This strain is homozygous for the retinal degeneration allele Pde6brd1.
Mice homozygous for the myotonia spontaneous mutations exhibit classical myotonia similar to that described in human myotonic diseases. Homozygotes 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.
The myotonia mutation arose spontaneously on the SWR/J inbred background at The Jackson Laboratory in 1972, when that inbred was at generation F105, and was maintained coisogenic on this background by sibling breeding. In 1995 heterozygous males at generation +F47 were bred with either +/? or SWR/J inbred females to generate embryos for cryopreservation.
|Gene Symbol and Name||Clcn1, chloride channel, voltage-sensitive 1|
|Strain of Origin||SWR/J|
|Molecular Note||A nonsense mutation at codon 47 (C to T substitution) changes an arginine residue into a stop codon ahead of the first transmembrane region of Clcn1. Northern analyses of adult skeletal muscle using a 5' and a 3' rat cDNA Clcn1 probe detected wild-type size transcript in homozygous mutant mice (J:752).|
Until at least 7 weeks of age, homozygotes require a wildtype companion for warmth in shipping.
When using the myotonia mouse strain in a publication, please cite the originating article(s) and include JAX stock #000939 in your Materials and Methods section.