Related Experiment Video
Updated: Aug 28, 2025
Author Spotlight: A Battery of Highly Reproducible Behavioral Tests to Validate an Angelman Syndrome Murine Model
Published on: October 20, 2023
Residual rod function in CNGB1 mutant dogs
Simon M Petersen-Jones1, Nathaniel Pasmanter2, Laurence M Occelli2
1Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road, D-208, East Lansing, MI, 48824, USA. peter315@msu.edu.
Purpose:
Mutations in the cyclic nucleotide-gated (CNG) channel beta subunit (CNGB1) are an important cause of recessive retinitis pigmentosa. We identified a large animal model with a truncating mutation of CNGB1. This study reports the persistence of small, desensitized rod ERG responses in this model.
Methods:
Dark-, light-adapted and chromatic ERGs were recorded in CNGB1 mutant dogs and age and breed matched controls. Comparisons were made with a dog model known to completely lack rod function; young dogs with a mutation in the rod phosphodiesterase 6 alpha subunit (PDE6A-/-). Immunohistochemistry (IHC) to label the rod CNG alpha (CNGA1) and CNGB1 subunits was performed.
Results:
The dark-adapted ERG of CNGB1 mutant dogs had a raised response threshold with lack of normal rod response and a remaining cone response. Increasing stimulus strength resulted in the appearance of a separate, slower positive waveform following the dark-adapted cone b-wave. With increasing stimulus strength this increased in amplitude and became faster to merge with the initial b-wave. Comparison of responses from PDE6A-/- (cone only dogs) with CNGB1 mutant dogs to red and blue flashes and between dark-adapted and light-adapted responses supported the hypothesis that the CNGB1 mutant dog had residual desensitized rod responses. CNGB1 mutant dogs had a small amount of CNGA1 detectable in the outer segments.
Conclusions:
CNGB1 mutant dogs have a residual ERG response from desensitized rods. This may be due to low levels of CNGA1 in outer segments.
