Tuesday, January 24, 2023


 So....I'm often asked what is all this LP/Lp or PATN/PATN all about with Chipper? To say deciphering Appaloosa coat patterns is a challenge would be an understatement. Research is still in progress. But there are several great sites for what we know so far. The one I like is UC Davis who also performs the DNA tests for LP and PATN (1). https://vgl.ucdavis.edu/test/appaloosa-pattern-1

Through testing, we know that Chip is LP/Lp PATN1/PATN1. Exactly what I would want him to be. Lets think about this. First the LP/Lp or N/LP (Heterozygous for LP). LP is leopard complex spotting. Leopard complex or appaloosa spotting is a white pattern in horses characterized by a variable amounts of white in the coat with or without pigmented leopard spots. Horses with N/LP (Chip's genotype) will have a variable white pattern with pigmented spots. The size of the white pattern depends on what patterning modifiers are also present. They may transmit a leopard complex spotting variant to 50% of their offspring. Now it is my understanding that there are some modifiers to this percentage but this is still being researched. Matings with N/N genotype will result in a 50% chance of producing a foal with leopard complex/appaloosa spotting.
Further, expression of Leopard Complex is variable and white patterning may not be present in all horses that inherit the LP allele, but those with LP will progressively lose pigment as they age. Thus explaining how some appaloosas change in appearance. In addition to a white pattern, the expression of leopard complex includes several components: mottled skin around the muzzle, anus, genitalia, and eyes, stripped hooves, easily visible sclera (white of the eye) and progressive roaning, or loss of pigment, in the pigmented areas of the coat with age. The range of the white pattern can vary from minimal at birth to a horse that is almost completely white. The variability in the pattern is due to the interplay of multiple genes. Pigmented spots, known as leopard spots, can occur in white pattern areas.
LP is inherited as an incompletely dominant trait meaning the phenotype is different in horses with one or two copies of the LP variant. Horses with two copies LP/LP will have little to no leopard spots while those with one copy (N/LP) have pigmented spots in their white patterned area. The amount of white however is not dosage related, such that homozygous horses can have minimal expression of white patterning in the same manner that heterozygotes do. The variability in the amount of white on leopard complex patterned horses is controlled by other genes, one of which is PATN1.
THAT...now leads us to PATN1. Chip is PATN/PATN meaning he is homozygous for Pattern 1. Remember, Appaloosa Pattern-1 is a modifier of the leopard complex spotting (LP) and controls the amount white in the coat, increasing the amount of white present in horses that also have the LP mutation.
Horses Like Chip, with PATN1/PATN1 genotype that also have at least one copy of LP (N/LP or LP/LP) like he does, will have high amounts of white patterning. They will transmit an Appaloosa Pattern-1 variant to ALL of their offspring. The amount of white pattering on horses with LP and PATN1 typically range from 60-100%. This means that horses that are heterozygous for LP (N/LP), presence of the PATN1 mutation often produces a leopard or a near–leopard pattern. The effects of PATN 1, in the absence of LP are unknown. Maybe invisible, although some claim to observe white "ticking" of hairs on hips, belly and shoulder.
For more complete information please go to the UC Davis site. It's truly fascinating and new information is constantly evolving.

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