Fast Five Quiz: Aromatic L-Amino Acid Decarboxylase Deficiency Diagnosis and Management

Stephen L. Nelson, Jr, MD, PhD


September 18, 2020

Figure 1. Genetic mutation, conceptual image.

At least two of the following three core diagnostic test results should be positive to confirm a diagnosis of AADC deficiency:

  • Low CSF levels of 5-HIAA, HVA, and MHPG; increased CSF levels of 3-OMD, L-dopa, and 5-HTP; and normal levels of CSF pterins

  • Compound heterozygous or homozygous pathogenic variants in the DDC gene

  • Decreased AADC enzyme activity in plasma

If the first step performed is genetic testing, functional confirmation should be completed by measuring plasma AADC enzyme activity and/or the neurotransmitter metabolites in CSF. When resources allow, all three of these key diagnostic tests are recommended.

Learn more about the diagnosis of AADC deficiency.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: