Early detection of mouse wobbler mutation: a model of pathological motoneurone death

The mouse recessive mutation wobbler, carried by the C57BL/6J strain, is a naturally occurring model of motoneurone death. The gene is unknown and in the absence of predictive markers, mutants have to be diagnosed by phenotypic criteria at 4 weeks after birth. We localized the wobbler gene to chromosome 11 at 0.98 +/- 1.1 cM from the glutamine synthetase (Glns) gene. A polymorphic allele of the Glns gene was then introduced into the congenic wobbler strain by intraspecific crossing. One-quarter of the offspring expressed the same phenotypic mutation as true wobbler and were detectable by PCR, as they are homozygous for the wobbler-linked Glns allele. The new mutants exhibit motoneurone degeneration despite the new genetic background.