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Retinal Dysfunction in a Mouse Model of HCN1 Genetic Epilepsy
Da Zhao1, Paulo Pinares-Garcia2, Chaseley E McKenzie2
1Department of Optometry and Vision Sciences, School of Health Sciences, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne, Parkville 3010, Victoria, Australia.
Summary
Genetic variants in HCN1 channels cause epilepsy and impair vision. A mouse model shows reduced light sensitivity and impaired temporal processing in the retina, suggesting visual dysfunction in patients.
Area of Science:
- Neuroscience
- Genetics
- Ophthalmology
Background:
- Pathogenic variants in HCN1 are linked to epilepsy and developmental disorders.
- HCN1 channels are crucial for neuronal function and are highly expressed in retinal photoreceptors.
Purpose of the Study:
- To investigate the impact of a specific recurrent HCN1 pathogenic variant (M305L) on retinal function.
- To evaluate visual phenotypes in a mouse model (Hcn1M294L) carrying this variant.
Main Methods:
- Electroretinogram (ERG) recordings in Hcn1M294L mice.
- Comparison of ERG responses between mutant and wild-type mice.
- In silico modeling of photoreceptor function with mutated HCN1 channels.
Main Results:
- Hcn1M294L mice exhibited significantly decreased photoreceptor sensitivity to light and attenuated responses in bipolar and retinal ganglion cells.
- ERG recordings showed reduced responses to flickering lights in mutant mice.
- In silico modeling indicated that the mutated HCN1 channel impairs light-induced hyperpolarization and reduces the dynamic range of the photoreceptor response.
Conclusions:
- HCN1 channels are critical for normal retinal function, specifically in light and temporal processing.
- Patients with HCN1 pathogenic variants likely experience reduced light sensitivity and impaired visual temporal processing.
- ERG abnormalities may serve as a biomarker for HCN1-related epilepsy and visual dysfunction.
