Mouse Models ofGNAO1-Associated Movement Disorder: Allele- and sex-specific differences in phenotypes

AbstractBackgroundInfants and children with dominantde novomutations inGNAO1exhibit movement disorders, epilepsy, or both. Children with loss-of-function (LOF) mutations exhibit Epileptiform Encephalopathy 17 (EIEE17). Gain-of-function (GOF) mutations or those with normal function are found in patients with Neurodevelopmental Disorder with Involuntary Movements (NEDIM). There is no animal model with a human mutantGNAO1allele.ObjectivesHere we develop a mouse model carrying a humanGNAO1mutation and determine whether clinical features of theGNAO1mutation including movement disorder would be evident in the mouse model.MethodsA mouseGnao1knock-in GOF mutation (G203R) was created by CRISPR/Cas9 methods. The resulting offspring and littermate controls were subjected to a battery of behavioral tests. A previously reported GOF mutant mouse knock-in (Gnao1+/G184S) was also studied for comparison.ResultsGnao1+/G203Rmutant mice are viable and gain weight comparably to controls. Homozygotes are non-viable. Grip strength was decreased in both males and females. MaleGnao1+/G203Rmice were strongly affected in movement assays (RotaRod and DigiGait) while females were not. MaleGnao1+/G203Rmice also showed enhanced seizure propensity in the pentylenetetrazole kindling test. Mice with a G184S GOF knock-in also showed movement-related behavioral phenotypes but females were more strongly affected than males.ConclusionsGnao1+/G203Rmice phenocopy children with heterozygousGNAO1G203R mutations, showing both movement disorder and a relatively mild epilepsy pattern. This mouse model should be useful in mechanistic and preclinical studies ofGNAO1-related movement disorders.