The genetics of the white horse unraveled

Jul 20, 2008

The white horse is an icon for dignity which has had a huge impact on human culture across the world. An international team led by researchers at Uppsala University has now identified the mutation causing this spectacular trait and show that white horses carry an identical mutation that can be traced back to a common ancestor that lived thousands of years ago. The study is interesting for medical research since this mutation also enhance the risk for melanoma. The paper is published on July 20 on the website of Nature Genetics.

The great majority of white horses carry the dominant mutation Greying with age. A Grey horse is born coloured (black, brown or chestnut) but the greying process starts already during its first year and they are normally completely white by six to eight years of age but the skin remains pigmented.

Thus, the process resembles greying in humans but the process is ultrafast in these horses. The research presented now demonstrates that all Grey horses carry exactly the same mutation which must have been inherited from a common ancestor that lived thousands of years ago.

It is a fascinating thought that once upon a time a horse was born that turned grey and subsequently white and the people that observed it were so fascinated by its spectacular appearance that they used the horse for breeding so that the mutation could be transmitted from generation to generation, says Leif Andersson who led the study. Today about one horse in ten carries the mutation for Greying with age.

It is obvious that humans across the world have greatly valued these white horses as documented by the rich collection of stories and paintings featuring white horses. In the paper the white horse as an icon for dignity is illustrated by reproducing a painting from the late 17th century of the Swedish king Karl XI on his white horse Brilliant.

The Grey horse is also very interesting from a medical point of view since the mutation also predisposes for development of melanoma. About 75% of Grey horses older than 15 years of age have a benign form of melanoma that in some cases develops into a malignant melanoma. Thus, the study reported today has also given new insight in a molecular pathway that may lead to tumour development.

We propose that the Grey mutation stimulates growth of melanocytes and that this leads to a premature loss of the melanocyte stem cells needed for hair pigmentation whereas the mutation promotes an expansion of some of the melanocytes causing skin pigmentation, says Leif Andersson.

Domestic animals constitute extraordinary models for evolution of biological diversity as already recognized by Charles Darwin. The white horse is a beautiful illustration of the importance of regulatory mutations as a major underlying mechanism for phenotypic diversity within and between species. The Grey mutation does not change any protein structure but it affects the genetic regulation of two genes. The researchers found that the white horses carry an extra copy of a DNA segment located in one of these genes.

It is very likely that regulatory mutations like the one we found in these white horses constitute the dominating class of mutations explaining differences between breeds of domestic animals as well as between species like humans and chimpanzee, concludes Leif Andersson.

Source: Uppsala University

Explore further: Scientist discovers populations of rare songbird in surprising new habitat

add to favorites email to friend print save as pdf

Related Stories

Guarding the country against foreign animal diseases

Oct 25, 2013

A deadly animal virus is on the loose, treading through Russia and knocking on the doors of Eastern Europe and Asia. After its introduction into the Republic of Georgia and the Caucasus region in 2007 and ...

Rare white horse prancing around in his own special genes

Jun 01, 2012

There was no hanky-panky involved when a fairy-tale white foal was born to two brown Standardbreds at the Four Winds Farm in New Jersey. DNA tests confirm that the snowy foal, born May 6, is a mutant, but that's nothing to ...

Cancer activist's approach: Real, a bit irreverent

Oct 17, 2010

(AP) -- Lindsay Avner is no shrinking violet. She's a bright pink whirlwind, with a closet full of dresses cut from that very color and a cancer-fighting organization she named for it.

Scientists hope to unlock mysteries of proteins

Apr 14, 2009

Proteins, the work-horse molecules necessary for virtually every human action from breathing to thinking, have proved an almost ghostly presence, daring scientists to fully grasp their structure and behavior. Now, physicists ...

Recommended for you

Cell division, minus the cells

1 hour ago

(Phys.org) —The process of cell division is central to life. The last stage, when two daughter cells split from each other, has fascinated scientists since the dawn of cell biology in the Victorian era. ...

Scientist creates automatic birdsong recognition app

1 hour ago

Dr Dan Stowell, an EPSRC Research Fellow in QMUL's School of Electrical Engineering and Computer Science, has used a grant from Queen Mary Innovation to develop a prototype for an app that turns his research ...

A new method simplifies the analysis of RNA structure

1 hour ago

To understand the function of an RNA molecule, similar to the better-known DNA and vital for cell metabolism, we need to know its three-dimensional structure. Unfortunately, establishing the shape of an RNA ...

New research reveals fish are smarter than we thought

2 hours ago

(Phys.org) —A new study from researchers in our Department of Psychology with colleagues at Queen Mary University of London has reported the first evidence that fish are able to process multiple objects ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

nilbud
1 / 5 (1) Jul 20, 2008
My friend Flicka was enough for me "icon of dignity" seems a bit overblown.
DeeSmith
not rated yet Jul 21, 2008
Pure white horses were a relatively rare mutation and thus valuable (as were pure black horses). Because of this value, they were used often by royalty and military leaders because they were easily seen by troops at distance.

The white horse was also an ancient sacred symbol, reverence for purity of thought/action (saints/deified leaders) and power. In Christianity, the first of the Four Horseman of the Apocalypse to appear would be a rider on a white horse, signifying triumphant warfare (the others being accompaniments of war: stife, famine, and disease).

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.