• About This Guide
  
• How This Guide is Being Developed
  
• Philosophy of this guide
  
• Using this Guide
  
• Thinking Scientifically
  
• About the Author
  
• Documented Genes
  
• What is a documented gene?
  
• Black/Red (MC1R)
  
• Bay (ASIP)
  
• Cream/Pearl (SLC45A2)
  
• Dun (TBX3)
  
• Gray (STX17)
  
• Silver (PMEL17)
  
• Champagne (SLC36A1)
  
• Roan/Tobiano/Sabino/White Spotting (KIT)
  
• Splash White (MITF/PAX3)
  
• Leopard Complex (TRPM1/ECA3P)
  
• Frame (EDNRB)
  
• Tiger Eye (SLC24A5)
  
• Height Regulation (HMGA2/LCORL)
  
• Mushroom (MFSD12)
  
• Hypothetical Genes
  
• What is a hypothetical gene?
  
• Borrowed Genes
  
• Glossaries
  
• Glossary of Colors
  
• Glossary of Terms
  

Frame (EDNRB)

• Last updated: 2026-01-19

  Common Names: Frame, Overo, Lethal White Overo

  Scientific Name: Endothelin Receptor Type B (EDNRB)

  Equine Chromosome: 17

  General Overview:

  The frame gene is named for the frame of color it tends to leave around a white torso. It readily combines with other pinto markings like splash and tobiano to produce particularly bold markings. Frame is incompletely dominant requiring only one copy to show. When homozygous it produces all or nearly all white foals who do not live more than a few days. [1]

• Citations:
  Santschi EM, Purdy AK, Valberg SJ, Vrotsos PD, Kaese H, Mickelson JR. Endothelin receptor B polymorphism associated with lethal white foal syndrome in horses. Mamm Genome. 1998 Apr;9(4):306-9. doi: 10.1007/s003359900754. PMID: 9530628.  https://pubmed.ncbi.nlm.nih.gov/9530628/

• Examples:

  A range of frame expressions