Project description:ObjectiveTo describe a characteristic paroxysmal eye-head movement disorder that occurs in infants with Glut1 deficiency syndrome (Glut1 DS).MethodsWe retrospectively reviewed the medical charts of 101 patients with Glut1 DS to obtain clinical data about episodic abnormal eye movements and analyzed video recordings of 18 eye movement episodes from 10 patients.ResultsA documented history of paroxysmal abnormal eye movements was found in 32/101 patients (32%), and a detailed description was available in 18 patients, presented here. Episodes started before age 6 months in 15/18 patients (83%), and preceded the onset of seizures in 10/16 patients (63%) who experienced both types of episodes. Eye movement episodes resolved, with or without treatment, by 6 years of age in 7/8 patients with documented long-term course. Episodes were brief (usually <5 minutes). Video analysis revealed that the eye movements were rapid, multidirectional, and often accompanied by a head movement in the same direction. Eye movements were separated by clear intervals of fixation, usually ranging from 200 to 800 ms. The movements were consistent with eye-head gaze saccades. These movements can be distinguished from opsoclonus by the presence of a clear intermovement fixation interval and the association of a same-direction head movement.ConclusionsParoxysmal eye-head movements, for which we suggest the term aberrant gaze saccades, are an early symptom of Glut1 DS in infancy. Recognition of the episodes will facilitate prompt diagnosis of this treatable neurodevelopmental disorder.
Project description:BackgroundA rare symptom of Glut1 deficiency syndrome (Glut1 DS) is hemiplegic migraine (HM).CaseWe report a patient with Glut1 DS with a mild phenotype. His leading symptom was HM. As an unusual complication of the initiation of a ketogenic diet (KD), our patient developed paroxysmal nonkinesigenic dyskinesia. Paroxysmal dyskinesia occurred first and exclusively at the initiation of KD.Literature reviewThere are a few case reports for HM in Glut1 DS. All patients had additional neurological symptoms. Regarding central nervous system symptoms such as paroxysmal dyskinesia triggered by KD, we found only 1 other case report.DiscussionHM is part of the symptom complex of Glut1 DS and can be effectively treated by KD. Paroxysmal dyskinesia trigged by the initiation of KD should not lead to the discontinuation of the diet in Glut1 DS.
Project description:View Supplementary Video Movement disorders are a major feature of Glut1 deficiency. As recently identified in adults with paroxysmal exercise-induced dystonia, similar events were reported in pediatric Glut1 deficiency. In a case series, parent videos of regular motor state and paroxysmal events were requested from children with Glut1 deficiency on clinical follow-up. A questionnaire was sent out to 60 families. Videos of nonparoxysmal/paroxysmal states in 3 children illustrated the ataxic-dystonic, choreatiform, and dyskinetic-dystonic nature of paroxysmal events. Fifty-six evaluated questionnaires confirmed this observation in 73% of patients. Events appeared to increase with age, were triggered by low ketosis, sleep deprivation, and physical exercise, and unrelated to sex, hypoglycorrhachia, SLC2A1 mutations, or type of ketogenic diet. We conclude that paroxysmal events are a major clinical feature in Glut1 deficieny, linking the pediatric disease to adult Glut1D-associated exercise-induced paroxysmal dyskinesias.
Project description:ObjectiveOn the basis of our previous work with triheptanoin, which provides key substrates to the Krebs cycle in the brain, we wished to assess its therapeutic effect in patients with glucose transporter type 1 deficiency syndrome (GLUT1-DS) who objected to or did not tolerate ketogenic diets.MethodsWe performed an open-label pilot study with three phases of 2 months each (baseline, treatment and withdrawal) in eight patients with GLUT1-DS (7-47 years old) with non-epileptic paroxysmal manifestations. We used a comprehensive patient diary to record motor and non-motor paroxysmal events. Functional (31)P-NMR spectroscopy was performed to quantify phosphocreatine (PCr) and inorganic phosphate (Pi) within the occipital cortex during (activation) and after (recovery) a visual stimulus.ResultsPatients with GLUT1-DS experienced a mean of 30.8 (± 27.7) paroxysmal manifestations (52% motor events) at baseline that dropped to 2.8 (± 2.9, 76% motor events) during the treatment phase (p = 0.028). After withdrawal, paroxysmal manifestations recurred with a mean of 24.2 (± 21.9, 52% motor events; p = 0.043). Furthermore, brain energy metabolism normalised with triheptanoin, that is, increased Pi/PCr ratio during brain activation compared to the recovery phase (p = 0.021), and deteriorated when triheptanoin was withdrawn.ConclusionsTreatment with triheptanoin resulted in a 90% clinical improvement in non-epileptic paroxysmal manifestations and a normalised brain bioenergetics profile in patients with GLUT1-DS.Trial registration numberNCT02014883.
