Aromatic l-amino acid decarboxylase (AADC) deficiency is a rare neurometabolic disorder with heterogeneous phenotypic spectrum resulting from disease-causing variants of the dihydroxyphenylalanine (l-DOPA) decarboxylase (DDC) gene [1–4]. The gene discussed is DDC; the disease is hyperinsulinemic hypoglycemia, familial, 4.