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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