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  • Author or Editor: M. Cecilia T. Penedo x
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Objective—To determine the mode of inheritance for cerebellar abiotrophy (CA), a neurologic disease in Arabians.

Animals—804 Arabians, including 29 horses (15 males and 14 females) with CA.

Procedures—Most horses (n = 755) belonged to 1 of 4 paternal families. Among the 29 CA-affected horses, all had clinical signs consistent with the disease; the disease was confirmed histologically following euthanasia in 8 horses. From the pedigree information, inbreeding coefficients were calculated for 16 affected horses and compared with coefficients for a subgroup of 16 unaffected horses. Complex segregation analysis was used to determine the effect of a putative Mendelian locus on the development of the disease and the probable mode of inheritance of CA.

Results—The mean inbreeding coefficient was 0.0871 for CA-affected and unaffected horses, suggesting that all of the Arabians were inbred to the same degree and that affected horses were not more inbred than were unaffected horses. Results of the complex segregation analysis were consistent with a single Mendelian autosomal recessive mode of inheritance.

Conclusions and Clinical Relevance—Knowledge of the mode of inheritance of CA should help breeders to make informed decisions regarding the selection of animals for mating when closely related horses have developed CA or produced CA-affected foals.

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in American Journal of Veterinary Research


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).

Design—Prospective genetic survey.

Animals—651 elite performance AQHs, 200 control AQHs, and 180 control American Paint Horses (APHs).

Procedures—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 and Clinical Relevance—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.

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in Journal of the American Veterinary Medical Association