Diagnostic Test Directory

Molecular Genetics Laboratory

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Glucose Transporter type 1 Deficiency Syndrome (SLC2A1)Sequence Analysis

  • Synonyms: GLUT1, GLUT1-DS


    Collect whole blood in a purple top (EDTA) tube (preferred). Extracted DNA is also acceptable.

    Volume Required

    5 ml whole blood or 3 ug extracted DNA

    Minimum Required

    3 ml


    Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday within 24 hours of collection.


    Whole blood can be refrigerated until shipment.

    Unacceptable conditions

    Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.

    Specimen Handling

    Do not heat, freeze or centrifuge blood before shipment. Refrigerate sample until shipment.

Days Performed

Mon - Fri 9:00am to 4:00pm


4 - 5 weeks



Disease Information

Clinical Features:

Glucose transporter type 1 deficiency syndrome (Glut1-DS) is an autosomal dominant disorder characterized by reduced transport of glucose in to the brain. Affected patients present with infantile-onset epileptic encephalopathy associated with delayed neurologic development, acquired microcephaly, ataxia, dystonia and spasticity. Patients with atypical phenotypes present with developmental delay and movement disorders without epilepsy. The diagnosis of Glut1-DS is established with a reduced cerebrospinal fluid (CSF) glucose concentration (hypoglycorrhachia) in the absence of hypoglycemia and low ratio of CSF glucose concentration to blood glucose concentration.

Molecular Genetics:

SLC2A1 (solute carrier family 2, facilitated glucose transporter member 1) is the only gene currently known to be associated with Glut1-DS. Sequence analysis of the SLC2A1 gene will detect mutations in approximately 90% of affected individuals. Whole gene deletions have been reported in 10% of patients. Mutations are most often de novo although a few affected parents have been identified. Parents can be mildly affected.

Test Methods:

We offer DNA sequence analysis of the entire coding region including splice junctions. PCR amplification and sequencing is performed on the coding region. The patient’s gene sequence is then compared to a reference sequence. Sequence variants are classified as mutations, variants of unknown significance or benign variants unrelated to disease. Variants of unknown significance may warrant further studies in the patient and other family members. Large deletions, mutations in promoters, deep intronic regions and other regulatory regions will not be identified with this assay.

Detection Rate:

Sequence analysis of the SLC2A1 gene will detect mutations in 90% of affected individuals. The analytical sensitivity of this assay is 99%.

Related Tests:

Known mutation analysis is available to family members for mutations previously identified by sequence analysis. Prenatal testing is available for families in whom a mutation has been previously identified. Please contact the laboratory director to discuss appropriate testing prior to collecting a prenatal specimen.


Test results with interpretation will be mailed and/or faxed to the referring physician or laboratory following completion of the test. Additional reports will be provided as requested.


The clinical utility of such testing is to support a clinical diagnosis of the disease, facilitate genetic counseling, assess the risk to other first degree relatives and to facilitate testing of at - risk family members.

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