Table 1.

Overview of Clinical, Genetic, and Radiological Features

	P1	P2
Ethnic background	Spanish	Italian
Sex	Male	Male
GNAO1 variant (NM_020988.3)	c.412C>T/p.E138*	c.644G>A/p.C215F
Age at last exam (years)	14	14
Age at sitting (months)	9	6
Age at walking (months)	15	12
Age at first words (years)	1	1
Intellectual disability	ASD, ADHD	Subtle disfluency noted at 4 years of age.
Movement disorders	Mild left foot dystonia	Subtle postural tremor
Seizures (age onset)	Simple febrile seizure at 14 months. Motor generalized onset seizure with fever at 6.5 years of age	Motor and nonmotor generalized onset seizures at 7 years of age
VideoEEG	Normal background activity. Multifocal bilateral epileptiform abnormalities during sleep.	Normal awake and sleep EEG
Treatment	Valproic acid, lisdexamfetamine dimesylate	Valproic acid
Neuroimaging (MRI)	Normal	Normal
GNAO1 Severity Score
Epilepsy	0,25	0,25
Movement Disorders	0,25	0,25
Gross motor development	0	0
Language development	0	0
Feeding	0	0
Total	0,5	0,5

Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD)