A few homozygotes nearing wean age are found to roll over and over in a struggle to right themselves. When raised by their tails they do not splay their legs outward but rather cross the front pair and the rear pair. Auditory brainstem response analysis of one homozygous animal at 18 days of age showed severe hearing loss and no others were tested. Heterozygotes appear normal and fertile but produce slightly fewer homozygotes than the 25% expected when intercrossed.

 The leg dragger mutation provides a viable mutation in kinesin family member 1A that causes pre-wean hindleg paralysis, whereas a targeted null mutation causes perinatal lethality. This strain provides a model for autosomal recessive spastic paraplegia 30.

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