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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID 		Pax1+
wild type
MGI:1857559
Summary 5 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
ht1
 		Pax1un-i/Pax1+ either: (involves: 129S1/Sv * 129X1/SvJ) or (involves: 129S1/Sv * 129X1/SvJ * C57BL/6J) MGI:3603924
ht2
 		Pax1tm1Neu/Pax1+ involves: 129S1/Sv * 129X1/SvJ * C57BL/6 MGI:3845244
ht3
 		Pax1Un-s/Pax1+ involves: CC57BR/MvY MGI:5635923
cx4
 		Pax1un/Pax1+
Tcf3tm1Cmu/Tcf3tm1Cmu 		involves: 129P2/OlaHsd * C3H * C57BL/6 MGI:3776838
cx5
 		kkt/kkt+
Pax1un/Pax1+ 		involves: C57BL/6 * CBA MGI:4437579


Genotype
MGI:3603924
ht1
Allelic
Composition		 Pax1un-i/Pax1+
Genetic
Background		 either: (involves: 129S1/Sv * 129X1/SvJ) or (involves: 129S1/Sv * 129X1/SvJ * C57BL/6J)
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Pax1un-i mutation (0 available); any Pax1 mutation (26 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
immune system
decreased thymocyte number ( J:100951 )
• at E17.5, E19.5 and 6 weeks of age, thymocyte numbers are significantly reduced compared to wild-type mice but increased compared to homozygous mutants
decreased CD4-positive, alpha-beta T cell number ( J:100951 )
• the number of CD4+ cells is decreased at 6 weeks of age compared to wild-type mice but increased compared to homozygous mutants
decreased CD8-positive, alpha-beta T cell number ( J:100951 )
• the number of CD8+ cells is decreased at 6 weeks of age compared to wild-type mice but increased compared to homozygous mutants

hematopoietic system
decreased thymocyte number ( J:100951 )
• at E17.5, E19.5 and 6 weeks of age, thymocyte numbers are significantly reduced compared to wild-type mice but increased compared to homozygous mutants
decreased CD4-positive, alpha-beta T cell number ( J:100951 )
• the number of CD4+ cells is decreased at 6 weeks of age compared to wild-type mice but increased compared to homozygous mutants
decreased CD8-positive, alpha-beta T cell number ( J:100951 )
• the number of CD8+ cells is decreased at 6 weeks of age compared to wild-type mice but increased compared to homozygous mutants

endocrine/exocrine glands
decreased thymocyte number ( J:100951 )
• at E17.5, E19.5 and 6 weeks of age, thymocyte numbers are significantly reduced compared to wild-type mice but increased compared to homozygous mutants




Genotype
MGI:3845244
ht2
Allelic
Composition		 Pax1tm1Neu/Pax1+
Genetic
Background		 involves: 129S1/Sv * 129X1/SvJ * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Pax1tm1Neu mutation (0 available); any Pax1 mutation (26 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
skeleton
abnormal sternum morphology ( J:49339 )
• 88% of mice exhibit abnormalities in the first two cervical vertebrae, in the lumbar region, and/or the sternum
• 34% of mice exhibit ossification of intersternebra 5
abnormal vertebrae morphology ( J:49339 )
• 88% of mice exhibit abnormalities in the first two cervical vertebrae, in the lumbar region, and/or the sternum
abnormal cervical atlas morphology ( J:49339 )
• 63% of mice exhibit ventral fusion of the axis to the arcus of the atlas by cartilaginous bridge
abnormal ventral tubercle of atlas morphology ( J:49339 )
• the ventral tubercle of the arcus is enlarged
abnormal lumbar vertebrae morphology ( J:49339 )
• 44% of mice exhibit abnormalities in the lumbar region
• in most cases, L4 displays dual ossification centers unlike in wild-type mice
• in 3 of 32 mice, the pedicles fuse to one of the twin ossification centers and costal processes of the affected vertebrae are missing unlike in wild-type mice




Genotype
MGI:5635923
ht3
Allelic
Composition		 Pax1Un-s/Pax1+
Genetic
Background		 involves: CC57BR/MvY
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Pax1Un-s mutation (1 available); any Pax1 mutation (26 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
limbs/digits/tail
short tail ( J:13467 )
• short undulated tail
wavy tail ( J:13467 )
• short wavy tail




Genotype
MGI:3776838
cx4
Allelic
Composition		 Pax1un/Pax1+
Tcf3tm1Cmu/Tcf3tm1Cmu
Genetic
Background		 involves: 129P2/OlaHsd * C3H * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Pax1un mutation (6 available); any Pax1 mutation (26 available)
Tcf3tm1Cmu mutation (0 available); any Tcf3 mutation (48 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
mortality/aging
postnatal lethality, incomplete penetrance ( J:103567 )
• most mice die postnatally due to are cannibalization

reproductive system

nervous system
open neural tube ( J:103567 )
• mice are born with non-lethal neural tube defects at the lumbosacral region over which skin grows

renal/urinary system
abnormal renal/urinary system morphology ( J:103567 )
• mice exhibit high outflow tract resistance

immune system
abnormal T cell differentiation ( J:103567 )
• T cell transition to double positive is partially blocked
abnormal T cell subpopulation ratio ( J:103567 )
• the ratio of CD4 over CD8 T cells is reduced compared to in wild-type mice

limbs/digits/tail

hematopoietic system
abnormal T cell differentiation ( J:103567 )
• T cell transition to double positive is partially blocked
abnormal T cell subpopulation ratio ( J:103567 )
• the ratio of CD4 over CD8 T cells is reduced compared to in wild-type mice

embryo
open neural tube ( J:103567 )
• mice are born with non-lethal neural tube defects at the lumbosacral region over which skin grows

Mouse Models of Human Disease
 DO ID OMIM ID(s) Ref(s)
neural tube defect DOID:0080074 OMIM:301410
OMIM:601634
 J:103567




Genotype
MGI:4437579
cx5
Allelic
Composition		 kkt/kkt+
Pax1un/Pax1+
Genetic
Background		 involves: C57BL/6 * CBA
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
kkt mutation (0 available); any kkt mutation (0 available)
Pax1un mutation (6 available); any Pax1 mutation (26 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
skeleton
skeleton phenotype ( J:60410 )
N
• newborns exhibit a normal sternum; no fusion of the fourth and fifth sternebrae is observed, unlike in kkt or Pax1un homozygotes
small acromion ( J:60410 )
• newborns exhibit a severe reduction in the acromion of the scapula
abnormal axial skeleton morphology ( J:60410 )
• newborns display skeletal defects similar to those observed in Pax1un homozygotes, but milder than in kkt homozygotes, except for the split vertebral body seen in multiple vertebrae between L2 and L5
abnormal thoracic vertebrae morphology ( J:60410 )
• all newborns exhibit bilateral ossification centers in the lower thoracic vertebrae; however, the ossification centers are not fused to the pedicles, unlike in kkt homozygotes
abnormal lumbar vertebrae morphology ( J:60410 )
• all newborns exhibit bilateral ossification centers in the lumbar vertebrae
• ossification centers are only fused to the pedicles in the lower lumbar region
• a split vertebral body is observed in multiple vertebrae between L2 and L5, and this is far more severe than in either kkt or Pax1un homozygotes
• however, the transverse processes in L6 are all pointing forward, similar to those in wild-type control neonates
abnormal vertebral body morphology ( J:60410 )
• a split vertebral body is observed in L3, L4, and L5




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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
03/18/2025
MGI 6.24 		The Jackson Laboratory