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GNAO1 encephalopathy: Broadening the phenotype and evaluating treatment and outcome
Federica Rachele Danti1, Serena Galosi1, Marta Romani1
1Department of Paediatrics, Child Neurology and Psychiatry (F.R.D., S.G., V.L.), Sapienza University of Rome, Italy; Molecular Neurosciences, Developmental Neurosciences Programme (F.R.D., J.N., A.M., M.A.K.), University College London Institute of Child Health, UK; Department of Neurology (F.R.D., J.N., A.M., M.A.K.), Great Ormond Street Hospital for Children, London, UK; GENOMA Group (M.R.), Molecular Genetics Laboratory, Rome, Italy; Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories (M.M., E.P., C.B., R.G.), Neuroscience Department, A Meyer Children's Hospital, University of Florence, Italy; Department of Haematology (K.J.C.), University of Cambridge, NHS Blood and Transplant Centre, UK; NIHR Bioresource Rare Diseases (K.J.C., F.L.R.), University of Cambridge, UK; Department of Neurology (N.M.), Westmead Hospital, Sydney, Australia; Childrens Hospital Oxford (T.M.), John Radcliffe Hospital, UK; Institute for Neuroscience and Muscle Research (R.C.D., S.S.M., U.S.), the Children's Hospital at Westmead, University of Sydney, Australia; Department of Medical Genetics (F.L.R.), Cambridge Institute for Medical Research, University of Cambridge, UK; Department of Neurology (R.S.), University Hospitals Leicester NHS Trust, UK; Department of Paediatric Neurology (G.V.), Leeds Teaching Hospitals NHS Trust, UK; Section of Neurosciences (E.M.V.), Department of Medicine and Surgery, University of Salerno, Italy; and Neurogenetics Unit (E.M.V.), IRCCS Fondazione Santa Lucia, Rome, Italy.
Objective:
To describe better the motor phenotype, molecular genetic features, and clinical course of GNAO1-related disease.
Methods:
We reviewed clinical information, video recordings, and neuroimaging of a newly identified cohort of 7 patients with de novo missense and splice site GNAO1 mutations, detected by next-generation sequencing techniques.
Results:
Patients first presented in early childhood (median age of presentation 10 months, range 0-48 months), with a wide range of clinical symptoms ranging from severe motor and cognitive impairment with marked choreoathetosis, self-injurious behavior, and epileptic encephalopathy to a milder phenotype, featuring moderate developmental delay associated with complex stereotypies, mainly facial dyskinesia and mild epilepsy. Hyperkinetic movements were often exacerbated by specific triggers, such as voluntary movement, intercurrent illnesses, emotion, and high ambient temperature, leading to hospital admissions. Most patients were resistant to drug intervention, although tetrabenazine was effective in partially controlling dyskinesia for 2/7 patients. Emergency deep brain stimulation (DBS) was life saving in 1 patient, resulting in immediate clinical benefit with complete cessation of violent hyperkinetic movements. Five patients had well-controlled epilepsy and 1 had drug-resistant seizures. Structural brain abnormalities, including mild cerebral atrophy and corpus callosum dysgenesis, were evident in 5 patients. One patient had a diffuse astrocytoma (WHO grade II), surgically removed at age 16.
Conclusions:
Our findings support the causative role of GNAO1 mutations in an expanded spectrum of early-onset epilepsy and movement disorders, frequently exacerbated by specific triggers and at times associated with self-injurious behavior. Tetrabenazine and DBS were the most useful treatments for dyskinesia.