Phenotypes associated with this allele

• Allele Symbol: Sntb2^tm1Scf
• Allele Name: targeted mutation 1, Stanley C Froehner
• Allele ID: MGI:3574023
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Sntb2^tm1Scf/Sntb2^tm1Scf	involves: 129P2/OlaHsd * C57BL/6	MGI:3574370
cx2	Snta1^tm1Scf/Snta1^tm1Scf Sntb2^tm1Scf/Sntb2^tm1Scf	involves: 129P2/OlaHsd * C57BL/6	MGI:3574371

Genotype
MGI:3574370

hm1

• Allelic Composition: Sntb2^tm1Scf/Sntb2^tm1Scf
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

normal phenotype

no abnormal phenotype detected ( J:96569 )

• homozygous null mice are motile with no signs of muscular dystrophy and are fertile and live up to 2 years under laboratory conditions and have no overt phenotype

Genotype
MGI:3574371

cx2

• Allelic Composition: Snta1^tm1Scf/Snta1^tm1Scf; Sntb2^tm1Scf/Sntb2^tm1Scf
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6

behavior/neurological

decreased locomotor activity ( J:96569 )

• homozygous null mice ran significantly shorter distances on voluntary exercise wheels despite having normal neuromuscular junction transmission

nervous system

abnormal neuromuscular synapse morphology ( J:96569 )

• neuromuscular junctions are structurally more aberrant than those lacking only Snta1, with fewer junctional folds that are abnormally shaped with few openings to the synaptic space

• synaptic levels of acetylcholine receptors (AChR) are reduced to 23% of wildtype

• profound derangement of AChR distribution such as broad fields of AChR organized in dots, short streaks, and fingers, with little hint of a synaptic gutter, and smaller, poorly formed patches of AChR that very greatly in size and most, but not all, of the small AChR accumulations are innervated

• neuromuscular junctions often had small terminals or axon branches (immature contacts) in addition to terminals of normal appearance

abnormal miniature endplate potential ( J:96569 )

• small decrease of the miniature end plate potential (MEPP) amplitude and a decrease of the miniature end plate current (MEPC) amplitude in the diaphragm muscle

• significantly decreased decay time constants for both MEPPs and MEPCs in the diaphragm muscle suggesting either faster channel closure or faster destruction of AChR