Compatibility of C7 with the Ketogenic Diet in Patients Diagnosed with Glucose Transporter Type 1 Deficiency G1D

5.1.1. Triheptanoin: a triglyceride oil containing three odd-carbon chain-length fatty acids (i.e., a triglyceride of 7-carbon heptanoic acid). Triheptanoin will be taken 4 times (approximately every 6 hours) by mouth for one day. it is dosed 4 times per day, added to ketogenic diet meals (replacing some of the fat in each meal). Subjects will receive supplementation at 45% of daily caloric intake. The oil should be taken with meals, and will be mixed with the rest of the ketogenic diet nutrients for administration. 5.1.2. Fifteen subjects will be enrolled in a 4 day proof of principle trial of triheptanoin. administration of triheptanoin will be done in the Children's Medical Center Dallas epilepsy Monitoring unit. 5.1.3. Subjects will not be required to stop other medications. Subjects will be directed to maintain their usual medications, including rescue seizure medications, as necessary for the course of the study. Subjects may have any clinical medical records transferred back to their referring physician at completion of the study. Primary outcome: C7 metabolism will not interfere with previously acquired ketosis in G1D as measured by no change in eeGi from pre-C7 baseline. Subjects receiving C7 supplementation will experience no interference with ketosis as measured by no change in eeGi.