DDC and hyperinsulinemic hypoglycemia, familial, 4: Since AADC deficiency is associated with alterations in the CSF and plasma monoamine profiles (low levels of HVA and DOPAC, accompanied by an increase in 3‐OMD) [21], we found that l‐dopa supplementation in DDC‐KO cells recapitulated the key alterations of monoamine metabolism of AADC deficiency, with a significant increase of 3‐OMD and absent production of dopamine downstream metabolites [2, 3].