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Disease Profile

Syndactyly type 2

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.



US Estimated


Europe Estimated

Age of onset




Q70.0 Q70.2


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)

Synpolydactyly; SPD


The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 93403

Syndactyly type 2 or synpolydactyly (SPD) is a rare congenital distal limb malformation characterized by the combination of syndactyly and polydactyly.

The prevalence is unknown.

Clinical description
In most cases, SPD affects the 3rd and 4th fingers and the 4th and 5th toes, bilaterally. Additional features include 5th finger clinodactyly, camptodactyly and/or brachydactyly.

Three loci have been identified: SPD1(HOXD13 gene, 2q31 locus), SPD2 (FBLN1 gene; 22q13.31) and SPD3 (14q11.2-q12).

Genetic counseling
SPD is inherited in an autosomal dominant manner.

Visit the Orphanet disease page for more resources.


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
2-3 toe syndactyly
Webbed 2nd and 3rd toes
3-4 finger syndactyly
Webbed 3rd-4th fingers
30%-79% of people have these symptoms
Abnormality of the metacarpal bones
Abnormality of the long bone of hand
Camptodactyly of finger
Permanent flexion of the finger
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
Postaxial foot polydactyly
Extra toe attached near the little toe
Short foot
Short feet
Small feet

[ more ]

Short palm
Symphalangism affecting the phalanges of the hand
Fused finger bones of the hand
5%-29% of people have these symptoms
Mesoaxial polydactyly
Preaxial foot polydactyly
Sandal gap
Gap between 1st and 2nd toes
Gap between first and second toe
Increased space between first and second toes
Sandal gap between first and second toes
Wide space between 1st, 2nd toes
Wide space between first and second toes
Wide-spaced big toe
Widely spaced 1st-2nd toes
Widely spaced first and second toes
Widened gap 1st-2nd toes
Widened gap first and second toe

[ more ]

Percent of people who have these symptoms is not available through HPO
2nd-5th toe middle phalangeal hypoplasia
Underdeveloped 2nd-5th middle toe bones
4-5 toe syndactyly
Webbed 4th-5th toes
6 metacarpals
6 long bones of hand
Autosomal dominant inheritance
Broad hallux
Broad big toe
Wide big toe

[ more ]

Contracture of the proximal interphalangeal joint of the 5th finger
Finger syndactyly
Mesoaxial hand polydactyly
Short middle phalanx of the 5th finger
Short middle bone of the little finger
Short middle bone of the pinkie finger
Short middle bone of the pinky finger

[ more ]

Y-shaped metacarpals
Y-shaped long bone 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

  • 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

  • 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.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Syndactyly type 2. Click on the link to view a sample search on this topic.