INTRODUCTION The GNAO1 gene encodes the α subunit of G protein-coupled receptors. Its mutation causes a variable spectrum that includes early-onset epileptic encephalopathy, neurodevelopmental delay, and movement disorder. Genetic functional studies suggest that gain of function is related to a movement disorder phenotype and loss of function is more related to the epileptic phenotype.

OBJECTIVES To describe 5 pediatric patients with GNAO1 mutations.

MATERIALS AND METHODS Phenotype 1: 4 patients, 2 girls and 2 boys, between 16 months and 12 years, who start early with hypotonia and evolve with global developmental delay, without language development but with very good interaction. They added a progressive orolingual dyskinesia and choreic movements. MRI, neurometabolic studies and neurotransmitters were normal. Two received pharmacological treatment while the other two required DBS for refractory choreic status between 6 and 8 years of age. All 4 have molecular confirmation of a pathogenic mutation in the GNA01 gene. Phenotype 2: A 2 years old boy, with neonatal-onset epileptic encephalopathy. He evolved with global developmental delay, subtle choreic movements and orolingual dyskinesia. Brain MRI and metabolic laboratories were normal. Mutation of the GNAO1 gene is confirmed. He is on plan to start ketogenic therapy.

CONCLUSIONS There are two clinical phenotypes with numerous overlaps. In the Epileptic Encephalopathy phenotype there are few guiding elements that allow us to suspect this mutation over other etiologies. But the Abnormal Movements phenotype is very characteristic, allowing early suspicion and timely intervention with DBS.

Micaela Chinigioli
Raúl Carrea Institute for Neurological Research-FLENI
Argentina

Rocio Alamo
Raúl Carrea Institute for Neurological Research-FLENI
Argentina

Maria Florencia Bracco
Raúl Carrea Institute for Neurological Research-FLENI
Argentina

Mercedes Villanueva
Rául Carrea Institute for Neurological Research- FLENI-
Argentina

Angeles Schteinschnaider
Rául Carrea Institute for Neurological Research- FLENI-
Argentina