Phenotypes Associated with This Genotype

Genotype
MGI:6715340

• Allelic Composition: Fmr1^tm1.1Ics/Fmr1^tm1.1Ics
• Genetic Background: C57BL/6-Fmr1^tm1.1Ics

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

behavior/neurological

abnormal response to novel object ( J:304982 )

• in the novel object recognition test, mice spend less time than wild-type mice exploring the novel object and more time sniffing the old object, showing a lower discrimination index

abnormal response to social novelty ( J:304982 )

♂ • the time spent sniffing the novel social stimulus and the ability to discriminate between the novel mouse and the empty cage are reduced in males, but not females

decreased vocalization ( J:304982 )

• pups removed from the nest show an approximate 50% decrease in the number of ultrasonic vocalizations

nervous system

increased dendritic spine density ( J:304982 )

• cultured hippocampal neurons show an increase in spine density

• hippocampal neurons in the CA1 region show an increase in spine density both in basal and apical dendrites

• however, length of dendritic spines is normal

abnormal postsynaptic density morphology ( J:304982 )

• the postsynaptic density thickness in hippocampal neurons is reduced

• however, no difference in the length of the postsynaptic densities

abnormal excitatory synapse morphology ( J:304982 )

• increase in the density of excitatory synapses in the hippocampus

abnormal synaptic vesicle number ( J:304982 )

• increase in the density of synaptic vesicles in hippocampal presynaptic termini

impaired synaptic plasticity ( J:304982 )

• hippocampal plasticity is severely impaired

reduced long-term potentiation ( J:304982 )

♂ • induction of long-term potentiation by high-frequency stimulation in the hippocampus is reduced in males; impaired LTP is most likely due to postsynaptic impairments rather than presynaptic alterations as no difference in mean fiber volley slope is seen

increased miniature excitatory postsynaptic current amplitude ( J:304982 )

• CA1 hippocampal neurons exhibit enhanced amplitude of AMPAR-mediated miniature excitatory postsynaptic currents

• however, no differences in the frequency of mEPSCs or the kinetics of these events are seen

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
fragile X syndrome		DOID:14261	OMIM:300624	J:304982