%A Dr. Robert P. Bauchwitz
%J Genes, Brain and Behavior
%T A phenotypic and molecular characterization of the fmr1-tm1Cgr Fragile X mouse
%X Fragile X Syndrome is the most common form of
inherited mental retardation. It is also known for having
a substantial behavioral morbidity, including autistic features. In humans, Fragile X Syndrome is almost always
caused by inactivation of the X-linked FMR1 gene. A
single knockout mouse model, fmr1-tm1Cgr, exists. In
this report we further characterize the cognitive and
behavioral phenotype of the fmr1-tm1Cgr Fragile X
mouse through the use of F1 hybrid mice derived from
two inbred strains (FVB/NJ and C57BL/6J). Use of F1
hybrids allows focus on the effects of the fmr1-tm1Cgr
allele with reduced influence from recessive alleles
present in the parental inbred strains. We find that the
cognitive phenotype of fmr1-tm1Cgr mice, including
measures of working memory and learning set formation
that are known to be seriously impacted in humans with
Fragile X Syndrome, are essentially normal. Further testing of inbred strains supports this conclusion. Thus, any
fmr1-tm1Cgr cognitive deficit is surprisingly mild or
absent. There is, however, clear support presented for a
robust audiogenic seizure phenotype in all strains tested,
as well as increased entries into the center of an open
field. Finally, a molecular examination of the fmr1-tm1Cgr
mouse shows that, contrary to common belief, it is not a
molecular null. Implications of this finding for interpretation of the phenotype are discussed.

%K audiogenic seizure, Barnes maze, Fmr1 RNA,
Fragile X, hybrid mouse strain, Morris water maze,
olfactory sequence learning, open field, radial maze,
working memory
%P 337-359
%V 3
%D 2004
%I Blackwell Munksgaard 
%L cogprints6539

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