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

Background: Infants and children with dominant de novo mutations in GNAO1 exhibit 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 mutant GNAO1 allele. Objectives: Here we develop a mouse model carrying a human GNAO1 mutation and determine whether clinical features of the GNAO1 mutation including movement disorder would be evident in the mouse model. Methods: A mouse Gnao1 knock-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. Results: Gnao1 +/G203R mutant mice are viable and gain weight comparably to controls. Homozygotes are non-viable. Grip strength was decreased in both males and females. Male Gnao1 +/G203R mice were strongly affected in movement assays (RotaRod and DigiGait) while females were not. Male Gnao1 +/G203R mice 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. Conclusions: Gnao1 +/G203R mice phenocopy children with heterozygous GNAO1 G203R mutations, showing both movement disorder and a relatively mild epilepsy pattern. This mouse model should be useful in mechanistic and preclinical studies of GNAO1 -related movement disorders.