MBP knockout mice called shiverer mice were subsequently developed and characterized in the early 1980s. The shiverer mouse represents one animal model of dysmyelination. Axons in "shiverer" mice fail to attain a normal diameter and exhibit altered cytoskeleton structure. The "shiverer" mutation is an autosomal recessive loss-of-function mutation. Approximately twelve days after birth, "shiverer" mice begin to exhibit tremors which progressively worsen.