Ultragenyx Pharmaceuticals resubmitted an application to the FDA seeking approval for UX111, an AAV‑based gene therapy for Sanfilippo syndrome type A, following an earlier rejection last summer. The resubmission includes additional data and analyses intended to address the agency’s prior concerns. If approved, UX111 would represent one of the few systemic AAV approvals for severe pediatric neurodegenerative disease and could reshape treatment paradigms for Sanfilippo A. The FDA’s review clock will determine timing for potential approval or additional information requests.