A new neurological rat mutant "mutilated foot".

Abstract A new autosomal recessive mutant rat (mutilated foot) with a neurological disorder is described. Affected animals become ataxic and the feet, generally of the hind limbs, are mutilated. Quantitative studies show a severe reduction in numbers of sensory ganglion cells and fibres, including unmyelinated fibres. The numbers of ventral root fibres, particularly those of small diameter, are also reduced. Markedly decreased numbers of spindles are found in the limb muscles. These quantitative abnormalities are present in animals of all ages and appear to be congenital. No nerve fibre degeneration is found in the spinal cord of young animals, but progressive degeneration of ascending tracts is seen with increasing age. Mossy fibre degeneration in the cerebellum confirms that the spinocerebellar tract is affected. The neurological disease in this mutant shows many similarities to that found in human hereditary sensory neuropathy.