Brachydactyly ,also known as BD, is derived from Greek roots that mean “short digits”. It is an autosomal dominant disorder that results in stubby fingers and toes. The condition is caused by shortening of the bones in the hands and feet, and in some cases people may also have a missing hand or foot bone. According to the NIH Office of Rare Diseases Research, the most common form of brachydactyly is type D, which results in a stub or “clubbed” thumb ^[1].

In 2008, the Orphanent Journal of Rare Diseases described brachydactyly as, “a general term that refers to disproportionately short fingers and toes, and forms part of the group of limb malformations characterized by bone dysostosis” ^[2]. Brachydactyly is the broader term for abnormalities in digits, and consists of subcategories that describe specific mutations. The Orphanent Journal of Rare Diseases furthermore found that the most common types that are found are the various forms of type A and type D ^[3]. Other hand malformations are known to accompany brachydactyly. These include syndactyly and symphalangism. In syndactyly, there is a web lining between digits, and in symphalangism, fingers are fused together ^[4].

Brachydactyly is an autosomal dominant mutation, and is frequently inherited through families. It is not associated with any specific medical conditions, however, the physical attributes that accompany brachydactyly are prevalent among those who have congenital diseases ^[5]. According to the NIH Office of Rare Diseases Research, recent discoveries have linked brachydactyly type B specifically to mutations in the ROR2 chromosome, which provides the blueprint for proper growth in bones ^[6].

The most common used system to differentiate the types of brachydactyly is known as the Bell Classification System, developed by Dr. Julia Bell in 19516. Although there have been modifications made to the system since its publication, it is still the most reputable and widely used today. ^[7]

TYPE A: In type A, the middle phalanges of one, several, or all of the fingers or toes are shortened. This form of BD is further divided into types A1, A2, and A3. In type A1, the middle phalanges of all digits and the proximal phalanges of the thumbs and great toes are shortened. People with this form of BD generally have hands and feet that appear small with relatively equal shortening of all digits. In type A2, the middle phalanges of the index finger and second toe are shortened and often abnormally shaped. In type A3, the middle phalanx of the fifth finger is shortened and this finger often bends toward the fourth finger. Several other forms of BD type A have also been described.

TYPE B: In type B, the distal phalanges and nails of the fingers and/or toes are small or absent. The middle phalanges may also be shortened, and the tips of the thumbs and/or great toes may be broad or have a "duplicated" (double) appearance. In this type of BD, the digits typically look as though their tips have been amputated.

TYPE C: In type C, the middle phalanges of all of the fingers may be shortened, but the fourth finger is least affected and is often the longest finger. The index and middle fingers may be bent toward the fourth finger. The first metacarpal bone can also be short, making the thumb appear small.

TYPE D: In type D, the distal phalanges of the thumbs or great toes are shortened and broad. Also known as “clubbed thumbs.”

TYPE E: In type E, the metacarpals and/or metatarsals are shortened. The fourth and fifth metacarpals and metatarsals are most commonly shortened, but any of them may be affected. ^[8]

Because cases of brachydactyly are neither life threatening nor inhibiting, there is no treatment or procedure to cure types of this disease. For those affected by brachydactyly that have significant impairments with their grip or holding objects, physical therapy is a common treatment that can assist them in living with stubby fingers. Furthermore, in severe cases, plastic surgery is available to correct the formation of digits, however this is usually done when there are inhibitions to entire hand function or for cosmetic reasons. ^[9]

Brachydactyly type D, also known as “clubbed thumbs”, is the most prominent form of brachydactyly. Characteristically, the distal phalanx of the thumb alone is shortened. ^[10] According to Abnormal Skeletal Phenotypes: from Simple Signs to Complex Diagnose, there is a distinct prevalence in clubbed thumbs within the Israelli Arab and Japanese population. ^[11] Those with brachydactyly type D possess a broad and short distal phalanx of one or both thumbs, unilateral or bilateral. They are stubby, with a wide and flat nail, and such traits may be additionally exhibited in the individual’s big toes.

