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Phenotypes Associated with This Genotype
Genotype
MGI:3785610
Allelic
Composition
Smn1tm1Msd/Smn1tm1Msd
Grm7Tg(SMN2)89Ahmb/Grm7Tg(SMN2)89Ahmb
Tg(SMN2*delta7)4299Ahmb/Tg(SMN2*delta7)4299Ahmb
Genetic
Background
FVB.Cg-Grm7Tg(SMN2)89Ahmb Smn1tm1Msd Tg(SMN2*delta7)4299Ahmb/J
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Grm7Tg(SMN2)89Ahmb mutation (35 available); any Grm7 mutation (123 available)
Smn1tm1Msd mutation (37 available); any Smn1 mutation (86 available)
Tg(SMN2*delta7)4299Ahmb mutation (13 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• average survival of about 2 weeks

nervous system
• TH staining of the heart to visualize sympathetic innervation indicates that mutants exhibit fewer major neuronal branches and they appear thinner and less distinct
• mice preferentially lack innervation of the caudal band of the levator auris longus
• many endplates are partially occupied or vacant unlike in wild-type mice
• mice exhibit both post- and pre-synaptic pathology at motor neuron endplates

muscle
• muscle fiber diameter is decreased in both slow- and fast-twitch muscles compared to in wild-type mice

cardiovascular system
• hearts appear flaccid and lack defined shape and gross attenuation of walls at P10 and P13
• echocardiography indicates that P6 mice exhibit deficiencies in blood flow out of the right ventricle at the pulmonary valve, with decreased peak velocity and peak gradient, indicating a reduction in pumping efficiency and blood flow from the right ventricle to the lungs
• as mice near end of life, they display a large increase in heart rate variability, ultimately displaying adjacent RR intervals that are highly inconsistent
• mice present bradycardia as early as 2 days of age, before neuromuscular symptoms
• bradyarrhythmia is characterized by progressive heart block and reduced ventricular depolarization efficiency
• at P4, mice have a first-degree heart block characterized by elongated PR interval durations
• at P10, sharp increase in the PR interval and breakdown of cardiac rhythm as mutants exhibit progressive heart block
• elongation of the time of ventricular depolarization through an increase in QRS interval duration beginning at P4

growth/size/body
• begin to lose weight at around P10

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
Werdnig-Hoffmann disease DOID:13137 OMIM:253300
J:164446


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