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Disease Profile

Syndactyly type 1

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

1-5 / 10 000

US Estimated

Europe Estimated

Age of onset




Q70.0 Q70.1 Q70.2 Q70.3


Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

SDTY1; SD1; Zygodactyly


Congenital and Genetic Diseases


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]


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.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Finger syndactyly
Toe syndactyly
Fused toes
Webbed toes

[ more ]

5%-29% of people have these symptoms
Sagittal craniosynostosis
Early closure of midline skull joint
Midline skull joint closes early

[ more ]

Symphalangism affecting the phalanges of the hand
Fused finger bones of the hand
Percent of people who have these symptoms is not available through HPO
2-3 toe syndactyly
Webbed 2nd and 3rd toes
3-4 finger syndactyly
Webbed 3rd-4th fingers
Autosomal dominant inheritance
Cutaneous syndactyly
Distal symphalangism of hands
Fused outermost bones of hand

Learn more

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.


  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; https://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; https://emedicine.medscape.com/article/1244420.