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Hitchhiker's thumb

Inherited trait where the thumb can bend backwards up to 90°

Field	Value
name	Hitchhiker's thumb
synonyms	Distal hyperextensibility of the thumb, thumb hypermobility, Z-shaped deformity, duck-bill thumb
image	Bilateral Hitchhikers Thumbs.jpg
caption	Bilateral hitchhiker's thumb
field	Medical genetics
symptoms	A thumb joint that can bend backwards beyond the normal range of motion, up to a 90° degree angle
complications	Typically none, but may be associated with genetic diseases
duration	Lifelong
causes	Genetic (autosomal recessive)
risks	Family history
frequency	24–36% of the U.S. population

Etymology

The trait is named hitchhiker's thumb as it resembles the hand gesture used to hitch a ride on the side of a road.

Signs and symptoms

Hitchhiker's thumb involves having a thumb with a distal phalange that is able to bend backwards beyond the normal range of motion (50°), up to an angle of 90°. Some people with hitchhiker's thumb also have a Z-shaped deformity, named after the appearance of this deformity. The trait in itself is usually painless and does not normally affect usage of the hands.

Z-shaped deformity in a hitchhiker's thumb

Causes

Hitchhiker's thumb is a genetic trait and is inherited in an autosomal recessive manner. It may sometimes be associated with genetic diseases, including:

diastrophic dysplasia
hypermobility spectrum disorder
atelosteogenesis, type II
atelosteogenesis, type III

Incidence

Hitchhiker's thumbs affect 24–36% of the U.S. population.

References

"What Is Hitchhiker's Thumb?".
Shetty, Aditya. "Hitchhiker thumb deformity | Radiology Reference Article | Radiopaedia.org".
(May 9, 2019). "Do you have the genetics for the Hitchhiker's Thumb?".
(2022-05-18). "Hitchhiker's Thumb".

Info: 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.

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