About   Help   FAQ
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





Contributing Projects:
Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO)
Citing These Resources
Funding Information
Warranty Disclaimer, Privacy Notice, Licensing, & Copyright
Send questions and comments to User Support.
last database update
11/12/2024
MGI 6.24
The Jackson Laboratory