F R A M E
Frame is a gene on Chromosome 17 known for causing Overo Lethal White Syndrome when homozygous. By itself, frame doesn't tend to put very much white on a horse. Paired with another white pattern, whether it has been isolated and testable or not, it can create much more flashy markings. Frame is named as it is because of the way the pattern expresses, usually on the side of the neck or body "framed" by the color of the animal. Frame sometimes tends to favor top-heavy facial markings.
Because frame is lethal when homozygous, it is important for breeders to test for this gene before breeding two horses. Frame can express very minimally (including a completely solid horse with no white). As long as at least one horse of a breeding pair is negative, then the pairing will be safe. It is not worth the risk. OLWS is the result of the digestive tract of the foal not forming completely in utero. The intestinal tract is incomplete, with the nerves not being able to function and move food through the body. Thus the foal experiences painful colic symptoms and will die within 72 hours, if not euthanized first.
Because frame is lethal when homozygous, it is important for breeders to test for this gene before breeding two horses. Frame can express very minimally (including a completely solid horse with no white). As long as at least one horse of a breeding pair is negative, then the pairing will be safe. It is not worth the risk. OLWS is the result of the digestive tract of the foal not forming completely in utero. The intestinal tract is incomplete, with the nerves not being able to function and move food through the body. Thus the foal experiences painful colic symptoms and will die within 72 hours, if not euthanized first.
OO (lethal) or Oo