What is the Cream Gene?
Cream is an incomplete dominant gene in the dilution
category. (Remember, incomplete
dominant means there is a different visible effect depending on whether the
horse has once copy of the gene or two copies of the gene, and dilution type
genes are those that cause the color to be lightened in some way.)
The symbol for this gene is "Cr".
The gene was isolated in 2001, and a test for it has been available since
2003.
Cream is the most common of the dilution genes, giving the
popular palomino and buckskin colors (among others). It has been known for many years, but was poorly understood
in the early days. Even to this
day, there is confusion about the inheritance of these colors, due to the nature
of an incomplete dominant gene, and due to the fact that Cream, like Silver, is
pigment-specific. Just as Silver
only dilutes black pigment and not red, Cream only dilutes red pigment and not
black when heterozygous. This can
cause the gene to "hide" on a black or seal brown horse, and therefore
appear to skip one or more generations, even
though, like any dominant gene, at least one parent must have the gene in order
for the foal to have it.
The vast amount of misidentification, misunderstanding, and
mistaken ideas about cream-dilutes that has occurred over the years would be
enough to fill an entire website, so let's just say that thankfully, the gene is
well understood today, and leave it at that.
How does the Cream gene work?
When a horse has one
copy of the Cream gene (is heterozygous), it acts on any red hair by lightening
it to golden yellow. Manes and
tails are lightened even further, usually to white.
The skin and eye color are not changed (although it's not uncommon for
them to be born with pinkish skin and blue eyes, which darken to the normal
adult color over a few days or weeks). Black
hair is generally unchanged, although it often has a tendency to sunbleach much
more readily, and some horses do seem to have more of a dark chocolate-brown
tone than jet black. Any dark
"sooty" hairs that may be present will remain undiluted, and this can
be extreme.
Palomino
A chestnut with one
Cream gene is called a palomino. The
typical palomino is golden yellow with a white mane and tail.
But like any other color, they range in shade from very light to very
dark. A palomino can be so light as
to appear near-white, or so dark as to appear near-black.
The more extreme variations are rare, thank goodness!
These can be difficult to identfy without genetic testing.
The more common color range of light yellow to dark gold, almost coppery,
is believed to be caused by the underlying base color, that is, whether the
horse would have been a light chestnut, medium red chestnut,
or dark liver chestnut if it didn't have a Cream gene.
This theory is logical, but unproven yet because it is unknown what
genetic mechanism causes variations in shade.
The really dark palominos are "sooty" and have near-black hairs
mixed into their body, mane and tail to varying degrees, even to the point of
appearing nearly black all over.
Buckskin
A bay with one Cream
gene is called a buckskin. The
typical buckskin is golden bodied with black points.
Like palominos, they can range in shade from very light (often called
"buttermilk buckskin") to very dark (often called "bronze
buckskin"). A buckskin that is
"sooty" will have black hairs mixed in the coat, from a little to a
lot. A very sooty buckskin can be
so dark that it may not look dilute at all.
Sooty buckskins are often strongly dappled.
Smoky Black
A black with one Cream gene is called a smoky black.
Often they don't look any different from a regular black, but some look
almost like a liver chestnut, seal brown, or grulla.
It's not uncommon for them to bleach out in the summer to a buckskin or
grulla-like shade. At birth they
often, but not always, have pinkish skin, blue eyes, and golden hair inside the
ears; these can be good clues that a foal is smoky black, but only testing can
say for sure. Most registries do
not recognize the color, so they are typically registered as black, brown, or
grulla.
Seal Brown with one Cream gene
A seal brown with one Cream gene does not have an
"official", universally recognized name at this time, but they are
most commonly called "brown buckskin" or "brown with cream",
or, in some places, "black buckskin".
They may look like a dark, sooty buckskin, or they may look like a seal
brown with little or no clue that the dilution is present.
Often only genetic testing can tell them for certain apart from a dark
buckskin or a seal brown. Registries
(and most breeders) don't have a separate category for them, so they are usually
registered as brown, or as buckskin if light enough.
Double Cream Dilutes
When a horse has two copies of the Cream gene (is
homozygous), the effect is what is commonly called "double-diluted".
Both red and black hair is diluted to a cream color, with the black hair
often (but not always) having a slightly reddish or peachy tint. The skin is pink, and the eyes are light blue.
If the horse has any white markings, they may or may not be visible.
Some are so light they just "look white" all over. The pink skin under white markings ought to be a bit lighter
-- technically speaking, the skin of a double-dilute does have some pigment, it
is just diluted; while the skin under white markings has no pigment at all.
For this reason the pink skin of a double-dilute does not tend to sunburn
as readily as the pink skin under white markings.
In practice, though, it can be very difficult to see any difference.
The skin of double-dilutes does tend to develop some freckling over time,
especially where exposed to the sun, but this is not to be confused with the
freckling on a champagne; it looks quite different, not the darker, more
distinct dots that champagne skin has, but a more subtle freckling like we might
get on our skin.
A chestnut with two Cream genes is called a cremello.
Typically they are a light cream color with white mane and tail.
Usually they just look "white", especially from a distance. Some are dark enough to make out any white markings, some
aren't. They sometimes get dapples,
a subtle and beautful effect on this color.
A bay with two Cream genes is called a perlino.
Typically they are cream-colored on the body, with slightly darker,
reddish-tinted points. Some are so light they look cremello, and some are darker,
almost a pale peachy color.
A black with two Cream genes is called a smoky cream.
Theoretically, they should be a bit darker in shade, but in real life
these have been found in a variety of shades from light like a cremello, to a
darker peachy cream, to almost a light greyish tone.
Genetic testing is usually needed to pinpoint exactly what color they
are. Registries typically don't
recognize smoky creams and would call them perlino, if that color is recognized,
or whatever else they felt was closest.
A seal brown with two Cream genes does not have any specific
name yet, and would most likely look like and be called a perlino.
Genetic testing would be needed to tell them apart.
Breeds with the Cream Gene
The Cream gene is the most common and widespread of the
dilution genes and it is present in many breeds. It's widespread in all of the "Western" type
American breeds such as QH, Paint, Appaloosa, and Mustang. It's fairly common in most of the American gaited breeds such
as the ASB, TWH, MFT, and Racking Horse; and is present but not as common in
Rocky Mountain and Mountain Pleasure horses.
It's present but not common in the "Spanish" breeds such as the
Pasos, Andalusian, and Lusitano. It's
present, but fairly rare, in the Morgan and Thoroughbred. It is present in a few
Warmblood breeds like the Dutch, Danish, and Swedish WBs and possibly the
Trakehner and Selle Francais. It is
not present in the modern Standardbred or Hackney, or the Arabian.
The only draft breed that is known to have the gene is the American Cream
Draft (most of which are champagnes, but some are champagne creams).
It occurs in several pony breeds such as Welsh, Shetland, Connemara,
Icelandic, and Mini. Fjords are all
dun, but some are cream as well. Haflingers,
although often called "palomino", do not have the gene; they are all
chestnut (some very light flaxen chestnut, but not palomino).
For photo examples, please see the
links on the left.
