Mice homozygous for the myotonia spontaneous mutations exhibit classical myotonia similar to that described in human myotonic diseases. Homozygous mutant mice are recognizable at 2 weeks of age or earlier by prolonged, stiff extension postures of the limbs when the cage is shaken or the mouse is dropped from about 10 cm. This behavior persists throughout life. When undisturbed, affected animals walk almost normally, although somewhat stiffly. They grow more slowly and weigh about 40% less than controls in adulthood. Electromyographic studies revealed changes characteristic of myotonia. These discharges do not originate in peripheral nerves, and there is no evidence of muscle fiber necrosis.
Myotonia 2J arose spontaneously at The Jackson Laboratory in 1987 in CByJ.Cg-Foxn1nu/J (Stock No. 000711) when that strain was at generation N5F1. This mutant subline was maintained by mating progeny tested siblings and in 2001 it was again backcrossed to BALB/cBy and tested sibling matings were continued. Embryos were generated for cryopreservation from BALB/cByJ females and heterozygous males.
|Allele Name||myotonia 2 Jackson|
|Gene Symbol and Name||Clcn1, chloride channel, voltage-sensitive 1|
|Strain of Origin||BALB/cByOu-Foxn1nu|
|General Note||Allelism testing showed this mutation to be allelic to Clcn1adr-mto (J:14251).|
When using the myotonia 2 Jackson mouse strain in a publication, please cite the originating article(s) and include JAX stock #001265 in your Materials and Methods section.