Phenotypes Associated with This Genotype

Genotype
MGI:5700050

• Allelic Composition: Pou3f4^sdl/Pou3f4^sdl
• Genetic Background: C3HeB/FeJ-Pou3f4^sdl

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

behavior/neurological

absent startle reflex ( J:220419 )

• at P30, homozygotes fail to exhibit a startle response in a click-box test, unlike wild-type controls

impaired swimming ( J:220419 )

head tossing ( J:220419 )

circling ( J:220419 )

• homozygotes show occasional circling behavior

hearing/vestibular/ear

hearing/vestibular/ear phenotype ( J:220419 )

N • homozygotes display structurally normal middle ear bones

cochlear outer hair cell degeneration ( J:220419 )

• SEM at ages P15-P90 revealed loss of outer hair cells (OHCs), evident from P30 onwards

• by P45, most OHCs have degenerated in the base and middle cochlear regions

• the innermost row of OHCs, closest to the inner hair cells (IHCs), appears to be affected first and most severely

• in contrast, IHCs remain morphologically normal through P90

abnormal stria vascularis morphology ( J:220419 )

• H&E staining revealed that the stria vascularis is detached from the spiral ligament

decreased cochlea coiling ( J:220419 )

• at P0, paint-filled inner ears display shortening of the mutant cochlear duct by almost one turn, similar to a Mondini malformation of the bony labyrinth

increased or absent threshold for auditory brainstem response ( J:220419 )

• homozygotes have an auditory threshold at a broadband sound stimulus above 90dB, whereas wild-type mice have a threshold of 30dB (+/-5dB)

deafness ( J:220419 )

• homozygotes are deaf at P30

abnormal vestibular system physiology ( J:220419 )

• homozygotes show severe vestibular dysfunction in a battery of vestibular tests, including contact righting, tail hang test, observation of circling behavior and swim test

homeostasis/metabolism

increased circulating potassium level ( J:220419 )

• high plasma potassium values (equal to or higher than 5.6 mmol/l) are, in most cases, associated with hearing impairment, head-tossing and occasional circling behavior

nervous system

cochlear outer hair cell degeneration ( J:220419 )

• SEM at ages P15-P90 revealed loss of outer hair cells (OHCs), evident from P30 onwards

• by P45, most OHCs have degenerated in the base and middle cochlear regions

• the innermost row of OHCs, closest to the inner hair cells (IHCs), appears to be affected first and most severely

• in contrast, IHCs remain morphologically normal through P90