Table 3. Comparison of phenotypes among mouse strains segregating different slc26a4 mutations.

	Slc26a4−/−	Slc26a4loop/loop	Slc26a4tm1Dontuh/tm1Dontuh
Audiological phenotypes	Profound hearing loss	Profound hearing loss	Profound hearing loss
	(>100 dB SPL)	(>100 dB SPL)	(>120 dB SPL)
Vestibular phenotypes	Vestibular deficits, including head-tilting, head-bobbing unsteadiness, circling and abnormal reaching response in ∼50% mice.	Variable vestibular deficits, including unsteady gait, circling, absence of reaching response and tilted body. Proportion of mice with vestibular deficits not reported.	46% of mice with head-tilting and circling. Poorer vestibular function in Slc26a4tm1Dontuh/tm1Dontuh mice, esp. in those with circling.
Inner Ear Morphology
Vestibular aqueduct	Enlarged	ND	Enlarged
Scala media	Enlarged	ND	Enlarged
Stria vascularis	Atrophic	ND	Atrophic
Cochlear hair cells	Severe degeneration of inner and outer hair cells by P30.	ND	Severe degeneration of inner and outer hair cells at 6 wks.
Vestibular hair cells	Severe degeneration of vestibular hair cells by P30.	Normal morphology of vestibular hair cells at 2 m.	Loss and degeneration of utricular hair cells correlated to the vestibular phenotypes
Otoconia	Almost complete absence of otoconia with occasional presence of giant otoconia.	Giant otoconia in the utricle from P0 to 10 m; gradual change in otoconia composition to calcium oxalate in the saccule from P0 to 10 m; ectopic otoconia in the semicircular canal.	Decreased amount of otoconia in the saccule and utricle, formation of giant otoconia in the saccule and utricle, and ectopic distribution of otoconia into the semicircular canal

ND, not described.

^* Slc26a4^loop/loop: mice homozygous for the p.S408F mutation.