Chronic progressive lymphoedema in Friesian horses: suggestive phenotype of affected horses and genome-wide association study.

Abstract

Chronic progressive lymphoedema (CPL) is a disabling condition affecting various draft horse breeds, including Friesian horses. The high incidence of CPL in Friesian horses suggests a genetic component and a predisposing phenotype. For the genomic study, 26 affected and 19 control horses were evaluated. Body measurements were taken from 28 affected and nine control Friesian horses. Axiom® Equine Genotyping Array with a total of 307,474 single nucleotide polymorphism (SNPs) was used for the case/control genome-wide association study (GWAS). Height, weight and leg measurements (seven different body measurements) were obtained and compared between groups. No significant associations were identified with the GWAS. There were significant differences (P<0.05) in gaskin length measurements between CPL-affected horses and controls. The current study suggests that the potential genetic contribution to CPL in Friesian horses is complex and may include other SNP-associated factors. Significantly increased gaskin length of affected horses suggests a phenotype prone to developing CPL.