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Phenotypes Associated with This Genotype
Genotype
MGI:8187957
Allelic
Composition
\Polr3atm1Iwil/\Polr3atm1Iwil
\Olig2tm1.1(cre)Wdr/\Olig2+
Genetic
Background
involves: 129S1/Sv * 129X1/SvJ * C57BL/6J
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Olig2tm1.1(cre)Wdr mutation (1 available); any Olig2 mutation (45 available)
Polr3atm1Iwil mutation (0 available); any Polr3a mutation (70 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
behavior/neurological
• approximately 60% of females fail to differentiate between familiar and novel objects in the object recognition test
• more than 60% of male and approximately 80% of females fail to differentiation between familiar and novel objects in object placement test
• more than 60% of male and approximately 80% of females fail to differentiation between familiar and novel objects in object placement test
• males exhibit a reduction in the magnitude of the startle reflex at all stimulus intensities
• females exhibit a trend in reduced startle reflex at lower stimuli and significant reduction at 115 dB
• both males and females show a delay to elicit a startle reflex at 115 dB
• in the Hargreaves test of reflex response to thermal sensation, mice show normal increased latency for hind paw withdrawal as a function of stimulus intensity, however the relative response is delayed at lower intensities for males and at all intensities for females, suggesting an impaired sensation and reflex response
• mice show a delay in achieving developmental milestones such as deficits in body-righting mechanisms, strength, coordination, locomotion and the extinguishing of pivoting behavior

growth/size/body
• smaller body size throughout adolescence, with males showing decreased size at 3, 4, and 5 weeks of age and females at 4 and 5 weeks of age
• adults exhibit decreased body weight; body weight difference is maintained in males and is enhanced in females between 3 and 5 weeks of age and differences in body weight are seen at 12 and 16 weeks of age
• mice show reduced weight gain after birth, with body weight difference that is more pronounced in males and increases over time from P5 to P21, in contrast to females that maintain a relatively constant and smaller body weight difference

nervous system
• adolescent and adult mice exhibit reduced numbers of myelinating oligodendrocytes
• adolescent males show a reduction in O4 and MOG double-positive premyelinating- oligodendrocytes while females show only a trend in this reduction
• reduced myelin thickness is seen across a range of axon calibers, indicating a defect in the capacity of mature oligodendrocytes to produce a myelin sheath of normal thickness
• reduction in the size of the white matter tract due to the projection of the ventral horns into the ventrolateral funiculus
• myelin sheath thickness is reduced as indicated by a higher average g-ratio
• reduced myelin thickness is seen across a range of axon calibers
• impaired myelination in adolescent and adult mice with hypomyelination in the corpus callosum splenium, hippocampus, and cerebral cortex, and in the ventral and dorsal horns of the spinal cord and a small reduction in the thymus of adolescent mice but not adults
• however, no differences in myelination in the cerebellum and in Purkinje cell number
• fractional anisotropy is reduced in the anterior commissure, corpus callosum genu and splenium, and the optic tract due to increased radial diffusivity in the absence of effects on axial diffusivity, suggesting a myelin deficiency in these regions
• the optic nerve shows no change in fractional anisotropy but reduced radial diffusivity, axial diffusivity, and mean diffusivity
• mice show an increase in the number of unmyelinated axons with cross-sectional axons greater than the smaller myelinated axons in wild-type mice

cellular
• adolescent and adult mice exhibit reduced numbers of myelinating oligodendrocytes
• adolescent males show a reduction in O4 and MOG double-positive premyelinating- oligodendrocytes while females show only a trend in this reduction
• reduced myelin thickness is seen across a range of axon calibers, indicating a defect in the capacity of mature oligodendrocytes to produce a myelin sheath of normal thickness

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
hypomyelinating leukodystrophy 7 DOID:0060794 OMIM:607694
J:311745


Contributing Projects:
Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO)
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last database update
03/25/2025
MGI 6.24
The Jackson Laboratory