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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed May 2008

What is the official name of the DDC gene?

The official name of this gene is “dopa decarboxylase.”

DDC is the gene's official symbol. The DDC gene is also known by other names, listed below.

What is the normal function of the DDC gene?

The DDC gene provides instructions for making the aromatic l-amino acid decarboxylase (AADC) enzyme, which is important in the brain and nervous system. This enzyme takes part in the pathway that produces dopamine and serotonin, which are chemical messengers that transmit signals between nerve cells (neurotransmitters).

Dopamine is produced from the protein building block (amino acid) tyrosine, and serotonin is produced from the amino acid tryptophan. Both neurotransmitters are produced in two-step processes. First, other enzymes control the reactions that convert tyrosine to L-dopa, and tryptophan to 5-hydroxytryptophan. The AADC enzyme then converts L-dopa and 5-hydroxytryptophan to dopamine and serotonin, respectively. To do this, it removes a molecular structure called a carboxyl group, consisting of a carbon atom, two oxygen atoms, and a hydrogen atom.

How are changes in the DDC gene related to health conditions?

aromatic l-amino acid decarboxylase deficiency - caused by mutations in the DDC gene

Mutations in the DDC gene result in reduced activity of the AADC enzyme. Without enough of this enzyme, nerve cells produce less dopamine and serotonin. Dopamine and serotonin are necessary for normal nervous system function, and changes in the levels of these neurotransmitters contribute to the developmental delay, intellectual disability, abnormal movements, and autonomic dysfunction seen in people with AADC deficiency.

other disorders - associated with the DDC gene

Studies have shown certain variations (polymorphisms) in the DDC gene to be associated with increased risk of nicotine dependence, schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder; however, other studies have not supported these findings. Many genetic and environmental factors are believed to contribute to these complex conditions.

Where is the DDC gene located?

Cytogenetic Location: 7p12.2

Molecular Location on chromosome 7: base pairs 50,458,436 to 50,565,457

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The DDC gene is located on the short (p) arm of chromosome 7 at position 12.2.

The DDC gene is located on the short (p) arm of chromosome 7 at position 12.2.

More precisely, the DDC gene is located from base pair 50,458,436 to base pair 50,565,457 on chromosome 7.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about DDC?

You and your healthcare professional may find the following resources about DDC helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the DDC gene or gene products?

  • AADC
  • aromatic L-amino acid decarboxylase
  • dopa decarboxylase (aromatic L-amino acid decarboxylase)

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding DDC?

amino acid ; atom ; attention deficit hyperactivity disorder ; bipolar disorder ; carboxyl ; carboxyl group ; deficiency ; developmental delay ; disability ; dopamine ; enzyme ; gene ; hyperactivity ; nervous system ; neurotransmitters ; nicotine ; oxygen ; protein ; schizophrenia ; tryptophan ; tyrosine

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Hyland K, Surtees RA, Rodeck C, Clayton PT. Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis. Neurology. 1992 Oct;42(10):1980-8. (
  • 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. (
  • NCBI Gene (
  • Pearl PL, Capp PK, Novotny EJ, Gibson KM. Inherited disorders of neurotransmitters in children and adults. Clin Biochem. 2005 Dec;38(12):1051-8. Epub 2005 Nov 18. Review. (
  • Pearl PL, Taylor JL, Trzcinski S, Sokohl A. The pediatric neurotransmitter disorders. J Child Neurol. 2007 May;22(5):606-16. Review. (
  • 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. Epub 2007 Jan 19. (
  • Yu Y, Panhuysen C, Kranzler HR, Hesselbrock V, Rounsaville B, Weiss R, Brady K, Farrer LA, Gelernter J. Intronic variants in the dopa decarboxylase (DDC) gene are associated with smoking behavior in European-Americans and African-Americans. Hum Mol Genet. 2006 Jul 15;15(14):2192-9. Epub 2006 Jun 1. (
  • Zhang H, Ye Y, Wang X, Gelernter J, Ma JZ, Li MD. DOPA decarboxylase gene is associated with nicotine dependence. Pharmacogenomics. 2006 Dec;7(8):1159-66. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: May 2008
Published: February 8, 2016