Phenotypes associated with this allele

• Allele Symbol: Htt^tm2Szi
• Allele Name: targeted mutation 2, Scott Zeitlin
• Allele ID: MGI:2177755
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
cn1	Htt^tm1Szi/Htt^tm2Szi Tg(Camk2a-cre)1Szi/0	involves: 129S/SvEv * 129S1/Sv * C57BL/6 * CBA	MGI:3605769
cn2	Htt^tm1Szi/Htt^tm2Szi Tg(Camk2a-cre)2Szi/0	involves: 129S/SvEv * 129S1/Sv * C57BL/6 * CBA	MGI:3605770

Genotype
MGI:3605769

cn1

• Allelic Composition: Htt^tm1Szi/Htt^tm2Szi; Tg(Camk2a-cre)1Szi/0
• Genetic Background: involves: 129S/SvEv * 129S1/Sv * C57BL/6 * CBA

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

mortality/aging

premature death ( J:65520 )

• die between 11 and 13 months of age

growth/size/body

decreased body size ( J:65520 )

• smaller than controls at weaning and at P60

behavior/neurological

limb grasping ( J:65520 )

• abnormal limb clasping at P60 that becomes progressively more severe such that mice curl their body upon clasping and maintain the posture for several seconds following return to cage

tremors ( J:65520 )

• exhibit a slight tremor at 10-12 months of age

impaired coordination ( J:65520 )

• exhibit motor defects in mutants subjected to cage-top rotation test and elevated wire rod hanging test

decreased locomotor activity ( J:65520 )

• noticeably hypoactive at 10-12 months of age

nervous system

gliosis ( J:65520 )

• gliosis is seen throughout the forebrain in older mutants

astrocytosis ( J:65520 )

• reactive astocytosis in the entorhinal cortex, striatum, and frontal cortex at 4 and 10 months of age

neurodegeneration ( J:65520 )

• 4 and 8 month old mutants exhibit neurodegeneration in the external capsule fibre tracts and in fibre bundles of the internal capsule within the striatum, in the amygdala and in both the frontal and dorsal cortex

reproductive system

oligozoospermia ( J:65520 )

♂ • exhibit a reduction in the number of spermatocytes and round spermatids in the seminiferous tubules and in mature motile sperm in the lumen of the epididymis

abnormal seminiferous tubule morphology ( J:65520 )

♂ • disorganized and contain fewer spermatocytes and round spermatids compared to controls

small testis ( J:65520 )

♂ • testis is about 50% the weight of controls

reduced male fertility ( J:65520 )

♂

endocrine/exocrine glands

abnormal seminiferous tubule morphology ( J:65520 )

♂ • disorganized and contain fewer spermatocytes and round spermatids compared to controls

small testis ( J:65520 )

♂ • testis is about 50% the weight of controls

cellular

oligozoospermia ( J:65520 )

♂ • exhibit a reduction in the number of spermatocytes and round spermatids in the seminiferous tubules and in mature motile sperm in the lumen of the epididymis

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
Huntington's disease		DOID:12858	OMIM:143100	J:65520

Genotype
MGI:3605770

cn2

• Allelic Composition: Htt^tm1Szi/Htt^tm2Szi; Tg(Camk2a-cre)2Szi/0
• Genetic Background: involves: 129S/SvEv * 129S1/Sv * C57BL/6 * CBA

mortality/aging

premature death ( J:65520 )

• mutants that are hydrocephalic die by P35

• none survive longer than 13 months

growth/size/body

decreased body size ( J:65520 )

• smaller than controls at weaning and at P60

behavior/neurological

limb grasping ( J:65520 )

• abnormal limb clasping at P21 that becomes progressively more severe such that mice curl their body upon clasping and maintain the posture for several seconds following return to cage

tremors ( J:65520 )

• exhibit a slight tremor at 10-12 months of age

impaired coordination ( J:65520 )

• exhibit motor defects in mutants subjected to cage-top rotation test and elevated wire rod hanging test

decreased locomotor activity ( J:65520 )

• noticeably hypoactive at 10-12 months of age

nervous system

hydrocephaly ( J:65520 )

• about 8% are hydrocephalic by P10

abnormal brain internal capsule morphology ( J:65520 )

abnormal striatum morphology ( J:65520 )

• striatum is disorganized at 8-months of age

abnormal cerebral cortex morphology ( J:65520 )

• cortex is disorganized at 8-months of age

gliosis ( J:65520 )

• gliosis is seen throughout the forebrain in young mutants

astrocytosis ( J:65520 )

• reactive astocytosis in the entorhinal cortex, striatum, and frontal cortex at 4 and 8 months of age

neurodegeneration ( J:65520 )

• neurodegeneration in the caudal/lateral region of the cortex at 4-6 months of age and in the rostral and caudal portions of the brain adjacent to the external capsule and in the entorhinal cortex at 8 months of age

• exhibit shrunken eosinophilic neurons, indicative of neuronal damage, in the hippocampus at 8-months of age

• 8 month old mutants exhibit neurodegeneration in the external capsule fibre tracts and in fibre bundles of the internal capsule within the striatum, in the amygdala and in both the frontal and dorsal cortex

• degeneration is essentially complete by 10 months

reproductive system

oligozoospermia ( J:65520 )

♂ • exhibit a reduction in the number of spermatocytes and round spermatids in the seminiferous tubules and in mature motile sperm in the lumen of the epididymis

abnormal seminiferous tubule morphology ( J:65520 )

♂ • disorganized and contain fewer spermatocytes and round spermatids compared to controls

small testis ( J:65520 )

♂ • testis is about 50% the weight of controls

reduced male fertility ( J:65520 )

♂

endocrine/exocrine glands

abnormal seminiferous tubule morphology ( J:65520 )

♂ • disorganized and contain fewer spermatocytes and round spermatids compared to controls

small testis ( J:65520 )

♂ • testis is about 50% the weight of controls

cellular

oligozoospermia ( J:65520 )

♂ • exhibit a reduction in the number of spermatocytes and round spermatids in the seminiferous tubules and in mature motile sperm in the lumen of the epididymis

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
Huntington's disease		DOID:12858	OMIM:143100	J:65520