Horse Color Galore! An intro to the Leopard Complex and PATN1!

 

The pattern in which Appaloosas are famous for is called Leopard Complex and it actually originates from Europe. This gene is known for it's wide expression of patterns ranging from a completely solid colored horse with Molted skin on the thin haired regions; to an almost white horse with teeny tiny colored spots and a dark mane and tail. There are so many different expressions on this gene, that it can be confusing to just wrap your mind around it. So, in turn, for this first installment of the Horse Color Galore! Color Genetics Series, we'll discuss the general knowledge and history of the gene; while explaining the different patterns in later installments.

The genotype symbol for Leopard Complex is Lp. This gene is in charge of Molted Skin, Striped Hooves, Visible Sclera, and a progressive pigment loss pattern commonly known as Varnish Roan. This gene also causes Congenital Stationary Night Blindness (CSNB) when expressed Homozygous. Now, where is all the loud spotted patterns?! That is actually caused by the combination of Lp and PATN1. PATN1 is a recently discovered gene that plays a huge part in breeding horses with the Leopard Complex. This additional enhancer gene causes the regular Lp gene to express more than 50% amounts of white, according to UC Davis. However, it is also noted that PATN1 cannot express on it's own - N/Lp (Heterozygous) or Lp/Lp (Homozygous) has to be present.

Dappled Horses at the Pech-Merle Cave, France.

Surprisingly, spotted horses have been depicted in art for several thousands of years. The oldest known display is The Dappled Horses at the Pech-Merle Cave, France, in 25,000 B.C. Since then, "spotted" horses popped up in cultural artwork and documentation throughout Northern Africa, Persia, Asia, and Europe. The spotted pattern, in short, is a mutation that occurred through domestication as a side effect to breeding for desirable traits like endurance and strength. Eventually, the new color pattern became sought out for and even royal.

Johann Georg DeHamilton's Curly Lp Lipizzaner Stallions Paintings

As with many other extravagant colors valued within the human's grasp, the urge to own a spotted horse declined as the rise for solid colored horses - therefore causing the gene to become extinct in certain breeds (such as the Lipizzaner above). However, the gene was introduced to the Americas via the Spaniards with the extinct Spanish Jennet. Just like the other horses who became loose from their grasps, their spotted horses became prized possessions of the Nimipuu natives (Nez Perce) along the Palouse River - these horses are what became the Appaloosa. Interestingly enough, in recent years, spotted horses have been making a come-back. Any breed exhibiting the Leopard Complex and the PATN1 enhancer gene, have been used to "bring back" historical breeds and colors; as well as outcrossing to create new breeds.

Breeds where the Leopard Complex is present:

Altai, American Baskir Curly, American Shetland Pony, Appaloosa, Australian Spotted Pony, British Appaloosa, British Riding Pony, British Spotted Pony, Colorado Ranger Horse, Dartmoor (present, but restricted), Falabella, Felin Pony, German Classic Pony, Gotland Pony, Gypsy Vanner Horse and Pony, Hungarian Coldblood, Karabaier, Knabstruper, Lewitzer (present, but restricted), Malopolski, Miniature Horse, Mongolian Pony, New Forest Pony (present, but restricted), Nez Perce Horse, Noriker, North American Spotted Draft Horse (present, but restricted), Pony of the Americas, American Quarter Horse (present, but restricted), Selle Français, Miniature Shetland Pony, Silesian, Spanish Colonial, Spanish Mustang, Tennessee Walking Horse, Tiger Horse,  Welsh Pony (Sections A & B), Wielkopolski, and the Yakut.

Breeds where the Leopard Complex is Historically documented, but is no longer present in the breed:

Fredricksborg, Hackney Horse and Pony, Kladruby, Lipizzaner, Morgan, Spanish Jennet (extinct), and the Welsh Cob (Sections C & D).

References:

An Almost Complete List of Breeds & Colors by Lesli Kathman file:///C:/Users/Daphne/Desktop/NewColorCharts2020.pdf 

https://dartmoorponysociety.com/the-breed/#TheBreedStandardoftheDartmoorPony

https://www.murderhollow.com/breeding-faq.html

https://vgl.ucdavis.edu/test/leopard-complex

https://www.horsetalk.co.nz/2013/10/27/leopard-complex-spotting-17000-years-research/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4275893/#:~:text=Today%2C%20leopard%20complex%20spotting%20phenotypes,Knabstrupper%2C%20Noriker%2C%20Karabaier).