The nervous (nr) mutant mouse displays two gross recessive traits: bot
h an exaggeration of juvenile hyperactivity and a pronounced ataxia be
come apparent during the third and fourth postnatal weeks. Using an in
tersubspecific intercross, we have established a high-resolution map o
f a segment of mouse Chromosome 8 that places the nr locus in a genomi
c segment defined by D8Rck1 on the centromeric end and D8Mit3 on the t
elomeric end. This map position places the nr locus within the BALB/cG
r congenic region of the C3HeB/FeJ-nr strain, confirming the accuracy
of our study. We used this map position to identify and evaluate three
genes-ankyrin 1, cortexin, and farnesyltransferase-as candidates for
the nr gene. These three genes were eliminated from consideration but
allowed us to establish the conservation of synteny between the region
containing the nr locus and a segment of the short arm of human chrom
osome 8 (8p21-p11.2). Finally, the incomplete penetrance of the nr phe
notype led us to perform a screen for modifier loci, and we present ev
idence that such a nervous modifier locus may exist on mouse Chromosom
e 5. (C) 1998 Academic Press.