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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID 		Sim2tm1Fan
targeted mutation 1, Chen-Ming Fan
MGI:2180881
Summary 6 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
cx1
 		Sim1tm1Fan/Sim1+
Sim2tm1Fan/Sim2+ 		involves: 129/Sv * C57BL/6 MGI:3036853
cx2
 		Sim1tm1Fan/Sim1tm1Fan
Sim2tm1Fan/Sim2tm1Fan 		involves: 129S1/Sv * 129X1/SvJ MGI:3613779
cx3
 		Sim1tm1Fan/Sim1tm1Fan
Sim2tm1Fan/Sim2+ 		involves: 129S1/Sv * 129X1/SvJ MGI:3613780
cx4
 		Sim1tm1Fan/Sim1+
Sim2tm1Fan/Sim2tm1Fan 		involves: 129S1/Sv * 129X1/SvJ MGI:3613782
cx5
 		Sim1tm1Jlmd/Sim1tm1Jlmd
Sim2tm1Fan/Sim2tm1Fan 		involves: 129S1/Sv * 129X1/SvJ * C57BL/6 MGI:3613784
cx6
 		Sim1tm1Fan/Sim1tm1Jlmd
Sim2tm1Fan/Sim2tm1Fan 		involves: 129S1/Sv * 129X1/SvJ * C57BL/6 MGI:3613785


Genotype
MGI:3036853
cx1
Allelic
Composition		 Sim1tm1Fan/Sim1+
Sim2tm1Fan/Sim2+
Genetic
Background		 involves: 129/Sv * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Fan mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
growth/size/body
increased susceptibility to weight gain ( J:76787 )
• after 7 months the average weight was identical to that of mice heterozygous only for Sim1tm1Fan

nervous system
abnormal diencephalon morphology ( J:76787 )
• paraventricular nucleus and supraoptic nuclei are hypocellular
• the phenotype is identical to that of mice heterozygous only for Sim1tm1Fan

Mouse Models of Human Disease
 DO ID OMIM ID(s) Ref(s)
obesity DOID:9970 OMIM:601665
 J:76787




Genotype
MGI:3613779
cx2
Allelic
Composition		 Sim1tm1Fan/Sim1tm1Fan
Sim2tm1Fan/Sim2tm1Fan
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Fan mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
nervous system
abnormal nervous system tract morphology ( J:104419 )
• at E18.5, the principal mammillary axonal tract appears thin and the mammilothalmic tract is undetectable
• most mammillary body axons are directed towards the midline with some becoming splayed and others forming a bundle that crosses the midline ventrally




Genotype
MGI:3613780
cx3
Allelic
Composition		 Sim1tm1Fan/Sim1tm1Fan
Sim2tm1Fan/Sim2+
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Fan mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
nervous system
abnormal nervous system tract morphology ( J:104419 )
• at E18.5, the principal mammillary axonal tract appears less prominent similar to mice homozygous for Sim1tm1Fan alone




Genotype
MGI:3613782
cx4
Allelic
Composition		 Sim1tm1Fan/Sim1+
Sim2tm1Fan/Sim2tm1Fan
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Fan mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
nervous system
abnormal nervous system tract morphology ( J:104419 )
• at E18.5, the principal mammillary axonal tract appears less prominent similar to mice homozygous for Sim1tm1Fan alone




Genotype
MGI:3613784
cx5
Allelic
Composition		 Sim1tm1Jlmd/Sim1tm1Jlmd
Sim2tm1Fan/Sim2tm1Fan
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Jlmd mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
nervous system
abnormal nervous system tract morphology ( J:104419 )
• at E18.5, the principal mammillary axonal tract and mammilothalmic tract are absent
• on the mammillary body in the location of the principal mammillary axonal tract a group of ectopic axons is seen and at the most posterior level of the mammillary body these axons cross the midline ventrocaudally to the third ventricle




Genotype
MGI:3613785
cx6
Allelic
Composition		 Sim1tm1Fan/Sim1tm1Jlmd
Sim2tm1Fan/Sim2tm1Fan
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Sim1tm1Fan mutation (0 available); any Sim1 mutation (54 available)
Sim1tm1Jlmd mutation (0 available); any Sim1 mutation (54 available)
Sim2tm1Fan mutation (0 available); any Sim2 mutation (23 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
nervous system
abnormal axon morphology ( J:104419 )
• at E11.5 mammillary body axon bundles are not detectable




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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Send questions and comments to User Support. 		last database update
09/30/2025
MGI 6.24 		The Jackson Laboratory