Topic
Overo
About: Overo is a research topic. Over the lifetime, 19 publications have been published within this topic receiving 531 citations.
Papers
TL;DR: Molecular definition of the basis for OLWS in Paint Horses provides a genetic test for the presence of the Lys 118 EDNRB allele and adds to the understanding ofThe basis for coat color patterns in the horse.
Abstract: Overo lethal white syndrome (OLWS) is an inherited syndrome of foals born to American Paint Horse parents of the overo coat-pattern lineage. Affected foals are totally or almost totally white and die within days from complications due to intestinal aganglionosis. Related conditions occur in humans and rodents in which mutations in the endothelin receptor B (EDNRB) gene are responsible. EDNRB is known to be involved in the developmental regulation of neural crest cells that become enteric ganglia and melanocytes. In this report we identify a polymorphism in the equine EDNRB gene closely associated with OLWS. This Ile to Lys substitution at codon 118 is located within the first transmembrane domain of this seven-transmembrane domain Gprotein-coupled receptor protein. All 22 OLWS-affected foals examined were homozygous for the Lys118 EDNRB allele, while all available parents of affected foals were heterozygous. All but one of the parents also had an overo white body-spot phenotype. Solidcolored control horses of other breeds were homozygous for the Ile 118 EDNRB allele. Molecular definition of the basis for OLWS in Paint Horses provides a genetic test for the presence of the Lys 118 EDNRB allele and adds to our understanding of the basis for coat color patterns in the horse.
159 citations
Abstract: The lethal white foal syndrome (LWFS) is a congenital abnormality of overo spotted horses which is a model for human aganglionic megacolon or Hirschsprung disease. Foals with LWFS have an all white, or nearly all white, coat. They also present clinically with an intestinal obstruction that proves fatal within the first few days of life. The LWFS involves both melanocytes and intestinal ganglion cells, and appears to result from a genetic defect involving neural crest cells. This report describes pathologic studies of two recent cases of LWFS. Two different hypothetical models of inheritance of LWFS are presented and discussed.
76 citations
Journal Article•
TL;DR: The congenital absence of myenteric ganglia in the terminal portion of the ileum, cecum, and entire colon of white foals with overo spotted parents was reported.
Abstract: The congenital absence of myenteric ganglia in the terminal portion of the ileum, cecum, and entire colon of white foals with overo spotted parents was reported. Males as well as females were affected. The foals were generally normal at birth but did not defecate. Signs of colic were noticed between 5 and 24 hours after birth, with death occurring at 23 to 132 hours.
60 citations
TL;DR: Veterinarians should be aware of deafness among American Paint Horses, particularly those with a splashed white or frame overo coat color pattern, blend of these patterns, or tovero pattern, as horses with extensive head and limb markings and those with blue eyes appeared to be at particular risk.
Abstract: Objective—To evaluate deafness in American Paint Horses by phenotype, clinical findings, brainstem auditory-evoked responses (BAERs), and endothelin B receptor (EDNBR) genotype. Design—Case series and case-control studies. Animals—14 deaf American Paint Horses, 20 suspected-deaf American Paint Horses, and 13 nondeaf American Paint Horses and Pintos. Procedures—Horses were categorized on the basis of coat color pattern and eye color. Testing for the EDNBR gene mutation (associated with overo lethal white foal syndrome) and BAERs was performed. Additional clinical findings were obtained from medical records. Results—All 14 deaf horses had loss of all BAER waveforms consistent with complete deafness. Most horses had the splashed white or splashed white–frame blend coat pattern. Other patterns included frame overo and tovero. All of the deaf horses had extensive head and limb white markings, although the amount of white on the neck and trunk varied widely. All horses had at least 1 partially heterochromic iri...
44 citations
Journal Article•
TL;DR: Assessment of hearing should be considered, especially in paint horses, at the time of pre-purchase examination, because brainstem auditory evoked potential assessment is well tolerated and accurate.
Abstract: Deafness was confirmed in a blue-eyed, 3-year-old, overo paint horse by brainstem auditory evoked potential. Congenital inherited deafness associated with lack of facial pigmentation was suspected. Assessment of hearing should be considered, especially in paint horses, at the time of pre-purchase examination. Brainstem auditory evoked potential assessment is well tolerated and accurate.
24 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2017 | 1 |
| 2016 | 1 |
| 2015 | 1 |
| 2012 | 1 |
| 2009 | 1 |