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Accurate identification can help improve the care and management of patients with AADC deficiency1,2

Diagnostic pathway for suspected AADC deficiency2,3

How AADC deficiency is diagnosed

Adapted from Himmelreich 2019.2

3-OMD=3-O-methyldopa; 5-HIAA=5-hydroxyindoleacetic acid; 5-HTP=5-hydroxytryptophan; CSF=cerebrospinal fluid; HVA=homovanillic acid; 
L-dopa=L-3,4-dihydroxyphenylalanine; MHPG=3-methoxy-4-hydroxyphenylglycol; VLA=vanillactic acid.

Other tests that may be helpful include4-7:

  • Blood level measurement of 3-OMD
  • Urinary organic acid analysis

Current consensus guidelines recommend performing a CSF neurotransmitter metabolite panel and/or plasma AADC enzyme activity assay in combination with genetic testing to confirm a diagnosis of AADC deficiency.3

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WATCH: Which tests are appropriate for AADC deficiency?

Keith Hyland, PhD, reviews diagnostic tests that can confirm an AADC deficiency diagnosis

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References: 1. Pons R, Ford B, Chiriboga CA, et al. Aromatic L-amino acid decarboxylase deficiency: clinical features, treatment, and prognosis. Neurology. 2004;62(7):1058-1065. 2. Himmelreich N, Montioli R, Bertoldi M, et al. Aromatic amino acid decarboxylase deficiency: molecular and metabolic basis and therapeutic outlook. Mol Genet Metab. 2019;127(1):12-22. doi: 10.1016/j.ymgme.2019.03.009. 3. Wassenberg T, Molero-Luis M, Jeltsch K, et al. Consensus guideline for the diagnosis and treatment of aromatic L-amino acid decarboxylase (AADC) deficiency. Orphanet J Rare Dis. 2017;12(1):12. doi: 10.1186/s13023-016-0522-z. 4. Monteleone B, Hyland K. Case report: discovery of 2 gene variants for aromatic L-amino acid decarboxylase deficiency in 2 African American siblings. BMC Neurol. 2020;20(1):12. doi: 10.1186/s12883-019-1596-8. 5. Chen P-W, Lee N-C, Chien Y-H, et al. Diagnosis of aromatic L-amino acid decarboxylase deficiency by measuring 3-O-methyldopa concentrations in dried blood spots. Clin Chim Acta. 2014;431:19-22. 6. Chien Y-H, Chen P-W, Lee N-C, et al. 3-O-methyldopa levels in newborns: result of newborn screening for aromatic L-amino-acid decarboxylase deficiency. Mol Genet Metab. 2016;118(4):259-263. doi: 10.1016/j.ymgme.2016.05.011. 7. Brennenstuhl H, Kohlmüller D, Gramer G, et al. High throughput newborn screening for aromatic L-amino-acid decarboxylase deficiency by analysis of concentrations of 3-O-methyldopa from dried blood spots. J Inherit Metab Dis. 2020;43(3):602-610. doi: 10.1002/jimd.12208.