Evaluation of allele frequencies of inherited disease genes in subgroups of American Quarter Horses.
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.
Tryon
Robert C
RC
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Penedo
M Cecilia T
MC
McCue
Molly E
ME
Valberg
Stephanie J
SJ
Mickelson
James R
JR
Famula
Thomas R
TR
Wagner
Michelle L
ML
Jackson
Mark
M
Hamilton
Michael J
MJ
Nooteboom
Sabine
S
Bannasch
Danika L
DL
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
D015061:1,4-alpha-Glucan Branching Enzyme