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AADC deficiency is a rare, devastating disorder of the central nervous system

Aromatic L-amino Acid Decarboxylase (AADC) deficiency is a genetic disease associated with defects in neurotransmitter synthesis, resulting in life-limiting motor and autonomic dysfunction, developmental delay, and premature death1-3

  • AADC deficiency can manifest with a broad spectrum of symptoms. The most common are1-3:
    • Hypotonia 
    • Developmental delay
    • Movement disorders, especially oculogyric crisis
  • In the published consensus guidelines:
    • Mean age of onset for patients with AADC deficiency is 2.7 months (n=68)2
    • Despite this young age of symptom onset, the mean age of diagnosis is 3.5 years (n=68)

Symptoms typically do not improve, leading to the need for lifelong care1,3

  • Patients who live to adulthood suffer long-term cardiac and orthopedic complications and increased risk of infections2
  • Body weight may be normal in the first few months, but growth and weight gain can slow after the first year

AADC deficiency can affect patients of any gender, ethnic origin, or geographic region2,4

AADC deficiency has been reported in individuals of Asian, Caucasian, Arabic, Iranian, and Jewish ethnic origin2,a

  1. Based on 117 patients with AADC deficiency as reported in a literature review.2

AADC is an enzyme required for biosynthesis of dopamine and serotonin2,3,5,6

  • In the autosomal recessive disease AADC deficiency, mutations in the dopa decarboxylase (DDC) gene result in reduced AADC enzyme activity, leading to severe combined deficiency of the neurotransmitters dopamine, serotonin, norepinephrine, and epinephrine2,3,5,6
  • The result is an increase in L-dopa, 3-OMD, and 5-HTP, and a decrease in the neurotransmitter metabolites HVA and 5-HIAA2,3,5,6
The clinical course of AADC eficiency
The clinical course of AADC Deficiency

Adapted from Wassenberg 2017.2

3-OMD=3-O-methyldopa; 5-HIAA=5-hydroxyindoleacetic acid; 5-HTP=5-hydroxytryptophan; HVA=homovanillic acid; L-dopa=L-3,4-dihydroxyphenylalanine; VLA=vanillactic acid.

97% failed to achieve motor milestones1,4

Based on a natural history study of 37 patients diagnosed with AADC deficiency


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References: 1. 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. 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. 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. 4. Hwu WL, Chien YH, Lee NC, 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. 5. 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. 6. Hwu WL, Lee NC, Chien YH, et al. AADC deficiency: occurring in humans, modeled in rodents. Adv Pharmacol. 2013;68:273-284.