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Phenotypes Associated with This Genotype
involves: 129S1/Sv * 129X1/SvJ * ICR
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Hap1tm1Hay mutation (0 available); any Hap1 mutation (22 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
• although homozygotes are born at the expected Mendelian frequency, >70% die within 2 days of birth primarily due to diminished feeding and malnutrition
• no homozygotes survive beyond 8 days of life

• by P2, homozygotes display an obvious decrease in feeding behavior, despite normal balance and motor coordination at P1-P6 and a normal suckling behavior at P1-P4
• feeding, weight gain and survival can not be improved by trimming the litter between P1-P2 to remove almost all of competing control littermates
• other physiological processes including sensitivity to tactile stimuli and mild pain remain normal
• by P2, homozygotes contain little to no milk in their stomachs

• at P1, homozygotes are slightly smaller than wild-type and heterozygous littermates
• by P3, live homozygotes are dramatically smaller than control littermates
• at P1, >94% of homozygous mutant pups weigh less than 1.60 g, whereas 44% of wild-type and 48% of heterozygous controls weigh more than 1.60 g
• however, no gross anatomical abnormalities are noted in the heart, liver, lungs, adrenal gland or kidney
• by P3, homozygous mutant pups gain weight daily at a significantly lower rate than wild-type or heterozygous pups
• by P5, homozygous mutant pups weigh on average 30-40% less than control littermates

nervous system
• at P8, homozygous mutant brains are proportionately smaller than those of heterozygous controls
• at P8, homozygous mutant brains weigh 30% less than those of heterozygous controls
• at P8, mutant brains display notable inward depressions in both hemispheres of the cortical mantel, extending from the somatosensory cortex to the parietal associated cortex, auditory cortex and visual cortex
• a 1.75- and 1.4-fold increase in neuronal density is observed in cortical layer V and II, respectively, relative to controls; however, the thickness of cortical layer I, which contains axons from pyramidal neurons, is normal
• within cortical layer V, mutant cell bodies appear shrunken and show a 37% decrease in cross sectional area relative to controls
• at P8, homozygotes display a drastic atrophy of the brain cortical mantel as a result of postnatal malnutrition
• at P8, mutant brains show a 34.3% reduction in total cortical thickness from the white mater to pia

• at P8, malnourished homozygotes exhibit a ~7-fold reduction of serum leptin levels to the background detection range (2-3 ng/ml)
• by P2, homozygotes appear unhealthy, dehydrated and malnourished

• by P2, mutant skin is dry
• by P2, mutant skin forms loose folds around the body
• by P2, mutant skin is pale

Mouse Models of Human Disease
OMIM ID Ref(s)
NOT Huntington Disease; HD 143100 J:76174

Contributing Projects:
Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Tumor Biology (MTB), Gene Ontology (GO), MouseCyc
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last database update
MGI 6.07
The Jackson Laboratory