Leigh Syndrome Awareness Day is observed worldwide every September 17 to highlight Leigh syndrome, a rare neurometabolic disorder that impacts the central nervous system. Established in 2024 by the Cure Mito Foundation, the day aims to inform the public about the disease, which is characterized by severe neurodegeneration and typically manifests in early childhood. Named after British neuropsychiatrist Archibald Denis Leigh, who described the condition in 1951, Leigh syndrome arises from mutations in mitochondrial or nuclear DNA, affecting energy production in cells. Symptoms can include poor feeding, developmental delays, and various neurological issues, with a prognosis that is often poor. The disease is particularly prevalent in the Saguenay—Lac-Saint-Jean region of Quebec due to genetic factors. There is currently no cure, and treatment focuses on managing symptoms and improving quality of life.