A novel frameshift variant in the gene causing a mild phenotype of GLUT1 deficiency syndrome: case report.

Glucose transporter type 1 deficiency syndrome (GLUT1) is a genetic condition, most often of autosomal dominant inheritance, and corresponds to a broad spectrum of signs and symptoms due to hypoglycorrhachia, which include seizures, delay in neuropsychomotor development, intellectual disability, movement disorders, dysarthria and postnatal microcephaly. The severity of symptoms are variable. Symptomatic treatment consists of the ketogenic diet, which allows energy supply to the brain through sustained and continuous ketosis. In this study, we report a novel heterozygous frameshift variant (c.855_856insTT; p.Gly286Leufs*55) in the gene in a preschool Brazilian child with atypical phenotype of GLUT1 deficiency syndrome, characterized by ataxia and mild speech delay. Our study enriches the gene mutation spectrum and emphasizes the importance of molecular genetic studies for screening patients with neuropsychomotor developmental delay. : The study enriches the gene mutation spectrum and emphasizes the importance of molecular genetic studies for screening patients with neuropsychomotor developmental delay.