title: Evaluation of allele frequencies of inherited disease genes in subgroups of American Quarter Horses.
abstract: OBJECTIVE
  To estimate allele frequencies of the hyperkalaemic periodic paralysis (HYPP), lethal white foal syndrome (LWFS), glycogen branching enzyme deficiency (GBED), hereditary equine regional dermal asthenia (HERDA), and type 1 polysaccharide storage myopathy (PSSM) genes in elite performance subgroups of American Quarter Horses (AQHs).
  
  
  METHODS
  Prospective genetic survey.
  
  
  METHODS
  651 elite performance AQHs, 200 control AQHs, and 180 control American Paint Horses (APHs).
  
  
  METHODS
  Elite performance AQHs successful in 7 competitive disciplines (barrel racing, cutting, halter, racing, reining, western pleasure, and working cow horse) were geno- typed for 5 disease-causing alleles. Age-matched control AQHs and APHs were used to establish comparative whole-breed estimates of allele frequencies.
  
  
  RESULTS
  Highest allele frequencies among control AQHs were for type 1 PSSM (0.055) and GBED (0.054), whereas HERDA (0.021) and HYPP (0.008) were less prevalent. Control APHs uniquely harbored LWFS (0.107) and had high prevalence of HYPP (0.025), relative to AQHs. Halter horse subgroups had significantly greater allele frequencies for HYPP (0.299) and PSSM (0.155). Glycogen branching enzyme deficiency, HERDA, and PSSM were found broadly throughout subgroups; cutting subgroups were distinct for HERDA (0.142), and western pleasure subgroups were distinct for GBED (0.132). Racing and barrel racing subgroups had the lowest frequencies of the 5 disease genes.
  
  
  CONCLUSIONS
  Accurate estimates of disease-causing alleles in AQHs and APHs may guide use of diagnostic genetic testing, aid management of genetic diseases, and help minimize production of affected foals.
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Tryon
authors.forename: M Cecilia T
authors.initials: MC
authors.lastname: Penedo
authors.forename: Molly E
authors.initials: ME
authors.lastname: McCue
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Valberg
authors.forename: James R
authors.initials: JR
authors.lastname: Mickelson
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Famula
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Wagner
authors.forename: Mark
authors.initials: M
authors.lastname: Jackson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hamilton
authors.forename: Sabine
authors.initials: S
authors.lastname: Nooteboom
authors.forename: Danika L
authors.initials: DL
authors.lastname: Bannasch
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000172:deficiency / Q000235:genetics; D000818:Animals; D001247:Asthenia / Q000235:genetics / Q000662:veterinary; D005260:Female; D005313:Fetal Death / Q000235:genetics / Q000662:veterinary; D005787:Gene Frequency; D005804:Genes, Lethal; D030342:Genetic Diseases, Inborn / Q000235:genetics / Q000662:veterinary*; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006011:Glycogen Storage Disease Type IV / Q000235:genetics / Q000662:veterinary; D006200:Hair Color / Q000235:genetics; D006734:Horse Diseases / Q000235:genetics*; D006736:Horses; D008297:Male; D020513:Paralysis, Hyperkalemic Periodic / Q000235:genetics / Q000662:veterinary; D010375:Pedigree; D011247:Pregnancy; D011446:Prospective Studies; D013577:Syndrome
chemical_list: D015061:1,4-alpha-Glucan Branching Enzyme