Ultragenyx resubmitted an approval application to the FDA for its AAV gene therapy candidate UX111 targeting Sanfilippo syndrome type A, following a prior rejection. The company refined its submission package in response to regulatory feedback and is seeking to clear the hurdles identified during the first review. The resubmission indicates Ultragenyx believes it has addressed the FDA’s prior concerns on clinical or manufacturing matters; the dossier will be re‑evaluated under applicable review timelines. The program represents an important rare‑disease gene therapy play with meaningful clinical need and high unmet demand. A successful resubmission could reinvigorate investor interest in the program and inform regulatory expectations for AAV therapies in neurodegenerative pediatric indications.