Phenotypes associated with this allele

• Allele Symbol: Napa^hyh
• Allele Name: hydrocephaly with hop gait
• Allele ID: MGI:1856610
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Napa^hyh/Napa^hyh	either: C57BL/10J or (C57BL/6J x C3HeB/FeJ-a/a)F1	MGI:3033683
cx2	Napa^hyh/Napa^hyh Napb^tm1Bros/Napb^tm1Bros	involves: C57BL/10J	MGI:4880007

Genotype
MGI:3033683

hm1

• Allelic Composition: Napa^hyh/Napa^hyh
• Genetic Background: either: C57BL/10J or (C57BL/6J x C3HeB/FeJ-a/a)F1

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

mortality/aging

premature death ( J:14015 )

• lethal within 2 months of age on C57BL/10J background

• Background Sensitivity: survival better in (C57BL/6J X C3HeB/FeJ-a/a)F1 and occasionally breed

behavior/neurological

abnormal motor coordination/balance ( J:12732 )

impaired righting response ( J:12732 )

impaired balance ( J:12732 )

abnormal gait ( J:14015 )

• hop gait in all homozygotes

circling ( J:12732 )

• run in circles

craniofacial

domed cranium ( J:12732 )

• domed head becomes apparent in second week of life

hearing/vestibular/ear

hearing/vestibular/ear phenotype ( J:12732 )

N • hearing is normal

skeleton

domed cranium ( J:12732 )

• domed head becomes apparent in second week of life

nervous system

abnormal brain ventricular system morphology ( J:12732 )

hydrocephaly ( J:86347 )

• moderate hydrocephaly at birth

• severe hydrocephaly develops after the closure of the caudal region of the cerebral aqueduct

abnormal brain ependyma morphology ( J:74193 )

• ependymal detachment starts at E12 in the 4th ventricle floor

• at E14 ependymal detachment seen in the floor of the cerebral aqueduct and ventrolateral walls of third ventricle

• at E15 ependymal detachment starts in lateral ventricles and central canal of spinal cord

abnormal cerebral aqueduct morphology ( J:86347 )

• rostral region is stenotic at birth

• mid segment becomes dilated in first week of life

• caudal region becomes obliterated during the first 2 weeks of life

abnormal midbrain morphology ( J:86347 )

abnormal forebrain morphology ( J:12732 )

abnormal cortical marginal zone morphology ( J:88495 )

• heterotopic neurons are found in the marginal zone

abnormal cortical ventricular zone morphology ( J:88495 )

• at E14.5, heterotopic neurons are found in the ventricular zone

dilated lateral ventricle ( J:12732 )

• at birth

• becomes worse with age

abnormal third ventricle morphology ( J:88495 )

• by E14.5 the third ventricle is displaced dorsally

dilated third ventricle ( J:12732 )

• develops with age and worsens over time

abnormal corpus callosum morphology ( J:12732 )

• corpus callosum fails to cross the midline

abnormal cerebral cortex morphology ( J:88495 )

• by E12.5 the floor plate of the mutant forebrain is noticeably wider

• on E14.5, E16.5, and P0 the cerebral cortex is smaller in homozygotes

abnormal hindbrain morphology ( J:12732 )

abnormal cerebellum vermis morphology ( J:12732 )

• distorted rostral vermis of cerebellum

abnormal spinal cord ependymal layer morphology ( J:74193 )

• at E15 ependymal detachment starts in lateral ventricles and central canal of spinal cord

abnormal neuron specification ( J:88495 )

• homozygotes have an excess of early-born neurons and few late-born neurons in the cerebral cortex

• this is the result of precocious generation of neurons and premature depletion of progenitor cells

• apical vesicle localization is severely abnormal in mutants

abnormal spinal cord central canal morphology ( J:48903 )

• the canal of the spinal cord is closed

Genotype
MGI:4880007

cx2

• Allelic Composition: Napa^hyh/Napa^hyh; Napb^tm1Bros/Napb^tm1Bros
• Genetic Background: involves: C57BL/10J

mortality/aging

neonatal lethality ( J:167753 )

nervous system

abnormal synaptic vesicle number ( J:167753 )

• the pool of readily releasable vesicles is smaller than in control neurons

• stimulated total release and extrapolated pool of readily releasable vesicles is smaller than in control neurons

abnormal neuron physiology ( J:167753 )

• the slow release phase of synaptic vesicles is reduced compared to in wild-type neurons

• total charge transfer induced by calcimycin application is less than in similarly treated control neurons

abnormal excitatory postsynaptic currents ( J:167753 )

• following an action potential train, excitatory postsynaptic current depression is faster and stronger than in control neurons