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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID 		Jak2tm1Jni
targeted mutation 1, James N Ihle
MGI:2178844
Summary 3 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
hm1
 		Jak2tm1Jni/Jak2tm1Jni involves: 129P2/OlaHsd MGI:3583267
ht2
 		Jak2tm1Jni/Jak2+ involves: 129P2/OlaHsd MGI:5562427
ht3
 		Jak2m1Dlbr/Jak2tm1Jni involves: 129P2/OlaHsd * 129S1/SvImJ * C57BL/6J MGI:5562428


Genotype
MGI:3583267
hm1
Allelic
Composition		 Jak2tm1Jni/Jak2tm1Jni
Genetic
Background		 involves: 129P2/OlaHsd
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Jak2tm1Jni mutation (0 available); any Jak2 mutation (60 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
mortality/aging
lethality throughout fetal growth and development, complete penetrance ( J:207740 )
• although present at E12.5, no viable mice are present at E14.5
prenatal lethality, complete penetrance ( J:47299 )
• embryonic death at some time after E10-E12

hematopoietic system
abnormal megakaryocyte differentiation ( J:47299 )
• failure of precursor cells to respond to thrombopoietin
abnormal erythropoiesis ( J:47299 )
• failure of precursors to respond to erythropoietin
extramedullary hematopoiesis ( J:47299 )
• failure of hematopoiesis in the fetal liver
anemia ( J:207740 )
• at E12.5

cellular
abnormal megakaryocyte differentiation ( J:47299 )
• failure of precursor cells to respond to thrombopoietin




Genotype
MGI:5562427
ht2
Allelic
Composition		 Jak2tm1Jni/Jak2+
Genetic
Background		 involves: 129P2/OlaHsd
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Jak2tm1Jni mutation (0 available); any Jak2 mutation (60 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
hematopoietic system
hematopoietic system phenotype ( J:207740 )
N
• bone marrow exhibits normal CFU-megakaryocyte assays
• mice exhibit normal response to 5-fluorouracil and phenylhydrazine challenge
decreased erythrocyte cell number ( J:207740 )
• in male, but not female, mice




Genotype
MGI:5562428
ht3
Allelic
Composition		 Jak2m1Dlbr/Jak2tm1Jni
Genetic
Background		 involves: 129P2/OlaHsd * 129S1/SvImJ * C57BL/6J
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Jak2m1Dlbr mutation (0 available); any Jak2 mutation (60 available)
Jak2tm1Jni mutation (0 available); any Jak2 mutation (60 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
mortality/aging

hematopoietic system
anemia ( J:207740 )
• at E12.5 and E14.5




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