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Purpose: A local colony of inbred mice (129S6/SvEvTac origin), in isolation for over a decade, were found to have absent light-adapted electroretinogram (ERG) responses. We investigated the inheritance and genetic basis of this phenotype of cone photoreceptor function loss. Methods: An affected 129S6/SvEvTac colony animal was outcrossed to a C57BL/6J mouse and intercrossed to investigate inheritance in the F2 generation. We performed ERG testing and targeted resequencing on genes of interest (Gnat2, Cnga3, Cngb3, Pde6c, Hcn1, Syne2). The eyes of a subset of animals underwent histologic immunostaining. Results: All 129S6/SvEvTac colony animals tested lacked cone pathway function by ERG testing (n = 12), although rod pathway-based ERG responses remained unaffected. Outcross-intercross breeding showed a recessive inheritance pattern. A novel missense mutation was identified in the Cngb3 gene, which causes an amino acid substitution at a conserved residue (NM_013927)c.692G>A; p.(R231H). The recessive phenotype only affected homozygotes (χ2 = 39, P = 3.2e-10). Cones had normal morphology at postnatal day (PND) 70, but cone cell counts declined from PND 30 to PND 335 (P = 0.038), indicating progressive cone photoreceptor death. Conclusions: We identified the spontaneous occurrence of a 10th model of cone photoreceptor function loss (cpfl10) in an isolated line of inbred mice. Our results indicate that this is caused by a novel missense mutation in the Cngb3 gene, with a fully recessive inheritance pattern. This mouse may provide a more appropriate background against which to assess CNGB3 achromatopsia gene therapy for missense mutations.

Original publication

DOI

10.1167/iovs.18-24328

Type

Journal article

Journal

Invest Ophthalmol Vis Sci

Publication Date

03/12/2018

Volume

59

Pages

6102 - 6110

Keywords

Animals, Color Vision Defects, Cyclic Nucleotide-Gated Cation Channels, Dark Adaptation, Disease Models, Animal, Electroretinography, Exons, Female, Genotyping Techniques, Male, Mice, Mice, Inbred C57BL, Mutation, Missense, Ophthalmoscopy, Polymorphism, Restriction Fragment Length, RNA, Messenger, Real-Time Polymerase Chain Reaction, Retina, Retinal Cone Photoreceptor Cells, Tomography, Optical Coherence