Mouse Genome Informatics
involves: FVB/N
phenotype observed in females
phenotype observed in males
N normal phenotype
• limb clasping is observed when mutants are suspended by the tail
• mutants start to show impaired behavior on an accelerating rotarod starting at 6 months of age and progressive worsening over time
• mutants exhibit a more pronounced decline on the rotarod than Tg(Thy1-HSPB1*S135F)#Lvdb mutants
• progressive decline in grip strength of all paws
• mutants show a more severe decline in grip strength than Tg(Thy1-HSPB1*S135F)#Lvdb mutants
• mutants show hesitations in placing their paws and have increased hindpaw angles and decreased hindpaw print areas
• mutants exhibit a disturbed gait from 6 months of age, needing on average twice the number of step cycles to cross the walkway than controls, resulting in a 50% reduction of stride length

• mutants exhibit atrophic muscle fibers in the gastrocnemius muscle accompanied by pyknotic nuclear clumps
• gastrocnemius muscle has less acetylcholine receptor clusters per terminal axon

nervous system
• decrease in acetylated alpha-tubulin abundance in peripheral nerves of symptomatic mutants
• motor axonal loss
• sensorimotor axonal loss
• mutants exhibit an increase of denervated neuromuscular junctions
• decrease in the number of axons in distal parts of the sciatic nerve but not in the proximal parts
• mutants exhibit a decrease in peak-to-peak amplitude of compound muscle action potentials (CMAPs) at 6 months of age
• from 6 months of age, mutants show a decrease in baseline-to-peak amplitude of sensory nerve action potentials (SNAPs), however SNAP latencies are unaltered, indicating that sensory loss is due to an axonal neuropathy

Mouse Models of Human Disease
Neuronopathy, Distal Hereditary Motor, Type IIB; HMN2B 608634 J:174508