Natural gene / phase 1

Pangaré — the pale underside

Also called mealy. The pale muzzle, eye rings, belly, flanks and inner legs of an Exmoor pony, a Fjord or a Haflinger: the soft parts of the horse go cream and the topline does not.

Crossing two of them

This gene has no effect on the horse’s health.

Breeds

Five breeds name the locus, at rates that follow the study’s marker frequencies rather than being invented: Exmoor Pony and Norwegian Fjord near-fixed, Icelandic Horse common, Shetland Pony and Suffolk Punch moderate. Every other breed is pa/pa, because a breed that does not name a coat locus gets it wild; the feral population carries the full spread.

Its gene carrot

Gene key
horsegenetics.pangare
Alleles
Pa2 Pa1 pa
Outcomes
wild, trace-pangare, mild-pangare, pangare, strong-pangare
Default allele
pa
Priority
PangareGene.PRIORITY — immediately after sooty, its mirror
Founder draws
1 × nextFloat()
Deterministic
no when expressed
Epi draws
1 × nextFloat — the expression roll
Health
none established
Unplayed

Covered by PangareGeneTest and the golden file, and eyeballed as side views. Not seen in a game. See verification §0-U.

The exact mirror of sooty

Sooty keeps black along the topline; pangaré takes red away from the underside. Both are one region-weighted move on one pigment, they sit next to each other in the order, and between them they are the two halves of countershading. A horse carrying both is the textbook version: dark back, pale belly.

Working on red is why there is no per-colour table

The reference gives a long list of rules for how pangaré should render on each base. Every one of them falls out of removing red rather than removing lightness, and none of them is a special case in the gene:

  • Chestnut — maximum visibility. Nothing masks the red, so taking it walks the sample toward cream and pale gold.
  • Bay — the red-brown body lightens and the black points do not. A point is stored as red 0 and black 1: there is no red on it to take.
  • Black — nothing visible at all. A black horse’s red is entirely masked by its black, and the gradient’s bottom row is one colour whatever the red says. The reference calls pangaré hard to recognise on black; here it is invisible, exactly.
  • Double dilute — visually redundant, because the coat is already nearly out of red.

The dosage

CombinationDosageOutcomeWhat shows
pa/pa0wild typenothing
Pa1/pa1trace-pangarea pale lower muzzle and faint eye rings
Pa1/Pa1, Pa2/pa2mild-pangarepale muzzle and eye rings, a light underline, soft patches behind the elbows
Pa2/Pa13pangarethe familiar mealy horse — pale jaw, belly, groin, flank and inner legs
Pa2/Pa24strong-pangarebroad cream soft areas climbing the barrel; outer legs and black points still dark

A pale muzzle alone does not identify the trait — ordinary shade variation looks the same, which is what trace-pangare is for.

Where it sits

The weights are the reference’s own region table; what the gene adds is the shapes they hang on. Muzzle 1.00, eye rings 0.90, belly 0.92, groin 0.82, behind the elbow 0.74, jaw 0.72, flank 0.70, inner leg 0.70, lower neck 0.30, outer leg 0.12, and nothing at all on the mane, tail, ears or dorsal line — a horse with a pale mane has flaxen, silver or cream instead.

The inside of a leg — a helper that did not exist

Closes known gap #51

Every other region helper in CoatRegions addresses a part. “The inside of a leg” is a face of a part, which is a different question, and it is why this went undrawn: a leg is a box, its four sides are all at the same distance from its own axis, and nothing about a body point distinguishes the inner side from the outer. The information was in the Face the visitor is already handed, and was simply going unused.

CoatRegions.medial is that, and the reason it is a shared helper rather than eight lines in this file is the per-leg mirror: a leg on the horse’s right faces inward on its left side and a leg on the left faces inward on its right. Written out per gene, that is exactly the kind of thing one of the four legs quietly gets backwards.

It has two users, which is what the gap asked for before it was built: this, and the seal brown’s soft points, whose fifth and last one is the pale inner limb.

Health

None — and there is a specific trap here

There is no established pangaré-associated disease, defect or welfare problem, and the mod gives it no TraitContribution.

The trap is that the EDN3 region has been tied, in later work, to exercise blood pressure and harness-racing performance in coldblooded trotters. That is a regulatory haplotype under study in a racing population, not a pangaré test: a mealy Fjord is not hypertensive and is not athletically limited.

And it is not frame overo, whose lethal white foal syndrome comes from EDNRB — a different gene with a confusingly similar name.

What is actually known

No confirmed causal mutation and no test. Breeders have treated pangaré as heritable for as long as anyone has kept records — it is near-fixed in several breeds — but its inheritance mode is unresolved, and the very wide range of intensity points at several loci rather than one.

The nearest thing to evidence is a 2018 population study of a region on chromosome 22 about 50 kb downstream of EDN3, whose allele frequencies split sharply between athletic breeds and the pony and draft breeds where mealy is pervasive:

Marker atBreeds
99–98%Fjord, Haflinger, Exmoor
90–74%North Swedish Draught, Gotlandsruss, Ardennes, Icelandic
58%Shetland
8–1%Quarter Horse, Swedish Warmblood, Shire, Thoroughbred

That is an association between a marker and a breed group, not a cause, and the authors said so. So the locus here is a dosage with a per-horse roll — the same shape as flaxen, sooty and the bay shade score — and the population evidence lands where it actually belongs, in the breed frequencies.

Source: common/genetics/genes/PangareGene.java, common/coat/pattern/CoatRegions.medial