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Aromatic l-amino acid decarboxylase deficiency


Aromatic l-amino acid decarboxylase (AADC) deficiency is an inherited disorder that affects the way nerve cells (neurons) transmit information to other cells.

Signs and symptoms of AADC deficiency typically appear in the first six months of life. Affected infants may have feeding problems, weak muscle tone (hypotonia), and sleep disturbances. Most children with AADC deficiency experience episodes called oculogyric crises that involve involuntary upward-rolling movements of the eyes. Additional signs and symptoms typically include developmental delays and intellectual disabilities. 

Movement disorders are common in people with AADC deficiency. Involuntary movements that can occur in people with AADC deficiency include muscle contractions that may cause unusual body positions (dystonia) and writhing movements of the limbs (athetosis). Dystonia tends to become worse when the individual is tired, but it usually improves after sleep. Affected individuals may also experience slow or diminished movements (hypokinesia). 

AADC deficiency may also affect the autonomic nervous system, which controls involuntary body processes such as the regulation of blood pressure and body temperature. This can lead to signs and symptoms such as droopy eyelids (ptosis), constriction of the pupils of the eyes (miosis), inappropriate or impaired sweating, nasal congestion, drooling, poor control of body temperature, low blood pressure (hypotension), low blood glucose (hypoglycemia), and abnormal heart rhythms.

People with AADC deficiency have an increased risk of infection, which can lead to life-threatening complications. 


AADC deficiency is a rare disorder. Approximately 350 people with this condition have been reported in the literature. The condition is more prevalent in certain Asian populations, particularly among people from Taiwan, Japan, and China.


Variants (also called mutations) in the DDC gene cause AADC deficiency. The DDC gene provides instructions for making the AADC enzyme, which plays an important role in the nervous system. Within neurons, the AADC enzyme helps produce dopamine and serotonin, which are two types of neurotransmitters. Neurotransmitters are chemical messengers that transmit important signals from neurons to other cells in the body. Dopamine can be used to create additional neurotransmitters called epinephrine and norepinephrine.

Variants in the DDC gene can reduce the activity of the AADC enzyme. This causes neurons to produce less dopamine and serotonin than normal, which in turn reduces the production of epinephrine and norepinephrine. Changes in the levels of these four neurotransmitters contribute to the developmental delays, intellectual disabilities, abnormal movements, and autonomic nervous system dysfunction seen in people with AADC deficiency.


This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell must have a variant to cause the disorder. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

  • AADC deficiency
  • DDC deficiency
  • Dopa decarboxylase deficiency

Additional Information & Resources

Genetic and Rare Diseases Information Center

Patient Support and Advocacy Resources

Clinical Trials

Catalog of Genes and Diseases from OMIM

Scientific Articles on PubMed


  • Blau N, Pearson TS, Kurian MA, Elsea SH. Aromatic L-Amino Acid Decarboxylase Deficiency. 2023 Oct 12. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from Citation on PubMed
  • Brun L, Ngu LH, Keng WT, Ch'ng GS, Choy YS, Hwu WL, Lee WT, Willemsen MA, Verbeek MM, Wassenberg T, Regal L, Orcesi S, Tonduti D, Accorsi P, Testard H, Abdenur JE, Tay S, Allen GF, Heales S, Kern I, Kato M, Burlina A, Manegold C, Hoffmann GF, Blau N. Clinical and biochemical features of aromatic L-amino acid decarboxylase deficiency. Neurology. 2010 Jul 6;75(1):64-71. doi: 10.1212/WNL.0b013e3181e620ae. Epub 2010 May 26. Erratum In: Neurology. 2010 Aug 10;75(6):576. Dosage error in article text. Citation on PubMed
  • Hyland K. Inherited disorders affecting dopamine and serotonin: critical neurotransmitters derived from aromatic amino acids. J Nutr. 2007 Jun;137(6 Suppl 1):1568S-1572S; discussion 1573S-1575S. doi: 10.1093/jn/137.6.1568S. Citation on PubMed
  • Lee HC, Lai CK, Yau KC, Siu TS, Mak CM, Yuen YP, Chan KY, Tam S, Lam CW, Chan AY. Non-invasive urinary screening for aromatic L-amino acid decarboxylase deficiency in high-prevalence areas: a pilot study. Clin Chim Acta. 2012 Jan 18;413(1-2):126-30. doi: 10.1016/j.cca.2011.09.008. Epub 2011 Sep 21. Citation on PubMed
  • Pearl PL, Capp PK, Novotny EJ, Gibson KM. Inherited disorders of neurotransmitters in children and adults. Clin Biochem. 2005 Dec;38(12):1051-8. doi: 10.1016/j.clinbiochem.2005.09.012. Epub 2005 Nov 18. Citation on PubMed
  • Pearl PL, Taylor JL, Trzcinski S, Sokohl A. The pediatric neurotransmitter disorders. J Child Neurol. 2007 May;22(5):606-16. doi: 10.1177/0883073807302619. Citation on PubMed
  • Pons R, Ford B, Chiriboga CA, Clayton PT, Hinton V, Hyland K, Sharma R, De Vivo DC. Aromatic L-amino acid decarboxylase deficiency: clinical features, treatment, and prognosis. Neurology. 2004 Apr 13;62(7):1058-65. doi: 10.1212/wnl.62.7.1058. Citation on PubMed
  • Swoboda KJ, Saul JP, McKenna CE, Speller NB, Hyland K. Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes. Ann Neurol. 2003;54 Suppl 6:S49-55. doi: 10.1002/ana.10631. Citation on PubMed
  • Verbeek MM, Geurtz PB, Willemsen MA, Wevers RA. Aromatic L-amino acid decarboxylase enzyme activity in deficient patients and heterozygotes. Mol Genet Metab. 2007 Apr;90(4):363-9. doi: 10.1016/j.ymgme.2006.12.001. Epub 2007 Jan 19. Citation on PubMed
  • Wassenberg T, Molero-Luis M, Jeltsch K, Hoffmann GF, Assmann B, Blau N, Garcia-Cazorla A, Artuch R, Pons R, Pearson TS, Leuzzi V, Mastrangelo M, Pearl PL, Lee WT, Kurian MA, Heales S, Flint L, Verbeek M, Willemsen M, Opladen T. Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency. Orphanet J Rare Dis. 2017 Jan 18;12(1):12. doi: 10.1186/s13023-016-0522-z. Citation on PubMed

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