GLUT1, or glucose transporter type 1, is a protein that facilitates the transport of glucose across cell membranes. It is primarily found in the brain, red blood cells, and the blood-brain barrier, where it plays a crucial role in providing energy to cells by allowing glucose to enter. Mutations in the GLUT1 gene can lead to GLUT1 deficiency syndrome, a rare genetic disorder that affects brain function. Symptoms may include seizures, developmental delays, and movement disorders. Treatment often involves a ketogenic diet to help manage symptoms and provide alternative energy sources for the brain.