Phenotypes associated with this allele

• Allele Symbol: Apbb1^tm1Her
• Allele Name: targeted mutation 1, Joachim Herz
• Allele ID: MGI:3615373
• Summary: 4 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Apbb1^tm1Her/Apbb1^tm1Her	involves: 129S6/SvEvTac * C57BL/6	MGI:3622752
cx2	Apbb1^tm1Her/Apbb1^tm1Her Apbb2^tm1Her/Apbb2^tm1Her	involves: 129S6/SvEvTac * C57BL/6	MGI:3622755
cx3	Apbb1^tm1Her/Apbb1^+ Apbb2^tm1Her/Apbb2^tm1Her	involves: 129S6/SvEvTac * C57BL/6	MGI:3622756
cx4	Apbb1^tm1Her/Apbb1^tm1Her Apbb2^tm1Her/Apbb2^+	involves: 129S6/SvEvTac * C57BL/6	MGI:3622757

Genotype
MGI:3622752

hm1

• Allelic Composition: Apbb1^tm1Her/Apbb1^tm1Her
• Genetic Background: involves: 129S6/SvEvTac * C57BL/6

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

normal phenotype

no abnormal phenotype detected ( J:105160 )

• homozygotes are viable and fertile with normal brain morphology

Genotype
MGI:3622755

cx2

• Allelic Composition: Apbb1^tm1Her/Apbb1^tm1Her; Apbb2^tm1Her/Apbb2^tm1Her
• Genetic Background: involves: 129S6/SvEvTac * C57BL/6

mortality/aging

postnatal lethality ( J:105160 )

• fewer than expected double homozygotes are found at P21, the expected numbers are found at E12.5-E16.5 and at E18.5-P0

nervous system

abnormal axon extension ( J:105160 )

• reduced size and medial shift of fimbria in coronal sections

• mossy fiber axons are absent from the infrapyramidal blade of the dentate gyrus

• ectopic axon bundles of thalamic origin are found in adult and embryonic brains apparently directed towards the ectopic cell clusters

• at E16.5, fewer thalamocortical axon fibers are seen in the intermediate zone and fewer fibers leaving the intermediate zone to enter the internal capsule

abnormal telencephalon development ( J:105160 )

• at E14.5, E16.5, and E18.5 clusters of ectopic cells are seen on the neocortical surface often associated with streams of migrating cells directed towards the ectopic cluster

• however, at E12.5 no ectopic cells are seen in the preplate

• these ectopic cells appear to be radially migrating neuroepithelial cells

abnormal cortical marginal zone morphology ( J:105160 )

• at E14.5 and E18.5, Cajal-Retzius cells are displaced by ectopic cells but no substantial loss of these cells is seen

absent corpus callosum ( J:105160 )

• agenesis of the corpus callosum is seen in all homozygotes at E18.5 and in adults

• Probst bundles are seen in many adult homozygotes

abnormal dentate gyrus morphology ( J:105160 )

• the infrapyramidal blade of the dentate gyrus is foreshortened, deflected towards the thalamus, and lacks mossy fiber axons

abnormal cerebral cortex morphology ( J:105160 )

• focal heterotopias are found layer 1 of the cortex, but not in the cerebellum or olfactory bulb

• penetrance of heterotopias is 100%

abnormal frontal lobe morphology ( J:105160 )

• focal heterotopias are found in the frontal cortex

abnormal parietal lobe morphology ( J:105160 )

• focal heterotopias are found in the parietal cortex

abnormal meninges morphology ( J:105160 )

• meningeal fibroblasts have reduced punctate laminin, lack fibrillar laminin at the cell periphery, and fewer but thicker F-actin fibers

• however, no menigeal fibrosis is seen

abnormal brain pia mater morphology ( J:105160 )

• areas of the marginal zone containing ectopic cells have disrupted pial basement membranes with reduced and disrupted chondroitin sulfate proteoglycan and laminin staining

growth/size/body

decreased body size ( J:105160 )

• viable double homozygotes are smaller than their littermates

cellular

abnormal axon extension ( J:105160 )

• reduced size and medial shift of fimbria in coronal sections

• mossy fiber axons are absent from the infrapyramidal blade of the dentate gyrus

• ectopic axon bundles of thalamic origin are found in adult and embryonic brains apparently directed towards the ectopic cell clusters

• at E16.5, fewer thalamocortical axon fibers are seen in the intermediate zone and fewer fibers leaving the intermediate zone to enter the internal capsule

Genotype
MGI:3622756

cx3

• Allelic Composition: Apbb1^tm1Her/Apbb1⁺; Apbb2^tm1Her/Apbb2^tm1Her
• Genetic Background: involves: 129S6/SvEvTac * C57BL/6

normal phenotype

no abnormal phenotype detected ( J:105160 )

• mice with 3 mutant alleles are viable and fertile with normal brain morphology

Genotype
MGI:3622757

cx4

• Allelic Composition: Apbb1^tm1Her/Apbb1^tm1Her; Apbb2^tm1Her/Apbb2⁺
• Genetic Background: involves: 129S6/SvEvTac * C57BL/6

normal phenotype

no abnormal phenotype detected ( J:105160 )

• mice with 3 mutant alleles are viable and fertile with normal brain morphology