Color: Overo white color pattern
Samples Accepted: Blood, Hair
Locus Information: O series
The mutation causing the overo white color pattern is also responsible for intestinal development; homozygous foals die soon after birth (Over lethal white syndrome, OLWS).
Test Information: This test is based on a mutation in the EDNRB gene. The overo color pattern is autosomal dominant, as any animal with one copy of the allele will have the pattern. A foal with two copies of the gene will be all or nearly all white, have an incompletely developed intestine and die of the autosomal recessive disease known as Overo Lethal White Syndrome (OLWS).
Metallinos, DL; Bowling AT; Rine J (June 1998). “A missense mutation in the endothelin-B receptor gene is associated with Lethal White Foal Syndrome: an equine version of Hirschsprung Disease”. Mammalian Genome 9 (6): 426–31 Abstract
Further information is available at the Online Mendelian Inheritance in Animals website.