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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID 		Brca1+
wild type
MGI:2152435
Summary 8 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
ht1
 		Brca1tm1Bhk/Brca1+ C.129P2-Brca1tm1Bhk MGI:5517368
ht2
 		Brca1tm1Mak/Brca1+ either: (involves: 129P2/OlaHsd * C3H/HeJ) or (involves: 129P2/OlaHsd * C57BL/6J) or (involves: 129P2/OlaHsd * CD-1) MGI:2174686
ht3
 		Brca1tm1Bhk/Brca1+ involves: 129P2/OlaHsd * C57BL/6 * DBA/2 MGI:2174677
ht4
 		Brca1tm1Whl/Brca1+ involves: 129P2/OlaHsd * C57BL/6J MGI:2174688
ht5
 		Brca1tm1Arge/Brca1+ involves: 129S/SvEv * C57BL/6 MGI:2174675
cn6
 		Brca1tm1Brn/Brca1+
Trp53tm1Brn/Trp53tm1Brn
Tg(KRT14-cre)8Brn/0 		involves: 129P2/OlaHsd * BALB/cJ * FVB/N MGI:3762186
cx7
 		Brca1tm1Bhk/Brca1+
Cdkn2ctm1Yxi/Cdkn2ctm1Yxi 		C.129-Cdkn2ctm1Yxi Brca1tm1Bhk MGI:5517370
cx8
 		Brca1tm2Cxd/Brca1+
Tg(KRT5-E2F1)2Dgj/0 		involves: 129S6/SvEvTac * C57BL/6 * SJL MGI:3836053


Genotype
MGI:5517368
ht1
Allelic
Composition		 Brca1tm1Bhk/Brca1+
Genetic
Background		 C.129P2-Brca1tm1Bhk
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Bhk mutation (0 available); any Brca1 mutation (113 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
cellular
decreased mammary gland epithelial cell proliferation ( J:198018 )
• cellular proliferation is inhibited in young and old mammary epithelial cells

endocrine/exocrine glands
decreased mammary gland epithelial cell proliferation ( J:198018 )
• cellular proliferation is inhibited in young and old mammary epithelial cells
increased mammary gland tumor incidence ( J:198018 )
• less than 10% of mutants develop mammary tumors

growth/size/body
decreased body weight ( J:198018 )
• decrease in body weight from 12 to 24 weeks of age

integument
decreased mammary gland epithelial cell proliferation ( J:198018 )
• cellular proliferation is inhibited in young and old mammary epithelial cells
increased mammary gland tumor incidence ( J:198018 )
• less than 10% of mutants develop mammary tumors

neoplasm
increased mammary gland tumor incidence ( J:198018 )
• less than 10% of mutants develop mammary tumors




Genotype
MGI:2174686
ht2
Allelic
Composition		 Brca1tm1Mak/Brca1+
Genetic
Background		 either: (involves: 129P2/OlaHsd * C3H/HeJ) or (involves: 129P2/OlaHsd * C57BL/6J) or (involves: 129P2/OlaHsd * CD-1)
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Mak mutation (0 available); any Brca1 mutation (113 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
normal phenotype
no abnormal phenotype detected ( J:33880 )
• no obvious phenotype up to 11 months of age




Genotype
MGI:2174677
ht3
Allelic
Composition		 Brca1tm1Bhk/Brca1+
Genetic
Background		 involves: 129P2/OlaHsd * C57BL/6 * DBA/2
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Bhk mutation (0 available); any Brca1 mutation (113 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
normal phenotype
no abnormal phenotype detected ( J:31571 )
• no aberrant phenotype is seen up to 5 months of age




Genotype
MGI:2174688
ht4
Allelic
Composition		 Brca1tm1Whl/Brca1+
Genetic
Background		 involves: 129P2/OlaHsd * C57BL/6J
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Whl mutation (0 available); any Brca1 mutation (113 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
normal phenotype
no abnormal phenotype detected ( J:34458 )
• no obvious phenotype up to 10 months of age




Genotype
MGI:2174675
ht5
Allelic
Composition		 Brca1tm1Arge/Brca1+
Genetic
Background		 involves: 129S/SvEv * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Arge mutation (0 available); any Brca1 mutation (113 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
normal phenotype
no abnormal phenotype detected ( J:40594 )
• up to 15 months of age; in particular, no tumors are detected




Genotype
MGI:3762186
cn6
Allelic
Composition		 Brca1tm1Brn/Brca1+
Trp53tm1Brn/Trp53tm1Brn
Tg(KRT14-cre)8Brn/0
Genetic
Background		 involves: 129P2/OlaHsd * BALB/cJ * FVB/N
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Brn mutation (2 available); any Brca1 mutation (113 available)
Tg(KRT14-cre)8Brn mutation (3 available)
Trp53tm1Brn mutation (20 available); any Trp53 mutation (237 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
neoplasm
increased mammary gland tumor incidence ( J:126551 )
• mice develop mammary gland with a latency of 332 days

integument
increased mammary gland tumor incidence ( J:126551 )
• mice develop mammary gland with a latency of 332 days

endocrine/exocrine glands
increased mammary gland tumor incidence ( J:126551 )
• mice develop mammary gland with a latency of 332 days

