Lethal white syndrome

The Overo Lethal White gene is a gene that is involved in the inheritance of coat color in horses. It is inherited incompletely dominant and caused by mutation of the endothelin receptor B locus leucism. A horse that this gene is only once usually shows a frame overo spotting and healthy. If the Lethal White gene inherited from both parents ( homozygous is so ago), it leads to OLWS ( Overo Lethal White Syndrome ).

Breeds and colors can occur in which the gene

Well over 90 % of the frame Overos, Highly -White Calico Overos and frame blend Overos carry the gene.

Has a horse in addition, the tobiano gene, it usually shows a Tobiano and no overo spotting.

Also in various other Scheckungsmustern and even in solid colored animals may exceptionally be a frame overo gene, without the spotting expresses clearly identifiable. In the samples Sabino, Minimally -White Calico Overo, Splashed White Overo, Nonframe blend overo and ungescheckten horses of the races in which the Overoscheckung occurs, the proportion of gene carriers is below 20 %. In races without Scheckungsmuster the gene does not occur.

Therefore, it is advisable to test all horses of breeds that contain frame - Overos on this gene to be sure that you can not, without knowing it, crosses two carriers of this gene.

Lethal White Foal Syndrome

If the Lethal White gene inherited from both parents ( homozygous is so ago), it leads to OLWS ( Overo Lethal White Syndrome ). Such foals are completely white. Since the neurons are not correctly migrated from the neural tube, the gastrointestinal tract is not sufficiently supplied with nerve cells. You are missing at the end of the small intestine ( Ileumendstück ) in the cecum and the entire colon. Leading to intestinal obstruction, and therefore the large intestine expands (megacolon ), and finally performs a colic death of the foal. The Lethal White Foal Syndrome - corresponding to the Hirschsprung 's disease in humans. Within the first days of life the foal die. 2

Frame Overo

The term frame overo (Fr and fr) of "frame" that is to say in English "frame", comes from the fact that the proportion of white spotting is on the side of the horse's body and neck and works through the dark places such as framed. No white spot crosses the back line, only at the neck cross the white spots sometimes the mane comb. At least one leg, but often all four are dark. The face often has very distinctive badge like a lantern. The spots are usually irregular borders, such as frayed.

Other Overo piebald

In addition to the frame overo gene, there are other genes that can cause an overo spotting. For example, the well - Splashed White is assigned to the form of the circle Overoscheckung, although he has a different genetic cause. Likewise Sabinoschecken were assigned to the overo form a circle. Conversely, not every horse with the frame overo gene a frame overo spotting.