DDC and Nijmegen breakage syndrome: By targeting the ubiquitous expression of aromatic l-amino acid decarboxylase (encoded by the DDC gene) in NB [20], which catalyzes l-DOPA to l-dopamine in the catecholamine biosynthesis pathway, the whole-body metabolic burden of FDOPA also confer a prognostic role in relapsed/refractory NBs [21].