DDC and hyperinsulinemic hypoglycemia, familial, 4: This phenomenon of approvals in rare conditions with no expected spontaneous improvement and limited standard of care options is exemplified in the EMA approval for the drug Upstaza, indicated for the treatment of patients aged 18 months and older with a clinical, molecular, and genetically confirmed diagnosis of aromatic L amino acid decarboxylase (AADC) deficiency with a severe phenotype (Box 1).