Phenotypes associated with this allele

• Allele Symbol: Nrg1^tm2Cbm
• Allele Name: targeted mutation 2, Carmen Birchmeier
• Allele ID: MGI:1928490
• Summary: 3 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Nrg1^tm2Cbm/Nrg1^tm2Cbm	involves: 129P2/OlaHsd	MGI:2173313
hm2	Nrg1^tm2Cbm/Nrg1^tm2Cbm	involves: 129P2/OlaHsd * C57BL/6	MGI:2175172
ht3	Nrg1^tm2Cbm/Nrg1^+	involves: 129P2/OlaHsd	MGI:3835557

Genotype
MGI:2173313

hm1

• Allelic Composition: Nrg1^tm2Cbm/Nrg1^tm2Cbm
• Genetic Background: involves: 129P2/OlaHsd

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

nervous system

decreased Schwann cell number ( J:43309 )

• reduced number of Schwann cell precursors that line the spinal nerves of the trunk, indicating that type III neuregulin is necessary and sufficient for Schwann cell precursor development

abnormal sympathetic ganglion morphology ( J:48515 )

• lack neural crest cell precursor cells in the anlage of the primary sympathetic ganglion chain

embryo

abnormal neural crest cell migration ( J:48515 )

• severe reduction in the numbers of neural crest cells that migrate to the dorsal aorta

cellular

decreased Schwann cell number ( J:43309 )

• reduced number of Schwann cell precursors that line the spinal nerves of the trunk, indicating that type III neuregulin is necessary and sufficient for Schwann cell precursor development

abnormal neural crest cell migration ( J:48515 )

• severe reduction in the numbers of neural crest cells that migrate to the dorsal aorta

Genotype
MGI:2175172

hm2

• Allelic Composition: Nrg1^tm2Cbm/Nrg1^tm2Cbm
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6

mortality/aging

embryonic lethality during organogenesis, complete penetrance ( J:29971 )

• all mutant embryos die by E11.5

cardiovascular system

trabecula carnea hypoplasia ( J:29971 )

• however, atria were morphologically normal

failure of atrioventricular cushion closure ( J:29971 )

• at E10.5, the endocardial cusion was not closed, and the mesenchymal cells forming the cusion were reduced in number

enlarged heart ( J:29971 )

• frequently observed

enlarged pericardium ( J:29971 )

• frequently observed

irregular heartbeat ( J:29971 )

muscle

trabecula carnea hypoplasia ( J:29971 )

• however, atria were morphologically normal

nervous system

decreased Schwann cell precursor number ( J:29971 )

• Schwann cell precursors in the trunk appear reduced in number

abnormal cranial ganglia morphology ( J:29971 )

• cranial ganglia cells are reduced in number

• distinct ganglia are altered to different extents

• geniculate and vestibular-cochlea ganglia appear unaffected

• loss of neural-crest derived cells in the ganglia are thought to account for the morphological changes

small petrosal ganglion ( J:29971 )

• projections are disorganized; projections to CNS often absent

small nodose ganglion ( J:29971 )

• projections are disorganized

abnormal superior vagus ganglion morphology ( J:29971 )

• the jugular ganglion is described as abnormal

abnormal cranial nerve morphology ( J:29971 )

• cranial nerves are severely altered, whereas other peripheral projections appear normal

abnormal mandibular nerve innervation pattern ( J:29971 )

• mandibular projections and axonal connections between trigeminus and hindbrain are lost

absent trigeminal nerve ( J:29971 )

• lost, particularly the dorsal part

growth/size/body

enlarged heart ( J:29971 )

• frequently observed

cellular

decreased Schwann cell precursor number ( J:29971 )

• Schwann cell precursors in the trunk appear reduced in number

Genotype
MGI:3835557

ht3

• Allelic Composition: Nrg1^tm2Cbm/Nrg1⁺
• Genetic Background: involves: 129P2/OlaHsd

nervous system

nervous system phenotype ( J:145464 )

N • thickness of the myelin sheath in the central nervous system is normal