About   Help   FAQ
Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID 		Mef2b+
wild type
MGI:2433230
Summary 4 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
cn1
 		Ighg1tm1(cre)Cgn/0
Mef2btm1.1Rdf/Mef2b+ 		involves: 129P2/OlaHsd * C57BL/6 MGI:6401143
cn2
 		Ighg1tm1(cre)Cgn/0
Mef2btm2Rdf/Mef2b+ 		involves: 129P2/OlaHsd * C57BL/6 MGI:6401148
cn3
 		Mef2btm2Rdf/Mef2b+
Tg(BCL2/IGH)M23Tjd/0
Tg(Cr2-cre)3Cgn/0 		involves: C3H/He * C57BL/6 MGI:6401158
cn4
 		Mef2btm2Rdf/Mef2b+
Tg(Cr2-cre)3Cgn/0 		involves: C57BL/6 MGI:6401150


Genotype
MGI:6401143
cn1
Allelic
Composition		 Ighg1tm1(cre)Cgn/0
Mef2btm1.1Rdf/Mef2b+
Genetic
Background		 involves: 129P2/OlaHsd * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Ighg1tm1(cre)Cgn mutation (4 available); any Ighg1 mutation (30 available)
Mef2btm1.1Rdf mutation (0 available); any Mef2b mutation (20 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
hematopoietic system
decreased germinal center B cell number ( J:265465 )
• modest reduction in number 10 days after immunization with sheep red blood cells (SRBCs)
• reduced dark zone (DZ)/light zone (LZ) ratio owing to reduced number of cells in DZ

immune system
decreased germinal center B cell number ( J:265465 )
• modest reduction in number 10 days after immunization with sheep red blood cells (SRBCs)
• reduced dark zone (DZ)/light zone (LZ) ratio owing to reduced number of cells in DZ




Genotype
MGI:6401148
cn2
Allelic
Composition		 Ighg1tm1(cre)Cgn/0
Mef2btm2Rdf/Mef2b+
Genetic
Background		 involves: 129P2/OlaHsd * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Ighg1tm1(cre)Cgn mutation (4 available); any Ighg1 mutation (30 available)
Mef2btm2Rdf mutation (0 available); any Mef2b mutation (20 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
hematopoietic system
abnormal mature B cell morphology ( J:265465 )
• increased GC B cell number 10 days after immunization with sheep red blood cells (SRBCs)
• larger GC B cells 10 days after immunization with sheep red blood cells (SRBCs)
• normal non-GC B cell numbers 10 days after immunization with sheep red blood cells (SRBCs)
increased germinal center B cell number ( J:265465 )
• 10 days after immunization with sheep red blood cells (SRBCs)
• reduced dark zone (DZ)/light zone (LZ) ratio owing to reduced number of cells in DZ and increased number in LZ

immune system
abnormal mature B cell morphology ( J:265465 )
• increased GC B cell number 10 days after immunization with sheep red blood cells (SRBCs)
• larger GC B cells 10 days after immunization with sheep red blood cells (SRBCs)
• normal non-GC B cell numbers 10 days after immunization with sheep red blood cells (SRBCs)
increased germinal center B cell number ( J:265465 )
• 10 days after immunization with sheep red blood cells (SRBCs)
• reduced dark zone (DZ)/light zone (LZ) ratio owing to reduced number of cells in DZ and increased number in LZ




Genotype
MGI:6401158
cn3
Allelic
Composition		 Mef2btm2Rdf/Mef2b+
Tg(BCL2/IGH)M23Tjd/0
Tg(Cr2-cre)3Cgn/0
Genetic
Background		 involves: C3H/He * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Mef2btm2Rdf mutation (0 available); any Mef2b mutation (20 available)
Tg(BCL2/IGH)M23Tjd mutation (0 available)
Tg(Cr2-cre)3Cgn mutation (2 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
neoplasm
increased lymphoma incidence ( J:265465 )
• plasmablastic lymphoma (PBL) in 20% of mice at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)
increased follicular lymphoma incidence ( J:265465 )
• in 40% of mice at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)




Genotype
MGI:6401150
cn4
Allelic
Composition		 Mef2btm2Rdf/Mef2b+
Tg(Cr2-cre)3Cgn/0
Genetic
Background		 involves: C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Mef2btm2Rdf mutation (0 available); any Mef2b mutation (20 available)
Tg(Cr2-cre)3Cgn mutation (2 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
hematopoietic system
enlarged spleen ( J:265465 )
• observed occasionally at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)
abnormal mature B cell morphology ( J:265465 )
• increased GC B cell number 10 days after immunization with sheep red blood cells (SRBCs)
• normal non-GC B cell numbers 10 days after immunization with sheep red blood cells (SRBCs)
increased germinal center B cell number ( J:265465 )
• 10 days after immunization with sheep red blood cells (SRBCs)

immune system
enlarged spleen ( J:265465 )
• observed occasionally at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)
abnormal mature B cell morphology ( J:265465 )
• increased GC B cell number 10 days after immunization with sheep red blood cells (SRBCs)
• normal non-GC B cell numbers 10 days after immunization with sheep red blood cells (SRBCs)
increased germinal center B cell number ( J:265465 )
• 10 days after immunization with sheep red blood cells (SRBCs)
enlarged mesenteric lymph nodes ( J:265465 )
• at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)
enlarged lymph nodes ( J:265465 )
• in 28% of mice at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)

neoplasm
increased B cell derived lymphoma incidence ( J:265465 )
• at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)

growth/size/body
enlarged spleen ( J:265465 )
• observed occasionally at age 17-18 months after chronic immunization with sheep red blood cells (SRBCs)




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)
Citing These Resources
Funding Information
Warranty Disclaimer, Privacy Notice, Licensing, & Copyright
Send questions and comments to User Support. 		last database update
01/06/2026
MGI 6.24 		The Jackson Laboratory