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Brachydactyly

Abnormally short fingers or toes

Summary

Abnormally short fingers or toes

Field	Value
name	Brachydactyly
image	Brachydactyly.svg
caption	Different forms of brachydactyly

Brachydactyly () is a medical term denoting the presence of abnormally short digits (fingers or toes) at birth. The shortness is relative to the length of other long bones and other parts of the body. Brachydactyly is an inherited, dominant trait. It most often occurs as an isolated dysmelia, but can also occur with other anomalies as part of many congenital syndromes. Brachydactyly may also be a signal that one is at risk for congenital heart disease due to the association between congenital heart disease and Carpenter syndrome and the link between Carpenter syndrome and brachydactyly.

Nomograms for normal values of finger length as a ratio to other body measurements have been published. In clinical genetics, the most commonly used index of digit length is the dimensionless ratio of the length of the third (middle) finger to the hand length. Both are expressed in the same units (centimeters, for example) and are measured in an open hand from the fingertip to the principal creases where the finger joins the palm and where the palm joins the wrist.

Causes

Generally, brachydactyly is inherited through an autosomal dominant trait (The exact gene may differ see "Types" table for specific genes). However exceptions could exist due to antiepileptic medicines taken during pregnancy or low blood flow to the extremities during infancy.

Symptoms

Symptoms of isolated brachydactyly include shorter bones in the hands and feet. This could include, phalanges, metacarpals, metatarsals, carpals, and tarsals. Different types of isolated brachydactyly have different symptoms and they are grouped according to what areas they affect.

Prognosis

Isolated brachydactyly does not affect the wellbeing nor longevity of one's life, in most cases treatment is not necessary. The trait is primarily a cosmetic one and does not, in most cases, affect function of the hands and feet. Even left untreated and affecting function the general diagnosis of brachydactyly does not impact life expectancy. Prognosis may differ with different types or syndromes. ie. brachydactyly-mesomelia-intellectual disability-heart defects syndrome or if brachydactyly is not isolated and is a part of a larger genetic condition. In rare cases of isolated untreated brachydactyly, simple functions like walking or grabbing objects may be difficult, reducing the overall quality of life.

Treatment

Treatment is needed only if brachydactyly affects the function of the phalanges. In rare cases where function is affected, reconstructive surgery is used to improve function and the ability to use one's phalanges. Cosmetic surgery (which is often confused with reconstructive surgery, but differs in that cosmetic surgery is not medically necessary, while reconstructive is) changes the way the affected areas appear.

Diagnosis

Brachydactyly is usually diagnosed through anthropometric, clinical, or radiological methods. It is usually found early during infancy or in childhood years when the size difference becomes noticeable. It normally gets diagnosed as the difference in phalange size becomes more apparent. Healthcare providers complete a medical history, physical exam of symptoms and use radiographs (X-rays). The X-rays show whether certain bones are shorter than others or shorter than they are expected to be. Along with these diagnostic steps, the healthcare provider may conduct a genetic test. This could be to see if the disorder runs in the family and has been passed down or to identify the defective gene.

Epidemiology

Most isolated forms of brachydactyly are considered rare, that is, diseases affecting fewer than 200,000 people. However, type A3 and type D are relatively common, affecting around 2% of the population. Particularly high prevalence of brachydactyly type D was reported among Israeli Arabs and in the Japanese population. Type A3 was found at an especially high frequency of 21% among Japanese schoolchildren.

Types

There are several types of brachydactyly:

Type	OMIM	Gene	Locus	Also known as
Description
Type A1, BDA1	{{OMIM	112500	none}}	IHH BDA1B	5p13.3-p13.2, 2q33-q35
Type A2, BDA2	{{OMIM	112600	none}}	BMPR1B GDF5	20q11.2, 4q23-q24
Type A3, BDA3	{{OMIM	112700	none}}	HOXD13
Type A4, BDA4	{{OMIM	112800	none}}	HOXD13	2q31-q32
Type A5, BDA5	{{OMIM	112900	none}}
Type A6, BDA6	{{OMIM	112910	none}}
Type A7, BDA7				Brachydactyly type A7 or brachydactyly smorgasbord type.
Type B, BDB (or BDB1)	{{OMIM	113000	none}}	ROR2	9q22
Type C, BDC	{{OMIM	113100	none}}	GDF5	20q11.2
Type D, BDD	{{OMIM	113200	none}}	HOXD13	2q31-q32
Type E, BDE	{{OMIM	113300	none}}	HOXD13	2q31-q32
Type B and E	{{OMIM	112440	none}}	ROR2 HOXD13	9q22, 2q31-q32
Type A1B, BDA1B	{{OMIM	607004	none}}		5p13.3-p13.2

Other syndromes

In the above brachydactyly syndromes, short digits are the most prominent of the anomalies, but in many other syndromes (Down syndrome, Rubinstein–Taybi syndrome, etc.), brachydactyly is a minor feature compared to the other anomalies or problems comprising the syndrome.

References

(2018-11-20). "Genetic Basis for Congenital Heart Disease: Revisited". Circulation.
(2007-06-01). "RAB23 Mutations in Carpenter Syndrome Imply an Unexpected Role for Hedgehog Signaling in Cranial-Suture Development and Obesity". The American Journal of Human Genetics.
(2012). "Antiepileptic drugs and pregnancy outcomes". American Journal of Medical Genetics Part A.
"Brachydactyly Types - Causes & Outlook".
"Rare Diseases FAQ".
(2008-06-13). "Brachydactyly". Orphanet Journal of Rare Diseases.
Temtamy, Samia. (1978). ""The genetics of hand malformations."". Birth Defects Original Article Series.
Idengaku Zasshi, Jinrui. (1962). "The Japanese journal of human genetics". The Japanese Journal of Human Genetics.
Brennan, Dan. "What Is Brachydactyly?".
(1989). "Brachydactyly type A-7 (Smorgasbord): a new entity". Clin. Genet..
(15 July 2021). "Clubbing of the Nails: Background, Pathophysiology, Epidemiology".

Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

congenital-disorders-of-musculoskeletal-system

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