Mouse Models of Human Disease
 DO ID OMIM ID(s) Ref(s)
breast cancer DOID:1612 OMIM:114480
 J:126551




Genotype
MGI:5517370
cx7
Allelic
Composition		 Brca1tm1Bhk/Brca1+
Cdkn2ctm1Yxi/Cdkn2ctm1Yxi
Genetic
Background		 C.129-Cdkn2ctm1Yxi Brca1tm1Bhk
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm1Bhk mutation (0 available); any Brca1 mutation (113 available)
Cdkn2ctm1Yxi mutation (1 available); any Cdkn2c mutation (14 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
endocrine/exocrine glands
abnormal mammary gland morphology ( J:198018 )
• mammary glands of virgin females show a decrease in the expansion of luminal progenitors seen in single Cdkn2c homozygotes to normal levels but show an increase in the expansion of basal/myoepithelial cells
increased mammary gland tumor incidence ( J:198018 )
• 38% of mutants develop breast cancer before 1 year of age and 87% by 22 months of age
• mammary tumors show high degree of heterogeneity, increased population of CK5+ cells, loss of wild-type allele of Brca1 in CK5+ tumor cells, ERalpha negativity and invasiveness and metastasis
• mammary tumors are transformed from a luminal subtype that is seen in single Cdkn2c homozygotes into a basal-like subtype
increased mammary adenocarcinoma incidence ( J:198018 )
• poorly differentiated carcinoma with squamous metaplasia

integument
abnormal mammary gland morphology ( J:198018 )
• mammary glands of virgin females show a decrease in the expansion of luminal progenitors seen in single Cdkn2c homozygotes to normal levels but show an increase in the expansion of basal/myoepithelial cells
increased mammary gland tumor incidence ( J:198018 )
• 38% of mutants develop breast cancer before 1 year of age and 87% by 22 months of age
• mammary tumors show high degree of heterogeneity, increased population of CK5+ cells, loss of wild-type allele of Brca1 in CK5+ tumor cells, ERalpha negativity and invasiveness and metastasis
• mammary tumors are transformed from a luminal subtype that is seen in single Cdkn2c homozygotes into a basal-like subtype
increased mammary adenocarcinoma incidence ( J:198018 )
• poorly differentiated carcinoma with squamous metaplasia

neoplasm
increased mammary gland tumor incidence ( J:198018 )
• 38% of mutants develop breast cancer before 1 year of age and 87% by 22 months of age
• mammary tumors show high degree of heterogeneity, increased population of CK5+ cells, loss of wild-type allele of Brca1 in CK5+ tumor cells, ERalpha negativity and invasiveness and metastasis
• mammary tumors are transformed from a luminal subtype that is seen in single Cdkn2c homozygotes into a basal-like subtype
increased mammary adenocarcinoma incidence ( J:198018 )
• poorly differentiated carcinoma with squamous metaplasia
increased metastatic potential ( J:198018 )
• 4 of 13 (31%) mammary tumors metastasize to the lung and blood vessels after 1 year of age

Mouse Models of Human Disease
 DO ID OMIM ID(s) Ref(s)
breast cancer DOID:1612 OMIM:114480
 J:198018




Genotype
MGI:3836053
cx8
Allelic
Composition		 Brca1tm2Cxd/Brca1+
Tg(KRT5-E2F1)2Dgj/0
Genetic
Background		 involves: 129S6/SvEvTac * C57BL/6 * SJL
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Brca1tm2Cxd mutation (3 available); any Brca1 mutation (113 available)
Tg(KRT5-E2F1)2Dgj mutation (0 available)
♀ phenotype observed in females
♂ phenotype observed in males
N normal phenotype
neoplasm
increased tumor incidence ( J:85354 )
• mutants develop tumors after 1 year of age and by 70 weeks, 50% of mutants have tumors
increased skin tumor incidence ( J:85354 )
• majority of tumors occur in the skin
increased squamous cell carcinoma incidence ( J:85354 )
• majority of tumors are squamous cell carcinoma

integument
increased keratinocyte proliferation ( J:85354 )
• increase in basal keratinocyte proliferation
abnormal epidermal layer morphology ( J:85354 )
• mutants exhibit increased epidermal proliferation and apoptosis
increased skin tumor incidence ( J:85354 )
• majority of tumors occur in the skin

cellular
increased keratinocyte proliferation ( J:85354 )
• increase in basal keratinocyte proliferation




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)
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Send questions and comments to User Support. 		last database update
01/06/2026
MGI 6.24 		The Jackson Laboratory