title: Congenital stationary night blindness is associated with the leopard complex in the Miniature Horse.
abstract: OBJECTIVE
  To determine if congenital stationary night blindness (CSNB) exists in the Miniature Horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the Miniature Horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas.
  
  
  METHODS
  Three groups of Miniature Horses were studied based on coat patterns suggestive of LP/LP (n=3), LP/lp (n=4), and lp/lp genotype (n=4).
  
  
  METHODS
  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature Horses.
  
  
  RESULTS
  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ(2) = 22, P << 0.0005) and CSNB status (χ(2) =11, P<0.0005).
  
  
  CONCLUSIONS
  The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.
authors: Department of Small Animal Clinical Sciences, University of Saskatchewan, Quill Lake, Saskatchewan, Canada. lynne.sandmeyer@usask.ca
authors: Lynne S
authors: LS
authors: Sandmeyer
authors: Rebecca R
authors: RR
authors: Bellone
authors: Sheila
authors: S
authors: Archer
authors: Bianca S
authors: BS
authors: Bauer
authors: Janelle
authors: J
authors: Nelson
authors: George
authors: G
authors: Forsyth
authors: Bruce H
authors: BH
authors: Grahn
mesh_terms: D000818:Animals; D004596:Electroretinography / Q000662:veterinary; D015785:Eye Diseases, Hereditary; D005260:Female; D040181:Genetic Diseases, X-Linked; D005838:Genotype; D006200:Hair Color / Q000235:genetics*; D006734:Horse Diseases / Q000235:genetics*; D006736:Horses; D008297:Male; D009216:Myopia / Q000235:genetics / Q000662:veterinary*; D009755:Night Blindness / Q000235:genetics / Q000662:veterinary*; D020641:Polymorphism, Single Nucleotide; D012880:Skin Pigmentation / Q000235:genetics*