Phenotypes associated with this allele

• Allele Symbol: Hoxb8^tm1.1Mrc
• Allele Name: targeted mutation 1, Mario R Capecchi
• Allele ID: MGI:2159735
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Hoxb8^tm1.1Mrc/Hoxb8^tm1.1Mrc	involves: 129S1/Sv * 129X1/SvJ	MGI:2673421
hm2	Hoxb8^tm1.1Mrc/Hoxb8^tm1.1Mrc	involves: 129S1/Sv * 129X1/SvJ * C57BL/6 * SJL	MGI:4818890

Genotype
MGI:2673421

hm1

• Allelic Composition: Hoxb8^tm1.1Mrc/Hoxb8^tm1.1Mrc
• Genetic Background: involves: 129S1/Sv * 129X1/SvJ

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

behavior/neurological

increased grooming behavior ( J:73745 )

• spend almost twice as much time grooming compared to controls, initiate grooming more frequently, spend excessive time on body licking and biting which leads to hair loss, and excessively groom cagemates, however forelimb clasping, motor control and rearing are normal

abnormal sleep pattern ( J:73745 )

• spend on average one hour less time sleeping than controls

skeleton

skeleton phenotype ( J:73745 )

N • no defects in the formation of the first rib are detected

nervous system

nervous system phenotype ( J:73745 )

N • no defects either in formation or maintenance of the dorsal root ganglia

integument

abnormal coat appearance ( J:73745 )

• varied hair loss showing large bald patches on lateral and ventral body surfaces due to excessive grooming

abnormal skin condition ( J:73745 )

• self-inflicted skin lesions due to excessive grooming, with thickened epidermis in hairless patches of older mice, however observe no inflammation in the area and no defect in cutaneous sensation

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
trichotillomania		DOID:0050587	OMIM:613229	J:73745

Genotype
MGI:4818890

hm2

• Allelic Composition: Hoxb8^tm1.1Mrc/Hoxb8^tm1.1Mrc
• Genetic Background: involves: 129S1/Sv * 129X1/SvJ * C57BL/6 * SJL

behavior/neurological

abnormal grooming behavior ( J:162102 )

• hair removal in mutants is done with teeth rather than paw scratching; time spent engaged in scratching behavior is similar between controls and most mutants

increased grooming behavior ( J:162102 )

• mutants spend about twice as much time in grooming in a 24 hour period compared to controls

• lidocaine treatment of mutants does not alter overgrooming, indicating that behavior is not result of response to chronic itching

increased thermal nociceptive threshold ( J:162102 )

• mutants have significantly greater latency time in response to heat

• nociceptive defect is not rescued by transplantation of wild-type bone marrow into irradiated mutants

nervous system

abnormal microglial cell morphology ( J:162102 )

• a 15% reduction in the total number of microglia is observed in homozygotes compared to controls

abnormal spinal cord dorsal horn morphology ( J:162102 )

• disorganization and reduction in numbers of input sensory fibers and of interneurons in laminae I and II are detected

• in adult animals, significant decrease in neuronal cell body numbers is detected relative to wild-type controls

immune system

abnormal microglial cell morphology ( J:162102 )

• a 15% reduction in the total number of microglia is observed in homozygotes compared to controls

hematopoietic system

abnormal microglial cell morphology ( J:162102 )

• a 15% reduction in the total number of microglia is observed in homozygotes compared to controls

integument

focal hair loss ( J:162102 )

• hair removal progresses along ventral surface and extends to lateral surfaces with excessive grooming

skin lesions ( J:162102 )

• result from excessive grooming on ventral surface of body and extending to lateral surfaces