Phenotypes associated with this allele

• Allele Symbol: Hoxb4^tm1Bay
• Allele Name: targeted mutation 1, Baylor College of Medicine
• Allele ID: MGI:1857390
• Summary: 5 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Hoxb4^tm1Bay/Hoxb4^tm1Bay	129S/SvEv-Hoxb4^tm1Bay	MGI:2673173
hm2	Hoxb4^tm1Bay/Hoxb4^tm1Bay	involves: 129S7/SvEvBrd * C57BL/6J	MGI:2673171
cx3	Hoxb4^tm1Bay/Hoxb4^tm1Bay Hoxd4^tm1Bhr/Hoxd4^tm1Bhr	involves: 129S/SvEv	MGI:3611053
cx4	Hoxa4^tm1Bhr/Hoxa4^tm1Bhr Hoxb4^tm1Bay/Hoxb4^tm1Bay Hoxd4^tm1Bhr/Hoxd4^tm1Bhr	involves: 129S/SvEv	MGI:3611055
cx5	Hoxa4^tm1Bhr/Hoxa4^tm1Bhr Hoxb4^tm1Bay/Hoxb4^tm1Bay	involves: 129S7/SvEvBrd * C57BL/6	MGI:3611204

Genotype
MGI:2673173

hm1

• Allelic Composition: Hoxb4^tm1Bay/Hoxb4^tm1Bay
• Genetic Background: 129S/SvEv-Hoxb4^tm1Bay

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

mortality/aging

neonatal lethality, complete penetrance ( J:4612 )

• Background Sensitivity: on a co-isogenic background, 100% of homozygotes die within 1 day of birth; in contrast, on a mixed genetic background involving 129S7/SvEvBrd and C57BL/6J, 50% of homozygotes die perinatally while the remaining 50% survive to adulthood

skeleton

abnormal sternebra morphology ( J:4612 )

• all newborn homozygotes exhibit duplicated sternebrae as a result of a longitudinally split sternum

split sternum ( J:4612 )

• 100% of newborn homozygotes display a completely slit sternum

• a longitudinally split sternum is observed at all stages examined from E14.5 onward

abnormal cervical axis morphology ( J:4612 )

• only 1 of 3 newborn homozygotes show an extra ventral tubercle on the cervical axis (C2)

cervical vertebral transformation ( J:4612 )

• only 1 of 3 newborn homozygotes show a partial anterior homeotic transformation of the cervical axis (C2) to atlas (C1)

Genotype
MGI:2673171

hm2

• Allelic Composition: Hoxb4^tm1Bay/Hoxb4^tm1Bay
• Genetic Background: involves: 129S7/SvEvBrd * C57BL/6J

mortality/aging

decreased survivor rate ( J:4612 )

• only 50% of homozygotes survive to adulthood

prenatal lethality, incomplete penetrance ( J:4612 )

• Background Sensitivity: on a mixed genetic background involving 129S7/SvEvBrd and C57BL/6J, only 50% of the expected number of homozygotes are recovered at weaning with no deaths noted after P1-P2, suggesting that 50% of homozygotes die shortly after birth or during development; in contrast, on a co-isogenic background, 100% of homozygotes die within 1 day of birth

growth/size/body

abnormal chest morphology ( J:4612 )

• some homozygotes exhibit a concave chest

decreased body size ( J:4612 )

• surviving adult homozygotes are smaller than normal in size but remain healthy

skeleton

abnormal sternebra morphology ( J:4612 )

• homozygotes show variable defects in the fusion of paired sternal rudiments, resulting in partial or completely duplicated sternebrae

• phenotype ranges from a normal or a mildly affected sternum in surviving adult homozygotes to a completely split sternum in homozygotes that die early

split sternum ( J:4612 )

• a completely split sternum is observed in homozygotes that die early

abnormal cervical axis morphology ( J:4612 )

• some homozygotes display a partial anterior homeotic transformation of the second cervical vertebra or axis (C2) to atlas (C1)

• an ectopic ventral tubercle is observed on C2, along with a broadened neural arch

• in contrast, the dens and vertebral body appear unaffected

cervical vertebral transformation ( J:4612 )

• some homozygotes display a partial anterior homeotic transformation of the second cervical vertebra or axis (C2) to atlas (C1)

• a C3 to C2 transformation is rarely observed at the neural arch level

muscle

diaphragmatic hernia ( J:4612 )

• some homozygotes display hernias in the retrosternal part of the diaphragm involving the liver (most cases) or intestine (3 of 25)

Genotype
MGI:3611053

cx3

• Allelic Composition: Hoxb4^tm1Bay/Hoxb4^tm1Bay; Hoxd4^tm1Bhr/Hoxd4^tm1Bhr
• Genetic Background: involves: 129S/SvEv

mortality/aging

postnatal lethality, incomplete penetrance ( J:27467 )

• most homozygotes die within the first week of life but small numbers survive past six months

skeleton

abnormal cervical vertebrae morphology ( J:27467 )

• neural arches of C1 and C2 are often fused

cervical vertebral transformation ( J:27467 )

• almost complete C2 to C1 transformation

• C3 to C1 and C3 to C2 transformations

• C6 to C5 and C7 to C6 transformations

fusion of vertebral arches ( J:27467 )

• neural arches of C1 and C2 are often fused

Genotype
MGI:3611055

cx4

• Allelic Composition: Hoxa4^tm1Bhr/Hoxa4^tm1Bhr; Hoxb4^tm1Bay/Hoxb4^tm1Bay; Hoxd4^tm1Bhr/Hoxd4^tm1Bhr
• Genetic Background: involves: 129S/SvEv

skeleton

abnormal cervical vertebrae morphology ( J:27467 )

• atlas like anterior arches on C1 through C5

• lateral foramina on C2, C3, and C4

cervical vertebral transformation ( J:27467 )

• C6 to C5 and C7 to C6 transformations

Genotype
MGI:3611204

cx5

• Allelic Composition: Hoxa4^tm1Bhr/Hoxa4^tm1Bhr; Hoxb4^tm1Bay/Hoxb4^tm1Bay
• Genetic Background: involves: 129S7/SvEvBrd * C57BL/6

mortality/aging

postnatal lethality, complete penetrance ( J:27467 )

• died within the first week of life

skeleton

abnormal cervical vertebrae morphology ( J:27467 )

• loss of lateral articulations between C2 and C3

• large processus spinosi on both C2 and C3

• C7 rib found in Hoxa4^tm1Bhr single homozygotes is not found

• anterior tuberculi shifted from C6 to C7

cervical vertebral fusion ( J:27467 )

• fusions of C2 and C3