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Recognizing AADC deficiency in your patients
Learn how to detect and confirm this rare genetic disorder

Aromatic L-amino Acid Decarboxylase (AADC) deficiency is an autosomal recessive disorder associated with defects in neurotransmitter synthesis, resulting in profound motor and autonomic dysfunction and developmental delay.1-3

Many symptoms of AADC deficiency are similar to the symptoms of other more common conditions, making diagnosis a challenge.1-4

Key differentiating signs and symptoms

One or a combination of red-flag diagnostic clues should prompt investigation for AADC deficiency.

A 2010 study (n=78) recorded the prevalence of these common symptoms, which can help to identify AADC deficiency.1

Oculogyric crisis1
  • Occurred in 86% of patients (n=67/78)1
  • Episodes of sustained upward or lateral deviation of the eyes, rhythmic orofacial movements, backward and lateral flexions of the neck, tongue protrusion, and jaw spasms that can sometimes be confused with seizures5,6
  • Can occur several times a day or several times a week, and last from a few seconds to hours6
  • Often confused with a seizure, epilepsy, or cerebral palsy6,7 
Illustrations depicting (A) an oculogyric crisis and (B) involuntary movements that may accompany an episode
Normal EEG and neuroimaging1,2,4,8,9,a
  • History of normal EEG, MRI, or CT
  • Inconsistent with presentation
Autonomic symptoms1
  • Hyperhidrosis (65%; n=51/78)
  • Hypersalivation (41%; n=32/78)
  • Ptosis (39%; n=30/78)
  • Nasal congestion (31%; n=24/78) 
Diurnal variation2,10,11
  • Motor symptoms become exacerbated or more prominent late in the day10,11
  • Symptoms improve with sleep10,11

Common signs and symptoms

Hypotonia1

  • Present in 95% of patients (n=74/78)1
  • Most commonly reported symptom1

Developmental delays1

  • Present in 63% of patients (n=49/78)1
  • May include impairments in head control, crawling, or standing, and speech delays2,12

Movement disorders1

  • Dystonia (53%; n=41/78)
  • Hypertonia (44%; n=35/78)
  •  Hypokinesia (32%; n=25/78)
Illustration of hypotonia
Illustration depicting developmental delay and/or dystonia; lack of head control or dystonic posturing of body
Diagnosing AADC deficiency

Currently, these core tests can help diagnose AADC deficiency:2

  • CSF neurotransmitter metabolite panel(53%; n=41/78)
  • Plasma enzyme activity assay
  • Genetic testing

Current consensus guidelines recommend CSF neurotransmitter metabolite panel and/or plasma AADC enzyme activity assay in combination with genetic testing to confirm AADC deficiency.2

For further information on signs and symptoms, testing, and diagnosing AADC deficiency in your patients, visit AADCInsights.eu.

CT=computed tomography; EEG=electroencephalogram; MRI=magnetic resonance imaging

References: 1. Brun L, Ngu LH, Keng WT, et al. Clinical and biochemical features of aromatic L-amino acid decarboxylase deficiency. Neurology. 2010;75(1):64-71. 2. 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. 3. Manegold C, Hoffmann GF, Degen I, et al. Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up. J Inherit Metab Dis. 2009;32(3):371-380. 4. Zouvelou V, Yubero D, Apostolakopoulou L, et al. The genetic etiology in cerebral palsy mimics: the results from a Greek tertiary care center. Eur J Paediatr Neurol. 2019;23(3):427-437. doi:10.1016/j.ejpn.2019.02.001. 5. Hwu W-L, Lee N-C, Chien Y-H, et al. AADC deficiency: occurring in humans, modeled in rodents. Adv Pharmacol. 2013;68:273-284. 6. 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. 7. Lee W-T. Disorders of monoamine metabolism: inherited disorders frequently misdiagnosed as epilepsy. Epilepsy Seizure. 2010;3(1):147-153. doi:10.3805/eands.3.147. 8. Kurian MA, Dale RC. Movement disorders presenting in childhood. Continuum (Minneap Minn). 2016;22(4):1159-1185. 9. 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. 10. Ng J, Papandreou A, Heales SJ, et al. Monoamine neurotransmitter disorders—clinical advances and future perspectives. Nat Rev Neurol. 2015;11(10):567-584. 11. Pearson TS, Pons R, Ghaoui R, Sue CM. Genetic mimics of cerebral palsy. Mov Disord. 2019;34(5):625-636. 12. Hwu W-L, Chien Y-H, Lee N-C, et al. Natural history of aromatic L-amino acid decarboxylase deficiency in Taiwan. JIMD Rep. 2018;40:1-6. doi:10.1007/8904_2017_54.

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AE-AADC-0267 | August 2022

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Welcome to "About AADC MEA"

This website is provided for healthcare professionals residing in the Middle East and Africa.

This educational website provides information to support the early and accurate diagnosis of rare neurotransmitter disorders, including Aromatic L-amino Acid Decarboxylase (AADC) deficiency.