Brachydactyly type D has been the subject of much fascination over the years due to the obscure shape in the thumb of those who have the mutation. In The Hand as a Mirror of Systemic Disease, author Dr. Theodore J. Berry of the University of Pennsylvania draws awareness to past misconceptions about those who had clubbed thumbs. For example, Time Magazine reported that a clubbed thumb was “a clear indication of a ‘murderer’s thumb’”, and was believed to belong to criminals. ^[12]

In addition, Megan Fox, a prominent Hollywood actress known for her roles in movies such as “ Transformers”, gained notoriety when the media began to focus on her clubbed thumbs. Images of her thumbs have since gone viral over the internet, and the New York Daily News covered the story of how her clubbed thumbs were attempted to be concealed in a particular commercial for Motorola.

"After Fox's promotional movie photos surfaced last summer, revealing a candid look at her abnormally shaped thumbs, the Daily News learned that the 23-year-old actress has a hereditary defect known as brachydactyly. 'Literally, what it means is short finger,' Dr. Steven Bendner, a hand surgeon at Beth Israel Medical Center, told us. 'The nail of the thumb in this condition is often very short and wide.' …'It is usually hereditary. Although it could also have been caused by frostbite, or it could have been an injury to the growth plate in childhood…in Megan Fox's case, it appears that only the last bone of the thumb is affected and that it does not involve the joint," says Dr. Richard Kim, director of congenital hand surgery at Hackensack Medical Center. 'For her, it looks like it's just a cosmetic deficit.'" ^[13]

Castriota-Scanderbeg, Alessandro, and Bruno Dallapiccola. Abnormal Skeletal Phenotypes: from Simple Signs to Complex Diagnoses. Berlin: Springer, 2005. 962. Print.

"Diagnosis: A Show of Hands - TIME." Breaking News, Analysis, Politics, Blogs, News Photos, Video, Tech Reviews - TIME.com. Time Magazine, 13 Mar. 1964. Web. 27 Sept. 2011. < http://www.time.com/time/magazine/article/0,9171,828275,00.html>.

Everett, Cristina, and Rosemary Black. "Brace Yourselves, Megan Fox Has an Imperfection: the Actress Is All Thumbs - New York Daily News." Featured Articles From The New York Daily News. NY Daily News, 11 June 2009. Web. 27 Sept. 2011. < http://articles.nydailynews.com/2009-06-11/gossip/17924675_1_thumb-megan-fox-clubbed>.

Everman, David B., and The Gale Group Inc. "Brachydactyly | Definition and Patient Education | Healthline." Medical Information for Healthy Living | Healthline. Healthline, 2002. Web. 27 Nov. 2011. < http://www.healthline.com/galecontent/brachydactyly>.

McKusick, Victor A. "OMIM Entry - #113200 - BRACHYDACTYLY, TYPE D; BDD." OMIM - Online Mendelian Inheritance in Man. Online Mendelian Inheritance in Man, 4 June 1986. Web. 27 Sept. 2011. < http://omim.org/entry/113200>.

"Question and Answers." NIH Office of Rare Diseases Research (ORDR). National Institutes of Health, 6 June 2011. Web. 27 Sept. 2011. < http://rarediseases.info.nih.gov/GARD/QnASelected.aspx?diseaseID=985>.

Temtamy, Samia A., and Mona S. Aglan. "Full Text | Brachydactyly." Orphanet Journal of Rare Diseases. BioMed Central Ltd., 13 June 2008. Web. 27 Sept. 2011. < http://www.ojrd.com/content/3/1/15>.

University of Florida. "Hand Malformations." University of Florida. University of Florida Department of Pediatrics Division of Genetics and Metabolism. Web. 27 Sept. 2011. < http://www.peds.ufl.edu/divisions/genetics/teaching/hand_malformations.htm>.