In England, UK, NICE (National Institute for Health and Care Excellence) has recommended the use of ZolgensmaTM (onasemnogene abeparvovec) in children < 6–12 months of age with SMA [133], LibmeldyTM (atidarsagene autotemcel) for children with late infantile or early juvenile type MLD [134] and Upstaza (eladocagene exuparvovec) in individuals aged ≥18 months for the treatment of aromatic L-amino acid decarboxylase (AADC) deficiency [135]. This evidence concerns the gene DDC and metachromatic leukodystrophy.