The Creme Horse
The White Horse
and the Lethal White Syndrome (Albinos)

 

Here is the reply once and for all
from worldwide renowned geneticiens

 

The Creme Horse

The cream gène (Ccr) is a diluting gene that dilutes the colour of a horses coat and has absolutely nothing to do with the albino gene. (LWO) Lethal White Overo.

The Creme Gene Ccr.
A chestnut / Sorrel horse with one creme gene Ccr will be palomino, a bay horse with one creme gene Ccr will be buckskin and a black horse with one creme gene Ccr will be smokey black. When two creme genes are present (Ccr Ccr) the coat will be diluted again and the palomino will become a Cremello, the buckskin a Perlino and the Smokey Black will become a Smokey Creme. The horse will always have pigmentation in the skin, the hair and the eyes, nomatter how small. The only really pink skin and white hair will be the marks on the head (blaze etc) and the socks if the horse has any.     (gene table)

 
THE CREME HORSE

The White Horse

     The white gene (W) is the gene responsable for the white horse with the pink skin and almost always dark eyes, exemple The American White Horse. A normal coloured horse will be (w w) non white and a white horse will be (W w).

When one crosses two horses (ww) the result will be (ww) a normal coloured horse.

When one crosses two horses, one (ww) and the other (Ww) the result will be
either (ww) a normal coloured horse.
or (Ww) heterozygotes a white horse.

When one crosses two horses, one (Ww) and the other  (Ww) the result will be
either (ww) a normal coloured horse.
or (Ww) heterozygote a white horse.
or (WW) homozygote that dies in utero.

THE WHITE HORSE

 

The Lethal White Overo Syndrome
The Lethal White Overo gene (LWO)

Lethal White Overo Syndrome or Congenital Intestinal Aganglionosis.   

     To not confuse with the white horse we will use the letter (O) for the lethal white overo gene and the letter (N) for the non lethal white gene. The gene (O) Lethal White Overo gene is the gene responsable for the birth of completely depigmented foals they have a completely white coat and blue eyes. These geneare typically from the frame overo (white marks on the coat with darker frilly oulines). This is caused by the dominent action of the gene Frame ( Fr ). The (O) gene, does not have any prejudices and attacks horses of no matter what colour even solid horses that are not classed as "Overos". To better understand this gene one must remember that a foal recieves two genes, one from each of its parents.

We will use the letter (O) for the lethal white overo gene
the letter (N) for the non lethal white,

foals that are (NN) are foals that do not have the overo gene.
foals that are (NO) are foals that do have the overo gene
and foals that are (OO) are the lethal white overo foals.

    When two (NO) horses are crossed together one of the following happens.
1°     (NO) + (NO) = (NN) foals that do not have or carry the overo gene.
2°     (NO) + (NO) = (NO) foals that do have the overo gene
3°     (NO) + (NO) = (OO) the lethal white overo foal.

Warning :   A solid coloured horse with overo in the breeding can be a carrier of the lethal white overo gene.

When one crosses two (NN) horses, the result is
(NN) therefore does not have the lethal white gene.

When one crosses two horses , one (NN) and the other (NO) the result is
either (NN) does not have  the lethal white gene.
or (NO) does have  the lethal white gene.

When one crosses two horses , one (NO) and the other (NO) the result is
either (NN) does not have  the lethal white gene.
or (NO) does have  the lethal white gene.
or (OO) homozygote that produces le the lethal white overo syndrome (OO), the foal has absolutely no pigmentation and is not viable. The vital role that pigmentation plays in the body especially the intestins is faulty. When this internal pigmention is faulty, there cannot be intestinal peristaltisme whichmeans that all digestion is impossible. The foal gives off signs of colic and dies within 24 hours of birth. A surgical intervention has never been sucessful and euthanasia is the only humaine ending.

 Now that a DNA test for the (LWO) gene existes, the Overo horses can be tested for this gene. Two horses who carry this gene should not be crossed together, which means that no lethel white overo foals should ever be born.

 This is why we find only albino heterozygotes (NO), in which the lethal white gene (O) leaves the internal organs and eyes pigmented.

LETHAL WHITE OVERO FOAL (albinos)
this foal will die within the day