Rare Immunology News

Disease Profile

Brachydactyly type A2

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






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)

BDA2; Mohr-Wriedt type brachydactyly; Brachymesophalangy 2


Congenital and Genetic Diseases; Musculoskeletal Diseases


Brachydactyly type A2 is a very rare condition affecting the middle bone (middle phalanx) of the index finger and the second toe. Typically, people affected by brachydactyly type A2 have very short (hypoplastic) middle bones of these digits. In some individuals, the bone above the middle phalanx (distal phalanx) is shifted as well, so that the fingers and toes may look misshapen. There have not been reports of other symptoms associated with brachydactyly type A2. Typically, brachydactyly type A2 does not require surgery, and affected individuals are able to use their hands normally.[1][2]


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
Type A2 brachydactyly
Short index fingers and second toes
30%-79% of people have these symptoms
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
Short foot
Short feet
Small feet

[ more ]

5%-29% of people have these symptoms
Aplasia/Hypoplasia of the middle phalanx of the 2nd finger
Absent/small middle index finger bone
Absent/underdeveloped middle index finger bone

[ more ]

Short 2nd metacarpal
Shortened 2nd long bone of hand
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 ]

Percent of people who have these symptoms is not available through HPO
2-3 toe syndactyly
Webbed 2nd and 3rd toes
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 ]

Autosomal dominant inheritance
Broad hallux
Broad big toe
Wide big toe

[ more ]

Hallux valgus
Medially deviated second toe
Radial deviation of the 2nd finger
Short 2nd finger
Short index finger
Short index fingers

[ more ]

Short hallux
Short big toe
Triangular shaped middle phalanx of the 2nd finger
Triangular shaped middle bone of index finger
Triangular shaped middle phalanx of the 5th finger
Triangular shaped middle little finger bone
Triangular shaped middle pinkie finger bone
Triangular shaped middle pinky finger bone

[ more ]

Ulnar deviation of the 2nd finger


Brachydactyly type A2 is typically diagnosed by physical examination. A clinician may look at the hands and feet and determine that they seem to match what is commonly seen in brachydactyly type A2. X-ray may be used to get a better view of the bones in the fingers and toes. Genetic testing is typically not completed to confirm the diagnosis unless one is participating in a clinical trial.[3] 

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

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.

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 Brachydactyly type A2. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

  • The Orphanet Journal of Rare Diseases has published an article with information on this condition. This journal is affiliated with the Orphanet reference portal for information on rare diseases and orphan drugs.


  1. McKusick, VA, O'Neill, MJF, Hamosh, A, and Kniffin, CL. Brachydactyly, Type A2, ; BDA2. Online Mendelian Inheritance in Man (OMIM). March 20, 2013; https://www.omim.org/entry/112600.
  2. Liu, X, Gao, L, Zhao, A, Zhang, R, Ji, B, Wang, L, Zheng, Y, Zeng, B, Valenzuela, RK,He, L, and JMa. Identification of Duplication Downstream of BMP2 in a Chinese Family with Brachydactyly Type A2 (BDA2). PLoS One. April 7, 2014; 9(4):e94201. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978006/.
  3. Temtamy SA and MS Aglan. Brachydactyly. Orphanet Journal of Rare Diseases. June 13, 2008; 3(15):https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2441618/.

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