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Phenotypes Associated with This Genotype
Genotype
MGI:5702409
Allelic
Composition
Sacstm2Bebr/Sacstm2Bebr
Genetic
Background
involves: C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sacstm2Bebr mutation (1 available); any Sacs mutation (86 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
nervous system
• axons of Purkinje cells have numerous swellings called torpedoes, characteristic of axon degeneration; swellings are seen as early as 30 days of age and the number of axonal swellings increase with time
• swellings are more prominent in axons arising from the anterior versus posterior cerebellar lobules
• progressive Purkinje cell loss by 90 days of age, restricted to the anterior medial part of the cerebellum
• Purkinje cell loss extends to the cerebellar hemispheres, the simple lobule and the medial part of the ansiform crus 1 lobule without affecting the parafloccular lobes
• motor neurons of dissociated spinal cord cultures show a delay in maturation of about 2 weeks
• spinal cord motor neurons show neurofilament accumulation
• mitochondrial motility is reduced in axons of motor neurons, with only 8% of mitochondria undergoing unidirectional movement compared with 32% in axons of control cultures; percentage of motile mitochondria in axons decreases even further with increased passage of cells
• mitochondrial length is similar in motor neuron cultures at division 21 but is drastically increased at division 35
• spinal motor neurons show a decrease in the number of large (7-10 um diameter) myelinated axons and an increase in the relative number of axons of diameter of 3-4 um
• numbers of spinal motor neurons at L5 level are reduced 25% at 2 years of age
• slight increase in neurofilaments in proximal dendrites at P14
• corticospinal axons show signs of degeneration at 2 years of age
• however, the number of corticospinal axons does not change

behavior/neurological
• 365 day old mice exhibit hindlimb clasping when held by the tail
• seen by 15 months of age
• mutants take more time to cross the balance beam and display a greater number of foot slips as early as 40 days of age
• mutants take more time to cross the balance beam and display a greater number of foot slips as early as 40 days of age
• mice show impaired performance on the rotorod test, with the most significant differences at 90 days of age
• females show a progressive decrease in muscle strength in the inverted grid test starting at 120 days of age
• mice show abnormal gait characterized by the lateral spreading of their rear paws between 7 and 10 months of age with gait abnormalities becoming more pronounced by 15 months

muscle
• gastrocnemius muscle shows some angular atrophic muscle fibers and hypertrophic fibers
• gastrocnemius muscle shows some angular atrophic muscle fibers and hypertrophic fibers
• calf muscle exhibits loss in weight of gastrocnemius muscle and to a smaller degree, the soleus at 2 years of age
• calf muscle exhibits loss in weight of gastrocnemius muscle and to a smaller degree, the soleus at 2 years of age

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
Charlevoix-Saguenay spastic ataxia DOID:0050946 OMIM:270550
J:217753


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
02/23/2021
MGI 6.16
The Jackson Laboratory