From splitting GLUT1 deficiency syndromes to overlapping phenotypes.

Introduction: Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a rare genetic disorder due to mutations or deletions in SLC2A1, resulting in impaired glucose uptake through the blood brain barrier. The classic phenotype includes pharmacoresistant epilepsy, intellectual deficiency, microcephaly and complex movement disorders, with hypoglycorrhachia, but milder phenotypes have been described (carbohydrate-responsive phenotype, dystonia and ataxia without epilepsy, paroxysmal exertion-induced dystonia). The aim of our study was to provide a comprehensive overview of GLUT1DS in a French cohort.

No Mutation in the SLC2A3 Gene in Cohorts of GLUT1 Deficiency Syndrome-Like Patients Negative for SLC2A1 and in Patients with AHC Negative for ATP1A3.

The facilitative glucose transporter-1 (GLUT1) deficiency or de Vivo syndrome is a rare neuropediatric disorder characterized by drug-resistant epilepsy, acquired microcephaly, delayed psychomotor development, intermittent ataxia, and other paroxysmal neurological disorders due to the presence of dominant mutations in the SLC2A1 gene. Alternating hemiplegia of childhood (AHC) is another rare neuropediatric disorder characterized by episodes of hemiplegia developing during the first 1.5 years of life.

Expanding the Spectrum of PMM2-CDG Phenotype.

Congenital Disorders of Glycosylation (CDG) are a group of recently described inborn errors of metabolism affecting glycosylation. CDG are disorders that have been reported with a great variability in the clinical presentation, especially for the most common PMM2-CDG. The classical form is neurologic but severe forms with multisystem disorders and hydrops fetalis have been described.

Intragenic rearrangements in LARGE and POMGNT1 genes in severe dystroglycanopathies.

Dystroglycanopathies are a heterogeneous group of muscular dystrophies with autosomal recessive inheritance characterized by abnormal glycosylation of alpha-dystroglycan. The most severe phenotypes are Walker-Warburg Syndrome (WWS) and muscle-eye-brain disease (MEB) presenting with lissencephaly type II (LIS II) and in which muscular dystrophy is associated with mental retardation and eye abnormalities. To date, six distinct genes, POMT1, POMT2, POMGNT1, FKTN, FKRP, LARGE and recently in one case DPM3, have been shown to be involved in dystroglycanopathies.

Absence of mutation in the SLC2A1 gene in a cohort of patients with alternating hemiplegia of childhood (AHC).

Alternating hemiplegia of childhood (AHC) is a rare neuropediatric disorder classically characterized by episodes of hemiplegia developing in the first months of life, various non-epileptic paroxysmal events and global neurological impairment. If the etiology is unresolved, the disorder is highly suspected to be monogenic with DE NOVO autosomal dominant mutations. A missense mutation in the SLC2A1 gene encoding the facilitative glucose transporter-1 (GLUT1) was recently described in a child fulfilling the existing criteria for the diagnosis of AHC, with the exception of age at onset, thus suggesting a clinical overlap between AHC and GLUT1 deficiency syndrome due to SLC2A1 mutations.