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

DDX gene family

Reviewed February 2014

What are the DDX genes?

Genes in the DDX gene family provide instructions for making enzymes that function as helicases. Helicases attach (bind) to DNA or its chemical cousin, RNA, and temporarily unwind the two spiral strands (double helix) of these molecules. While a few DDX helicases associate with DNA, these proteins primarily bind to RNA molecules.

Helicases in the DDX family contain a specific sequence of protein building blocks (amino acids) in one region of the protein. Using the one-letter abbreviations for the sequence of asparagine (D), glutamic acid (E), alanine (A), and asparagine (D), this sequence is known as a "DEAD" box.

DDX helicases are normally in an "open" position and not bound to RNA or DNA. With the aid of the DEAD box, a DDX helicase attaches to a molecule called ATP, causing the helicase to close around the RNA or DNA molecule and prompting it to unwind. Once the unwinding is complete, the DDX helicase releases both molecules and opens again.

DDX helicases often have other functions in addition to unwinding RNA or DNA. They usually function as part of larger groups of proteins that work together (complexes). These complexes aid in proper RNA folding, assembly or disassembly of RNA complexes, properly piecing together RNA, and breaking down RNA that is no longer needed. DDX helicases may also play a role in repairing mistakes in DNA and ensuring normal copying of DNA (DNA replication).

Mutations in one DDX gene, DDX11, have been found to cause a very rare condition called Warsaw breakage syndrome. These mutations lead to problems with cell division and an accumulation of DNA damage. People with this condition have multiple abnormalities, which may include impaired growth, distinctive facial features, hearing loss, and heart malformations, although it is unclear how DDX11 gene mutations lead to these features.

Which genes are included in the DDX gene family?

The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families ( and their member genes.

Genetics Home Reference summarizes the normal function and health implications of this member of the DDX gene family: DDX11.

What conditions are related to genes in the DDX gene family?

Genetics Home Reference includes these conditions related to genes in the DDX gene family:

  • Warsaw breakage syndrome

Where can I find additional information about the DDX gene family?

You may find the following resources about the DDX gene family helpful.

  • InterPro: DNA/RNA helicase, DEAD/DEAH box type, N-terminal ( (EMBL-EBI)
  • Madame Curie Bioscience Database: RNA Helicases ( (U.S. National Library of Medicine)

What glossary definitions help with understanding the DDX gene family?

acids ; alanine ; asparagine ; ATP ; cell ; cell division ; DNA ; DNA damage ; DNA replication ; double helix ; gene ; glutamic acid ; helicase ; molecule ; protein ; RNA ; syndrome

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


These sources were used to develop the Genetics Home Reference summary for the DDX gene family.

  • Linder P, Jankowsky E. From unwinding to clamping - the DEAD box RNA helicase family. Nat Rev Mol Cell Biol. 2011 Jul 22;12(8):505-16. doi: 10.1038/nrm3154. Review. (
  • Hilbert M, Karow AR, Klostermeier D. The mechanism of ATP-dependent RNA unwinding by DEAD box proteins. Biol Chem. 2009 Dec;390(12):1237-50. doi: 10.1515/BC.2009.135. Review. (
  • Putnam AA, Jankowsky E. DEAD-box helicases as integrators of RNA, nucleotide and protein binding. Biochim Biophys Acta. 2013 Aug;1829(8):884-93. doi: 10.1016/j.bbagrm.2013.02.002. Epub 2013 Feb 15. Review. (
  • Gustafson EA, Wessel GM. DEAD-box helicases: posttranslational regulation and function. Biochem Biophys Res Commun. 2010 Apr 23;395(1):1-6. doi: 10.1016/j.bbrc.2010.02.172. Epub 2010 Mar 3. Review. (


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: February 2014
Published: February 1, 2016