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SL Ball, D Bardenstein, K Alagramam; Characterization of retinal function in the Ames Waltzer mouse . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1778.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:The mouse mutation Ames waltzer (av) is a recessive mutation, which causes deafness and vestibular dysfunction associated with degeneration of the inner ear neuroepithelia. The gene that harbors the av mutation was identified as a protocadherin, Pcdh15. A recent report shows that the mutation in the human homologue of the mouse Pcdh15 causes Usher syndrome type 1F, which leads to congenital hearing loss, vestibular areflexia, and retinitis pigmentosa. Four different alleles (four different mutations within the same gene) of av have been identified, and all four mutants show inner ear defects. However, it is not known whether a retinal phenotype is associated with the av mutation. Here we have assessed retinal function and structure in these mice. Methods: We tested affected homozygotes and heterozygous littermate controls for each mutation as well as compound heterozygous mice. Animals 3-4 months and over 12 months of age were anesthetized and electroretinograms (ERG)s were recorded under dark- and light-adapted conditions. The amplitude and latency of the a- and b-waves were measured under each condition in each animal. After recordings were made, animals were given a lethal overdose and eyes were enucleated and postfixed overnight in 8% paraformaldehyde. For anatomical analysis, eyecups were embedded in paraffin and 10 mm sections were mounted and stained with hematoxyl/eosin. Genotypes of all animals were confirmed by PCR analysis. Results:No significant differences in ERG amplitude or timing were found between any av-mutant line and control mice under any conditions recorded. This result was obtained in young and in aged affected mice. No gross anatomical abnormalities were noted in the retinas of the transgenic mice. Conclusion:Although av-mutant mice possess a similar genetic defect and other sensory abnormalities associated with Ushers syndrome, retinal structure and function are normal. A more complete assessment of the visual system may shed some light on this unexplained result.
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