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Disease Profile

Syndactyly type 9

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 / 1 000 000

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)

Syndactyly mesoaxial synostotic with phalangeal reduction; MSSD; Syndactyly Malik-Percin type


Congenital and Genetic Diseases; Musculoskeletal Diseases


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

Orpha Number: 157801

Mesoaxial synostotic syndactyly (MSSD) with phalangeal reduction is a novel and distinct form of non-syndromic syndactyly including complete syndactyly of the 3rd and 4th fingers with synostoses of the corresponding metacarpals and associated single phalanges, syndactyly of the 2nd and 3rd toes and 5th finger clinodactyly.

It has been described in two families.

The locus for this complex limb malformation was mapped to chromosome 17p13.3.

Genetic counseling
The condition is transmitted as an autosomal recessive trait.

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
Aplasia/Hypoplasia of the middle phalanges of the hand
Absent/small middle finger bone of the hand
Absent/underdeveloped middle finger bone of the hand

[ more ]

Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
Finger syndactyly
Metacarpal synostosis
Fused long bones of hand
Short hallux
Short big toe
Short palm
Short thumb
Short thumbs
Small thumbs

[ more ]

Symphalangism affecting the phalanges of the hand
Fused finger bones of the hand
30%-79% of people have these symptoms
Synostosis of carpal bones
Fusion of wrist bones
Percent of people who have these symptoms is not available through HPO
3-4 finger syndactyly
Webbed 3rd-4th fingers
Aplasia/Hypoplasia of the hallux
Absent/small big toe
Absent/underdeveloped big toe

[ more ]

Aplasia/Hypoplasia of the middle phalanx of the 2nd finger
Absent/small middle index finger bone
Absent/underdeveloped middle index finger bone

[ more ]

Aplasia/Hypoplasia of the middle phalanx of the 5th finger
Absent/small middle bone of pinky finger
Absent/underdeveloped middle bone of little finger
Absent/underdeveloped middle bone of pinkie finger
Absent/underdeveloped middle bone of pinky finger

[ more ]

Aplasia/Hypoplasia of the thumb
Absent/small thumb
Absent/underdeveloped thumb

[ more ]

Autosomal recessive inheritance
Proximal/middle symphalangism of 5th finger
Fused innermost and middle bones of little finger
Fused innermost and middle bones of pinkie finger
Fused innermost and middle bones of pinky finger

[ more ]

Single transverse palmar crease
Symphalangism affecting the phalanges of the hallux
Fused big toe bones

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 9. Click on the link to view a sample search on this topic.