Phenotypes associated with this allele

• Allele Symbol: Robo2^tm1Mrt
• Allele Name: targeted mutation 1, Gail R Martin
• Allele ID: MGI:3043127
• Summary: 7 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Robo2^tm1Mrt/Robo2^tm1Mrt	involves: 129P2/OlaHsd	MGI:5522717
hm2	Robo2^tm1Mrt/Robo2^tm1Mrt	involves: 129P2/OlaHsd * 129/Sv * C57BL/6 * CD-1	MGI:3043154
hm3	Robo2^tm1Mrt/Robo2^tm1Mrt	involves: 129P2/OlaHsd * C57BL/6	MGI:5522686
hm4	Robo2^tm1Mrt/Robo2^tm1Mrt	Not Specified	MGI:3043185
cx5	Robo1^tm1Matl/Robo1^tm1Matl Robo2^tm1Mrt/Robo2^tm1Mrt	involves: 129P2/OlaHsd	MGI:5470528
cx6	Robo1^tm1Matl/Robo1^tm1Matl Robo2^tm1Mrt/Robo2^tm1Mrt	involves: 129P2/OlaHsd * C57BL/6 * CD-1	MGI:5522691
cx7	Robo2^tm1Mrt/Robo2^tm1Mrt Robo3^tm1Matl/Robo3^tm1Matl	involves: 129/Sv * CD-1	MGI:3043210

Genotype
MGI:5522717

hm1

• Allelic Composition: Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: involves: 129P2/OlaHsd

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

nervous system

abnormal olfactory tract morphology ( J:119469 )

• thinner and spread along the ventrolateral surface of the telencephalon at E18

Genotype
MGI:3043154

hm2

• Allelic Composition: Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: involves: 129P2/OlaHsd * 129/Sv * C57BL/6 * CD-1

mortality/aging

postnatal lethality, complete penetrance ( J:90324 )

• almost all homozygotes fail to survive after birth

renal/urinary system

abnormal ureter morphology ( J:90324 )

• multiple ureters arising from a single kidney are seen with 6/14 kidneys having 3 ureters, 6/14 having 2 ureters, and 2 having only 1 ureter

• most of the ureters remain connected to the nephric duct rather than undergoing remodeling to connect to the bladder

Genotype
MGI:5522686

hm3

• Allelic Composition: Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6

nervous system

abnormal cerebellar peduncle morphology ( J:120131 )

• appears to be ventrally displaced and corticofugal axons abnormally defasciculate in some mice at E18.5

abnormal innervation ( J:120131 )

• at E18.5, a few corticofugal axons are ventrally displaced reaching the ventral midline at the level of the anterior commissure and occasional bundles of cortical fibers are found in the dorsal thalamus

• at E18.5, some thalamocortical fibers fail to reach the telencephalon and instead grow toward the ventral diencephalon and invade the hypothalamu

Genotype
MGI:3043185

hm4

• Allelic Composition: Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: Not Specified

nervous system

abnormal axon guidance ( J:89780 )

• commissural axons remain tightly apposed to the floor plate rather than moving into more dorsal longitudinal tracts

abnormal spinal cord lateral column morphology ( J:89780 )

• the lateral funiculus (white matter tract) is foreshortened in homozygous mutants compared to wild-type mice as a result of abnormal commissural axon growth

cellular

abnormal axon guidance ( J:89780 )

• commissural axons remain tightly apposed to the floor plate rather than moving into more dorsal longitudinal tracts

Genotype
MGI:5470528

cx5

• Allelic Composition: Robo1^tm1Matl/Robo1^tm1Matl; Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: involves: 129P2/OlaHsd

mortality/aging

neonatal lethality, complete penetrance ( J:193400 )

• die within minutes of birth

homeostasis/metabolism

cyanosis ( J:193400 )

respiratory system

short trachea ( J:193400 )

• slightly shorter

respiratory failure ( J:193400 )

• lungs fail to inflate

nervous system

abnormal axon guidance ( J:119469 )

• olfactory bulb axons from E14 explants are not repelled by SLIT proteins

abnormal olfactory tract morphology ( J:119469 )

• highly defasciculated into small axonal bundles fanned all over the ventral side of the telencephalon, at E15.5 and E18

• a subset of axons originating from the lateral bulb are still present in the normal location

abnormal spinal cord ventral commissure morphology ( J:194150 )

• at E11.5, commissural axons exhibit robust postcrossing trajectory defects with failure to project to the lateral portion of the funiculus and altered lateral and ventral funiculi ration compared with wild-type mice

cellular

abnormal axon guidance ( J:119469 )

• olfactory bulb axons from E14 explants are not repelled by SLIT proteins

decreased cell migration ( J:193400 )

• in culture, fewer E10.5 foregut cells migrate away from SLIT2 containing media

digestive/alimentary system

abnormal stomach position or orientation ( J:193400 )

• mispositioning of the stomach in the thoracic instead of the abdominal cavity

• abnormal midline position detected as early as E11.5

• more prominent at E13.5 and disrupts the diaphragm

• located at the midline and protrudes through the esophageal hiatus into the thoracic cavity in neonates

abnormal foregut morphology ( J:193400 )

• delayed separation of the foregut from the body wall

small esophagus ( J:193400 )

• short

esophagus hypoplasia ( J:193400 )

muscle

abnormal diaphragm morphology ( J:193400 )

• malformed

behavior/neurological

absent gastric milk in neonates ( J:193400 )

cardiovascular system

abnormal dorsal aorta morphology ( J:193400 )

• fails to fuse by E11.5

Genotype
MGI:5522691

cx6

• Allelic Composition: Robo1^tm1Matl/Robo1^tm1Matl; Robo2^tm1Mrt/Robo2^tm1Mrt
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6 * CD-1

cellular

abnormal axon guidance ( J:120131 )

nervous system

abnormal axon guidance ( J:120131 )

abnormal dorsal telencephalic commissure morphology ( J:120131 )

• two large ectopic fiber bundles formed of corticocortical axons are seen on either side of the corpus callosum at E18.5

decreased corpus callosum size ( J:120131 )

• at E18.5

abnormal anterior commissure morphology ( J:120131 )

• displaced dorsally due to the presence of ectopic fiber bundles

abnormal innervation ( J:120131 )

• large bundles of ectopic fibers are seen crossing the ventral midline at the level of the anterior commissure and in the basal telencephalon at E18.5

• most corticofugal axons are diverted toward the midline

• only a few cortical axons reach the dorsal thalamus and those that do follow a more ventral trajectory

• virtually no corticospinal axons reach the diencephalon

• many thalamic axons abnormally invade the hypothalamus

Genotype
MGI:3043210

cx7

• Allelic Composition: Robo2^tm1Mrt/Robo2^tm1Mrt; Robo3^tm1Matl/Robo3^tm1Matl
• Genetic Background: involves: 129/Sv * CD-1

nervous system

abnormal axon guidance ( J:89438 )

• at E11.5 embryos show no midline crossing and look identical to Robo3^tm1Matl homozygous littermates

cellular

abnormal axon guidance ( J:89438 )

• at E11.5 embryos show no midline crossing and look identical to Robo3^tm1Matl homozygous littermates