Taysha Gene Therapies, Inc. announced that it has received both rare pediatric disease and orphan drug designations from the U.S. Food and Drug Administration (FDA) for TSHA-105, an AAV9-based gene therapy in development for SLC13A5-related epilepsy. SLC13A5 is a form of infantile epilepsy caused by mutations in the SLC13A5 gene. The disorder is an autosomal recessive disorder, so two copies of the mutated gene must be inherited to affect an infant. This rare form of epilepsy manifests as developmental delay, and seizures beginning within the first few days of life. The FDA grants rare pediatric disease designation for serious and life-threatening diseases that primarily affect children ages 18 years or younger and fewer than 200,000 people in the United States. The Rare Pediatric Disease Priority Review Voucher Program is intended to address the challenges that drug companies face when developing treatments for these unique patient populations. Under this program, companies are eligible to receive a priority review voucher following approval of a product with rare pediatric disease designation if the marketing application submitted for the product satisfies certain conditions, including approval prior to September 30, 2026 unless changed by legislation. If issued, a sponsor may redeem a priority review voucher for priority review of a subsequent marketing application for a different product candidate, or the priority review voucher could be sold or transferred to another sponsor. Orphan drug designation is granted by the FDA Office of Orphan Products Development to investigational treatments that are intended for the treatment of rare diseases affecting fewer than 200,000 people in the United States. The program was developed to encourage the development of medicines for rare diseases, and benefits include tax credits and application fee waivers designed to offset some development costs, as well as eligibility for market exclusivity for seven years post approval.