PATN2 is Not the Blanket Gene - How Small Effect PATN Modifiers Really Work

PATN2 is Not the Blanket Gene - How Small Effect PATN Modifiers Really Work

Search online and you'll find some websites promoting a gene called PATN2 as the blanket causing-gene in Appaloosas, Knabstruppers and other spotted breeds. If only it were that simple!  The reality is that breeding for blankets is a little more complicated...

The evidence says that there is no 'blanket gene'

In fact, pedigree evidence shows very clearly that no single gene is responsible for blanket patterning. Instead, the data we've gathered supports the idea that blanket patterns are caused by multiple small effect modifiers, each contributing a little to the size of the blanket. The most likely explanation is the larger the blanket, the more of these modifiers the horse has inherited. 

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What is still to be discovered concerning appaloosa spotting?

This article is reproduced here with permission from the  Appaloosa Journal.   It was first featured in the November 2015 Appaloosa Journal’s Quick Genetic Question column.  This column is written every month by Dr. Rebecca Bellone as well as other members of the Appaloosa Project's research team.  For answers to some of the most frequently asked questions be sure to read the monthly column.  If you have a specific question you would like to see answered e-mail the editor of the Appaloosa Journal, Dana Russell,  at

In a few articles over this past year, we have discussed the LP gene, how it was discovered, and how to have your horses to DNA tested for it.

We also discussed that while all horses with LP have an appaloosa spotting pattern and associated characteristics, there is a tremendous amount of variability in terms of the amount of white spotting. In other words, there are appaloosa spotted horses that have a few white flecks on their rump and appaloosa spotted horses that are almost entirely white.

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A breeder's guide to the Leopard Complex gene (LP)

The vast array of coat patterns and interesting pigmentation variations exhibited by horses that carry the Leopard Complex or 'LP' gene (often referred to as the appaloosa gene) are an endless source of fascination for breeders and genetics researchers alike.

For most breeders, it's imperative to produce a quality horse that appeals to their chosen market. At the same time, being able to consistently produce horses with the most marketable coat patterns without compromising in other areas such as conformation, movement or temperament gives breeders an additional edge that can prove invaluable in today's market.

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Night blindness in the Appaloosa (CSNB)

CSNB stands for “congenital stationary night blindness”. More commonly referred to as night blindness, CSNB is the name given to any disease that is typified by

a) impaired/absent night vision
b) present at birth
c) inherited
d) non-progressive 

This term does not represent a single disorder. There are several forms of CSNB in humans and other animals. The above are the features that all these unique, yet similar types of CSNB share. 

Impaired night vision is a general description. Some forms of CSNB involve extremely impaired vision, while others are less severe. They all involve some degree of lack of rod function, thus the term “night blind”.

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Management of Night Blind Horses

Authors: Sheila Archer, Rebecca Bellone PhD, and Lynne Sandmeyer, DVM

This article is provided by members of the Appaloosa Project research team for the education of website visitors. It is protected by international copyright. No portion may be reproduced without the express written consent of the authors.

General Notes

  • Night vision is completely absent in affected horses – only the brightest of lights are visible.
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Equine Vision and Management of Vision Problems in Horses

This article is provided by Appaloosa Project research team member Dr. Lynne Sandmeyer for the education of website visitors. It is protected by international copyright law, and no part can be reproduced without the express written consent of the author.

The Basics of Vision

- Light enters and travels through the clear cornea, anterior chamber, lens, and vitreous

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Equine Recurrent Uveitis

Author: Lynne Sandmeyer DVM, DVSc, DACVO, Associate Professor Ophthalmology, University of Saskatchewan

Equine recurrent uveitis (ERU) - sometimes called “Moon blindness”, iridocyclitis, or periodic ophthalmia - is one of the oldest known ocular diseases in the horse.

It is an acquired, progressive condition and the most common cause of blindness in the horse world-wide. What follows is a summary of ERU including what it is, what may cause it, how it is recognized, and how it is treated.

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Appaloosa Project video seminars

The Appaloosa Project is delighted to present a three-part YouTube video seminar series on stacking the odds of appaloosa color in your favor for spotted horse enthusiasts.

Rebecca Bellone Ph.D. and Sheila Archer recorded this series by Skype and presented it at New Zealand's Equidays extravaganza in conjunction with Sportaloosa International.

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