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Phenotypes Associated with This Genotype
Genotype
MGI:2680045
Allelic
Composition
Slc12a6tm1Tjj/Slc12a6tm1Tjj
Genetic
Background
involves: 129/Sv * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Slc12a6tm1Tjj mutation (0 available); any Slc12a6 mutation (120 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
hearing/vestibular/ear
• at >1 year, OHCs and IHCs are either both present or both absent in most sections of the organ of Corti
• a few cases where OHCs have degenerated while IHCs are still present are also observed
• the temporal relationship between the degeneration of fibrocytes and hair cells is variable
• at 3 months, 2 of 4 (50%) homozygotes display degeneration of the organ of Corti
• at 5 months or later, 12 of 15 (80%) homozygotes display degeneration of the organ of Corti
• at 5 months or later, homozygotes often show a significant loss of spiral ligament type I fibrocytes
• in contrast, spiral ligament type II fibrocytes are often preserved
• at 5 months or later, homozygotes often show a significant loss of spiral ligament type III fibrocytes
• however, young (<75 days) and old (>110 days) homozygotes show no significant differences in their endocochlear potential or K+ concentration in the scala media relative to age-matched wild-type mice
• old (but not young) homozygotes exhibit a significant decrease in the post-mortem (passive) endocochlear steady-state potential (SSP) relative to wild-type mice
• homozygotes display a slowly progressive hearing loss over the first year of life, as shown by reduced thresholds of auditory brainstem responses to clicks as a function of age

nervous system
• upon exposure to flurothyl, 3-month-old homozygotes show reduced seizure thresholds and increased aberrant electrical activity, including spontaneous high-voltage spike-and-wave-like complexes, on electrocorticograms
• however, no spontaneous seizures are observed
• at P13 (but not at P1), homozygotes exhibit severe degeneration of the cerebellum
• at >1 year, homozygotes display degeneration of the cochlear ganglion, probably secondary to loss of cochlear hair cells
• at P13 (but not at P1), homozygotes display severe degeneration of the sciatic nerve
• at P13 (but not at P1), homozygotes display degeneration of the spinal cord
• analysis of ventral and dorsal roots of the spinal cord indicates that both motor and sensory nerves are affected
• homozygotes exhibit progressive neurodegeneration in the PNS and CNS, esp. in the white matter
• at P13 (but not at P1), homozygotes exhibit severe degeneration of the sciatic nerve, spinal cord, hippocampus, cerebellum, and optic stalk while the corpus callosum remains unaffected
• at >1 year, OHCs and IHCs are either both present or both absent in most sections of the organ of Corti
• a few cases where OHCs have degenerated while IHCs are still present are also observed
• the temporal relationship between the degeneration of fibrocytes and hair cells is variable
• at P13 (but not at P1), homozygotes display severe hippocampal neurodegeneration, esp. in the outer molecular layer of the dentate gyrus along the hippocampal fissure
• vacuolization is more severe at 3 months of age than at P13
• at 3 months, homozygotes exhibit swollen myelinated and unmyelinated axons in their degenerating hippocampi
• degenerating hippocampal unmyelinated axons have synapses that terminate on morphologically intact spines, suggesting that synaptic connections are established prior to degeneration

behavior/neurological
• upon exposure to flurothyl, 3-month-old homozygotes show reduced seizure thresholds and increased aberrant electrical activity, including spontaneous high-voltage spike-and-wave-like complexes, on electrocorticograms
• however, no spontaneous seizures are observed
• when lifted by the tail, 3-week-old homozygotes display abnormal hindlimb grasping instead of the normal extension response
• at >1 year, abnormal forelimb grasping is also observed
• at >1 year, homozygotes sometimes exhibit grossly abnormal positions of their hindlegs while sitting
• at >1 year, homozygotes sometimes lay flat on the ground
• at >1 year, homozygotes are often unable to move their hindlimbs

cardiovascular system
• at 3-5 months, homozygotes exhibit increased arterial hypertension relative to wild-type littermates (118 2 mmHg vs 100 2 mmHg, respectively)
• however, no difference in heart rates are observed

muscle
• at >1 year, homozygotes display an abnormal posture reminiscent of spasticity

vision/eye
• at P13 (but not at P1, homozygotes display degeneration of the optic stalk
• however, no retinal degeneration is observed

cellular
• homozygotes exhibit a severely impaired cell volume regulation, as assessed in proximal renal tubules and hippocampal neurons, and a moderately raised intraneuronal Cl- concentration relative to wild-type mice

skeleton
• at 5 months or later, homozygotes often show a significant loss of spiral ligament type I fibrocytes
• in contrast, spiral ligament type II fibrocytes are often preserved
• at 5 months or later, homozygotes often show a significant loss of spiral ligament type III fibrocytes

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
agenesis of the corpus callosum with peripheral neuropathy DOID:0090003 OMIM:218000
J:86183


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
03/12/2024
MGI 6.23
The Jackson Laboratory