DDC and aromatic L-amino acid decarboxylase deficiency: These include cerliponase alfa enzyme replacement therapy for ceroid lipofuscinosis type 2 (late infantile Batten disease) [8], advances in spinal muscular atrophy treatment with the antisense oligonucleotide treatment nusinersen [9], and targeted gene therapy for aromatic L-amino acid decarboxylase (AADC) deficiency [10, 11].