The purpose of this protocol is to create a registry for patients diagnosed with Glucose Transporter Type 1 Deficiency (G1D), or patients experiencing symptoms consistent with G1D but not yet diagnosed, to enter medical information for physicians and other health researchers to analyze to increase the understanding of G1D and any sub-diagnoses.

This is a registry for patients diagnosed with G1D, or experiencing symptoms G1D but not yet diagnosed. The registry will be available online for patients to provide consent, register, enter data, and modify data as necessary. The registry will be programmed by programmers at UT Southwestern Medical Center. The registry will provide the opportunity for patients to enter a comprehensive medical history, from symptoms to lab results to medications and other treatment regimens.

This registry is entirely patient-driven; no medical records will be requested by the investigator, nor are visits with the investigator or any other research personnel required.

The registry database will be periodically "cleaned"; that is, records will be reviewed for duplication of entries and consistency of data. Many data validation checks are incorporated into the registry. Additional data clarification may be requested from users if users have chosen to provide an email address for contact.

Inclusion Criteria:

• Males and females
• G1D diagnosis
• Patients experiencing symptoms of G1D but who have not yet received a diagnosis

Exclusion Criteria:

• Patients who are not experiencing any symptoms of G1D

Patients will be recruited from the investigator's patients at the Rare Brain Disorders Clinic and from the national and international community of patients with Glucose Transporter Type I Deficiency