Mouse Genome Informatics
hm
    Foxi1tm1Sven/Foxi1tm1Sven
involves: CD-1
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
       
hearing/vestibular/ear
• at E16.5, the basal turn of the cochlea is larger while the apical turn has formed an apical cyst
• at E16.5, homozygotes show a prominent expansion of the common crus
• at E16.5, homozygotes show a prominent expansion of the lateral semicircular canal
• at E16.5, homozygotes show a prominent expansion of the posterior semicircular canal, common crus and ampullae
• at E16.5, the entire membranous labyrinth appears enlarged; no major aberrations are observed up to E13.5
• at E16.5, the mutant utricle is significantly enlarged relative to wild-type
• at E16.5, the mutant saccule is significantly enlarged relative to wild-type
• at E16.5, homozygotes exhibit a pronounced expansion of the endolymphatic compartment
• by P12, the peri- and endolymphatic compartments of the inner ear have been replaced by a common irregular cavity
• at E16.5, homozygotes exhibit a severe dilatation of the endolymphatic sac
• homozygotes show complete absence of the normally white utricular and saccular otoconia found in wild-type, suggesting defective crystallization of calcium carbonate crystals
• homozygotes display cystic dilatation of the inner ears at E18.5
• homozygotes lack an endocochlear potential indicating a primary defect in fluid homeostasis in the inner ear
• homozygotes are deaf

craniofacial
• the mutant temporal bone is thinner adjacent to the inner ear relative to wild-type
• at E18.5, homozygotes show abnormal integration of the otic capsule into the temporal bone anlagen associated with ectopic cartilage and/or bone formation

cellular
• at E16.5, homozygotes show a minor increase of apoptosis in a small mesenchymal cell population adjacent to the expanded endolymphatic duct

nervous system
• the mutant cerebellum appears compressed due to the severe expansion of the inner ear

renal/urinary system
• homozygotes fail to secrete protons in response to both a chronic as well as an acute acidic load
• homozygotes are unable to acidify the urine and display a reduced systemic buffer capacity
• homozygotes develop renal tubular acidosis in response to a prolonged acidic load
• homozygotes produce urine with elevated pH relative to wild-type
• homozygotes show ultrastructural changes in the epithelium of the cortical collecting duct (CCD)
• mitochondria-rich cells with a protruding "tussock-like" apex are missing from mutants CCDs
• the distal nephron epithelium with its two major cell types (principal and intercalated cells) is replaced by a single cell type positive for both principal and intercalated cell markers

homeostasis/metabolism
• homozygotes fail to secrete protons in response to both a chronic as well as an acute acidic load
• homozygotes are unable to acidify the urine and display a reduced systemic buffer capacity
• homozygotes develop renal tubular acidosis in response to a prolonged acidic load
• homozygotes produce urine with elevated pH relative to wild-type

skeleton
• the mutant temporal bone is thinner adjacent to the inner ear relative to wild-type
• at E18.5, homozygotes show abnormal integration of the otic capsule into the temporal bone anlagen associated with ectopic cartilage and/or bone formation

Mouse Models of Human Disease
OMIM IDRef(s)
Pendred Syndrome; PDS 274600 J:83207