Overview
There are several mouse models of AHC, primarily based on mutations in the ATP1A3 gene, which is causative for the disorder. The main comparative points among these models are the specific ATP1A3 variants they carry, their phenotypic manifestations, and their utility for research.
Mouse Models by ATP1A3 Variant:
- Atp1a3^D801N (called “Mashlool” model): This knock-in model replicates key features of AHC, including paroxysmal hemiplegia, dystonia, and seizures. It has been used to study disease progression and shows mild worsening of some disability scores with age. Behavioral tests at different life stages have been performed.
- Atp1a3^E815K: Another recurrent variant modeled in mice that shows core AHC features similar to D801N, supporting disease mechanism studies.
- Atp1a3^G947R (novel model): This newly generated mouse carries the third most recurrent AHC mutation. It shows several phenotypes including smaller body size, premature lethality, hyperactivity, anxiety-like behaviors, severe motor dysfunctions, cooling-induced hemiplegia and dystonia, and a prominent seizure phenotype with lower thresholds to induced seizures and abnormal EEG activity. This model is useful for studying epilepsy comorbidity and testing therapeutic strategies.
Genetic Background and Survival:
- The novel G947R model bred on a pure C57BL/6J background had reduced viability but was improved by outcrossing to C3HeB/FeJ strain.
- The newer models at Jackson Laboratory use a hybrid B6C3H background, which reduces early death and fragility compared to earlier models.
Phenotypic Comparisons:
- All models recapitulate motor dysfunction, episodic hemiplegia, and dystonia.
- Behavioral abnormalities such as hyperactivity and anxiety-like traits are noted in the G947R model.
- Cooling or stress can trigger hemiplegic or dystonic episodes across models.
- Premature death is seen variably, higher in some backgrounds.
These models collectively offer critical insights into AHC pathophysiology and potential interventions.