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The mutants can be detected at or shortly after weaning age (average age of onset 5 weeks +/-1.9; n=9). They are small, show body tremor, splayed hind limbs, and might advance with both hind limbs simultaneously, in a 'frog-like' manner. Intermittently, body spasms can be observed, which may be limited to one or the other hind- or fore limb, or to the head, neck, shoulder and front limb area, or include the whole body, so the animal needs to lie on its side. Either episode may last for several seconds. Because of the observed body spasms and splayed hind limbs, allele tests were performed with Cacna2d2 (calcium channel, voltage-dependent, alpha 2/delta subunit 2) or Cacnb4 (calcium channel, voltage-dependent, beta 4 subunit) mutants. The results showed NMF299 to be an allele of Cacna2d2, i.e. 2 heterozygous matings (w/ducky-2J) resulted in 2 affected mice in a total of 12 progeny. NMF299 are now backcrossed to the BALB/cByJ background. With special care and feeding mutants can live to over 2 months of age, without it, they may die as early as 4 weeks of age. Males are fertile, females may require ovarian transplants. Standard pathology work-up on one mutant (57 days of age) showed no abnormalities, except body and organs to be small and immature.
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