Idiopathic Epilepsy Risk Allele Trends in Belgian Tervuren: A Longitudinal Genetic Analysis

Abstract

Idiopathic epilepsy (IE) has been known to be inherited in the Belgian Tervuren for many decades. Risk genotypes for IE in this breed have recently been identified on Canis familiaris chromosomes (CFA) 14 and 37. In the current study, the allele frequencies of these loci were analyzed to determine whether dog breeders had employed a purposeful selection against IE, leading to a reduction in risk-associated allele frequency within the breed over time. The allele frequencies of two generational groupings of Belgian Tervuren with and without IE were compared. Allele frequencies for risk-associated alleles on CFA14 were unchanged between 1985 and 2015, whereas those on CFA37 increased during that time in the control population (p < 0.05). In contrast, dogs with IE showed a decrease (p < 0.05) in the IE risk-associated allele frequency at the CFA37 locus. Seizure prevalence in the Belgian Tervuren appears to be increasing. These results suggest that, despite awareness that IE is inherited, selection against IE has not been successful.

Keywords: Belgian Tervuren; dog; idiopathic epilepsy; neurological disorder; seizure; selective breeding.

Figure 1

Changes in observed CFA14 and CFA37 interacting risk haplotype block frequency over time in 175 unrelated Belgian Tervuren (BT). Haplotypes are ordered by increasing risk, with the haplotype interactions on the far right being highly associated with IE in Belgian Tervuren [35].