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Phenotypes Associated with This Genotype
Not Specified
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Glrbspa mutation (2 available); any Glrb mutation (25 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
• percentage of mortality is high before or around weaning, although some can live almost a normal life span

• suffer from periods of spasticity which vary in length from one to several minutes; they walk in short steps, on tip-toe and arch their backs (J:5196)
• spasticity is induced by sudden handling (J:5196)
• sudden disturbance or handling causes spasms in which the back is stiff and arched, the legs are stiff and stretched, and the toes are extended (J:13079)
• when held by their tails, backs become stiff and bodies and legs quiver with a high frequency of vibration (J:13079)
• mutants are recognizeable by 14 days of age (J:13079)

• during a spasm, have great difficulty in turning over after being laid on the table with the belly facing upward
• exhibit increased startle responses to acoustic stimuli of different intensities
• when lifted up by the tail, backs stiffen and the entire body and legs quiver violently, indicating tremor
• lack facility in swimming
• in severe cases of spasms, mutants are arch-backed and slide on the table
• walk on tip-toe during a stimulus-induced spasm
• walk in short steps during a stimulus-induced spasm
• females produce young but are poor mothers, possibly because of physical difficulties

reproductive system
• frequency of litters from abnormal males is much lower

• vertebral column abnormalities, with the lumbar region most severely affected, that include intervertebral enchondrosis, hyperplasia of fibrocartilage, and intervertebral arthrosis, probably resulting from disc herniations and ossification
• as early as 24 days of age, exhibit formation of leptomeningeal cysts in the vertebral column, usually located medial to spinal nerve roots
• cysts are lined with a single or multiple layer of cuboidal epithelium and filled with a mucoid fluid and cellular debris and are located between the dura and the spinal cord
• the dorsal longitudinal ligament is thinner dorsally than medially
• in older mutants, the mucoid material ossifies and adheres to the spinal meninges
• acute or subacute disc herniations; rupture of the annulus fibrosus leading to extrusion of the nucleus pulposus
• herniations of the nucleus pulposus are always dorsal or dorsolateral rather than medially
• skeleton becomes brittle with increasing age

nervous system
• occasionally Purkinje cells are lost
• as cysts become distended with fluid, the dura is displaced laterally against the wall of the vertebral canal
• necrobiotic changes involve the neurons of the spinal ganglia with certain of these calcifying and many have eccentric nuclei
• compression of the spinal roots by leptomeningeal cysts, leading to impingment of spinal root axons
• nerve fiber myelin and axonal changes occur in spinal roots, spinal nerves, cauda equina, and sciatic nerves
• disc protrusions indent the ventral aspects of the spinal cord; indentations are often deep enough to alter the normal shape and symmetry of the spinal cord both in the white and grey matter
• white matter atrophies at the sites of compression
• ventral horn neurons become flattened or stretched due to the compression of the spinal cord and undergo degenerative changes, such as shrinkage, vacuolation, and necrobiosis

cardiovascular system
• disk herniations cause hemorrhage

endocrine/exocrine glands
• adrenal corticism is more evident in older mutants, beginning at about 2 months of age
• enlarged due to cortical hypertrophy and hyperplasia


• disc herniations cause edema

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
hyperekplexia 2 DOID:0060697 OMIM:614619

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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MGI 6.19
The Jackson Laboratory