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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID
Rb1tm2Mlh
targeted mutation 2, Martin L Hooper
MGI:1857341
Summary 2 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
hm1
Rb1tm2Mlh/Rb1tm2Mlh either: 129P2/OlaHsd-Rb1tm2Mlh or (involves: 129P2/OlaHsd * BALB/c) or (involves: 129P2/OlaHsd * FVB/N) MGI:3574051
ht2
Rb1tm2Mlh/Rb1+ either: 129P2/OlaHsd-Rb1tm2Mlh or (involves: 129P2/OlaHsd * BALB/c) or (involves: 129P2/OlaHsd * FVB/N) MGI:3574052


Genotype
MGI:3574051
hm1
Allelic
Composition
Rb1tm2Mlh/Rb1tm2Mlh
Genetic
Background
either: 129P2/OlaHsd-Rb1tm2Mlh or (involves: 129P2/OlaHsd * BALB/c) or (involves: 129P2/OlaHsd * FVB/N)
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Rb1tm2Mlh mutation (0 available); any Rb1 mutation (111 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• homozygotes die in utero; resorptions are already present at E10.5-E12.5, suggesting that embryonic lethality may occur prior to these stages

hematopoietic system
• homozygotes exhibit a failure of hematopoiesis in liver cultures
• in some cases, E12.5 homozygotes show an increase in myeloid cell numbers relative to wild-type mice
• in some cases, E12.5 homozygotes show an increase in liver megakaryocyte levels relative to wild-type mice
• at E12.5, mutant red cells have more densely stained cytoplasm of reduced volume and pyknotic nuclei that are in some cases irregular
• homozygotes display abnormal erythrocytes in fetal blood, loss of mature nucleated red cells in the yolk sac vessels, and abnormal proliferation of immature erythrocytes in the liver (J:2498)
• at E13.5, homozygotes synthesize normal levels of adult beta-globin chains, suggesting normal hemoglobin chain switching; thus, abnormal production of nucleated erythrocytes occurs only during fetal liver erythropoiesis (J:20542)
• at E12.5, homozygotes display a lower ratio of red to white blood cells relative to wild-type

nervous system
• homozygotes have a more prominent fourth ventricle relative to wild-type mice (variable penetrance)
• homozygotes display a significantly smaller frontal lobe relative to wild-type embryos (variable penetrance)
• at E11.5, homozygotes exhibit numerous apoptotic cells in the spinal ganglia, identified by their pyknotic and fragmented nuclei and dense eosinophilic cytoplasm
• at ~E14.5, homozygous mutant embryos display massive degeneration of the developing CNS (J:20542)

craniofacial
• homozygotes display a compressed forehead relative to wild-type mice (variable penetrance)

embryo
• at E12.5, 11 out of 17 mutant embryos resemble wild-type embryos of an earlier embryonic stage, suggesting developmental retardation (variable penetrance)
• at E12.5, 11 out of 17 homozygotes have a pale appearance (variable penetrance)
• mutant yolk sac membranes are thinner with empty capillaries and fewer red cells relative to wild-type

cellular
• at E11.5, mutant embryos exhibit increased apoptosis in the spinal cord, myelencephalon, pontine flexure, and particularly in the spinal ganglia; in 1 out of 17 embyos, degeneration extends into the prosencephalon
• increased cell death is specifically noted in the intermediate zone (but not in the ventriculate zone) with ectopic mitosis

growth/size/body
• homozygotes display a compressed forehead relative to wild-type mice (variable penetrance)
• at E12.5, 11 out of 17 mutant embryos resemble wild-type embryos of an earlier embryonic stage, suggesting developmental retardation (variable penetrance)

liver/biliary system
• at E11.5, mutant livers show abnormal trabecular structure with dilated sinusoids containing red cells, some of which are irregular and some apoptotic
• the mutant fetal liver displays reduced cellularilty relative to wild-type

immune system
• in some cases, E12.5 homozygotes show an increase in myeloid cell numbers relative to wild-type mice

vision/eye
N
• in homozygotes, retinal development occurs normally at least until E14.5
• as early as E14.5, homozygous mutant lenses show abnormal fiber cell differentiation

cardiovascular system
• at E11.5, mutant livers show abnormal trabecular structure with dilated sinusoids containing red cells, some of which are irregular and some apoptotic




Genotype
MGI:3574052
ht2
Allelic
Composition
Rb1tm2Mlh/Rb1+
Genetic
Background
either: 129P2/OlaHsd-Rb1tm2Mlh or (involves: 129P2/OlaHsd * BALB/c) or (involves: 129P2/OlaHsd * FVB/N)
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Rb1tm2Mlh mutation (0 available); any Rb1 mutation (111 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
neoplasm
N
• up to 7 months of age, young heterozygotes exhibit no sign of retinoblastoma or any other abnormality relative to wild-type mice (J:2498)
• no retinoblastomas are macroscopically detected in chimeras ranging in age up to 11 months (J:2498)
• no pre-neoplastic lesions are detected in the medulla of the adrenal gland of heterozygous mutant mice (J:20542)
• after 3-5 months, heterozygotes develop large (4-5 mm) tumors in the intermediate lobe of the pituitary gland
• such tumors are relatively benign and do not infiltrate into brain tissue; the wild-type allele of Rb1 is lost in the vast majority of cases

nervous system
• after 3-5 months, heterozygotes develop large (4-5 mm) tumors in the intermediate lobe of the pituitary gland
• such tumors are relatively benign and do not infiltrate into brain tissue; the wild-type allele of Rb1 is lost in the vast majority of cases
• at E11.5, heterozygotes exhibit only occasional apoptotic cells in the spinal ganglia, identified by their pyknotic and fragmented nuclei and dense eosinophilic cytoplasm

endocrine/exocrine glands
• after 3-5 months, heterozygotes develop large (4-5 mm) tumors in the intermediate lobe of the pituitary gland
• such tumors are relatively benign and do not infiltrate into brain tissue; the wild-type allele of Rb1 is lost in the vast majority of cases





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last database update
10/29/2024
MGI 6.24
The Jackson Laboratory