National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Syndactyly type 1


Other Names:
SDTY1; SD1; Zygodactyly
Categories:
This disease is grouped under:
Syndactyly type 1 is a congenital limb developmental defect that involves webbing or joining of the fingers or toes. Syndactyly type 1 is the most common type of non-syndromic syndactyly. Individuals with syndactyly type 1 have webbing of the third and fourth fingers and/or between the second and third toes. Other digits may be involved, as well as the underlying bones. There are four different subtypes of syndactyly type 1, differentiated by slightly different hand and foot symptoms.[1][2] Syndactyly type 1 may be inherited in an autosomal dominant manner and is suspected to be caused by a gene mutation on the long (q) arm of chromosome 2 between 2q34 and 2q36.[1][2][3] Treatment usually involves surgery to separate the digits.[4]
Last updated: 12/16/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Finger syndactyly 0006101
Toe syndactyly
Fused toes
Webbed toes
[ more ] 		0001770
5%-29% of people have these symptoms
Sagittal craniosynostosis
Early closure of midline skull joint
Midline skull joint closes early
[ more ] 		0004442
Symphalangism affecting the phalanges of the hand
Fused finger bones of the hand
0009773
Percent of people who have these symptoms is not available through HPO
2-3 toe syndactyly
Webbed 2nd and 3rd toes
0004691
3-4 finger syndactyly
Webbed 3rd-4th fingers
0006097
Autosomal dominant inheritance 0000006
Cutaneous syndactyly 0012725
Distal symphalangism of hands
Fused outermost bones of hand
0001204
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Last updated: 7/1/2020

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.
  • The University of California San Francisco Limb Study is researching the genetic causes of limb malformations. They are looking for participants who only have problems with their limbs, such as fused or webbed fingers/toes, more than 5 fingers/toes, less than 5 fingers/toes, split hand and foot also called ectrodactyly, short fingers/toes, bent pinky fingers, extra long fingers, flexed fingers, club foot, etc. Visit the study’s website to learn more about who is eligible to take part in this study.
  • The Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research. Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query".

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The Children's Hospital Boston provides an information page on syndactyly. Click on the link to view this page.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I was born with complete and complex syndactyly of my right hand. I would like to learn more about this and what may have caused this to happen. See answer


  1. Malik, Sajid. Syndactyly: phenotypes, genetics and current classification. Eur J Hum Genet.. August 2012; 20(8):817-824. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3400728/.
  2. Jordan, D. et al. The Epidemiology, Genetics and Future Management of Syndactyly. The Open Orthopaedics Journal. 2012; 6(Suppl 1: M2):14-27. https://benthamopen.com/FULLTEXT/TOORTHJ-6-14.
  3. Syndactyly type 1. Orphanet. May 2008; http://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=12324&Disease_Disease_Search_diseaseGroup=Syndactyly-type-1&Disease_Disease_Search_diseaseType=Pat&Disease(s)/group%20of%20diseases=Syndactyly-type-1&title=Syndactyly-type-1&search=Disease_Search_Simple.
  4. Deune, EG. Syndactyly. Medscape. November 3, 2015; http://emedicine.medscape.com/article/1244420.