Project description:Paroxysmal exercise-induced dyskinesia (PED) can occur in isolation or in association with epilepsy, but the genetic causes and pathophysiological mechanisms are still poorly understood. We performed a clinical evaluation and genetic analysis in a five-generation family with co-occurrence of PED and epilepsy (n = 39), suggesting that this combination represents a clinical entity. Based on a whole genome linkage analysis we screened SLC2A1, encoding the glucose transporter of the blood-brain-barrier, GLUT1 and identified heterozygous missense and frameshift mutations segregating in this and three other nuclear families with a similar phenotype. PED was characterized by choreoathetosis, dystonia or both, affecting mainly the legs. Predominant epileptic seizure types were primary generalized. A median CSF/blood glucose ratio of 0.52 (normal >0.60) in the patients and a reduced glucose uptake by mutated transporters compared with the wild-type as determined in Xenopus oocytes confirmed a pathogenic role of these mutations. Functional imaging studies implicated alterations in glucose metabolism in the corticostriate pathways in the pathophysiology of PED and in the frontal lobe cortex in the pathophysiology of epileptic seizures. Three patients were successfully treated with a ketogenic diet. In conclusion, co-occurring PED and epilepsy can be due to autosomal dominant heterozygous SLC2A1 mutations, expanding the phenotypic spectrum associated with GLUT1 deficiency and providing a potential new treatment option for this clinical syndrome.
Project description:Mutations in the proline-rich transmembrane protein 2 (PRRT2) are associated with paroxysmal kinesigenic dyskinesia (PKD) and several other paroxysmal neurological diseases, but the PRRT2 function and pathogenic mechanisms remain largely obscure. Here we show that PRRT2 is a presynaptic protein that interacts with components of the SNARE complex and downregulates its formation. Loss-of-function mutant mice showed PKD-like phenotypes triggered by generalized seizures, hyperthermia, or optogenetic stimulation of the cerebellum. Mutant mice with specific PRRT2 deletion in cerebellar granule cells (GCs) recapitulate the behavioral phenotypes seen in Prrt2-null mice. Furthermore, recording made in cerebellar slices showed that optogenetic stimulation of GCs results in transient elevation followed by suppression of Purkinje cell firing. The anticonvulsant drug carbamazepine used in PKD treatment also relieved PKD-like behaviors in mutant mice. Together, our findings identify PRRT2 as a novel regulator of the SNARE complex and provide a circuit mechanism underlying the PRRT2-related behaviors.
Project description:Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a neurometabolic disorder with a complex phenotypic spectrum but simple biomarkers in cerebrospinal fluid. The disorder is caused by impaired glucose transport into the brain resulting from variants in SCL2A1. In 10% of GLUT1DS patients, a genetic diagnosis can not be made. Using whole-genome sequencing, we identified a de novo 5'-UTR variant in SLC2A1, generating a novel translation initiation codon, severely compromising SLC2A1 function. This finding expands our understanding of the disease mechanisms underlying GLUT1DS and encourages further in-depth analysis of SLC2A1 non-coding regions in patients without variants in the coding region.
Project description:CoQ10 deficiency has been recently described in tissues of a patient with GLUT1 deficiency syndrome. Here, we investigated patients and mice with GLUT1 deficiency in order to determine whether low CoQ is a recurrent biochemical feature of this disorder, to justify CoQ10 supplementation as therapeutic option.CoQ10 levels were investigated in plasma, white blood cells, and skin fibroblasts of 16 patients and healthy controls and in the brain, cerebellum, liver, kidney, muscle, and plasma of 4-month-old GLUT1 mutant and control mice.CoQ10 levels in plasma did not show any difference compared with controls. Since most of the patients studied were on a ketogenic diet, which can alter CoQ10 content in plasma, we also analyzed white blood cells and cultured skin fibroblasts. Again, we found no differences. In mice, we found slightly reduced CoQ in the cerebellum, likely an epiphenomenon, and activity of the mitochondrial respiratory chain enzymes was normal.Our data from GLUT1 deficiency patients and from GLUT1 model mice fail to support CoQ10 deficiency as a common finding in GLUT1 deficiency, suggesting that CoQ deficiency is not a direct biochemical consequence of defective glucose transport caused by molecular defects in the SLC2A1 gene.